Abstract:
An improved method for the manufacture of hot strips or heavy plates from a denitrated steel composed of 0.04 to 0.16% carbon, 1.25 to 1.90% manganese, 0.2 to 0.55% silicon, 0.004 to 0.020% phosphorus, 0.002 to 0.015% sulfur, 0.02 to 0.08% aluminum, 0.02 to 0.08% niobium, the remainder iron and possibly contaminants, including the steps of having the hot strips or plates leaving the last finishing stand of rolls at a temperature of 750° C. to 820° C., cooling the hot strips or plates to an intermediates temperature of 450° C. to 500° C. at a cooling rate of 2° to 10° C./s and then slowly cooling the hot strips or plates in air to room temperature in a coil or in a pile.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a method for the manufacture of hot strips or heavy plates from a denitrated steel. 
     For a long time the demand continued for the development of higher strength steels with high toughness values at low temperature, in the form of hot strips or heavy plates. These are used, for example, in large diameter long-distance pipelines. Controlled hot rolling has been used more and more as an economical method for the production of thermo-mechanically treated hot strips or heavy plates. As part of a thermo-mechanical treatment for steels it is understood to effect a controlled transformation of the steel in a temperature range around the transformation point A r .sbsb.3 with a simultaneously controlled cooling and/or transformation of the structure. 
     It is known to use denitrated steel with a composition of 0.04 to 0.16% carbon, 1.25 to 1.90% manganese, 0.02 to 0.55% silicon, 0.004 to 0.020% phosphorus, 0.002 to 0.015% sulfur, 0.02 to 0.08% aluminum, 0.2 to 0.08% niobium, the remainder being iron and possibly contaminants. The steel can also be alloyed with the addition of 0.015 to 0.35% molybdenum, 0.10 to 0.30% chromium and/or 0.30 to 0.90% nickel, alone or in combination. 
     During the mechanical-technological testing of these steels, particularly with the presence of notches and over a wide temperature range, one frequently observes splits perpendicular to the fracture surface in the upper part of the complete brittle failure stage. These are designated &#34;separations&#34;, &#34;cleavage&#34; or &#34;splitting&#34;. This tendency of splitting at the fracture surface of thermo-mechanically treated steel is, for example, of significance in the operation of large diameter long-distance pipelines, since the capacity of these steels to stop fracture propagation is thereby reduced. 
     Proposals have already been made for the production of higher strength steels for use in large diameter long-distance pipelines in which splitting at the fracture during the notch impact testing is no longer found. However, high alloying and manufacturing costs are connected with all of them. For example, it is recommended in De-OS No. 26 53 847 to alloy the steel by up to 3.5% or 2.5% addition of chromium and manganese, after the steel has been subjected to a nitrogen enrichment up to a content of 0.012%. Furthermore the hot rolling of this steel is complicated. The rolled stock will be subjected to a deformation from 30 to 60% at temperatures between 950° C. and 1100° C., a subsequent prescribed interruption of hot rolling and a deformation of 75 to 95% of the original thickness at temperatures between 700° C. and 900° C. The deformed structure will finally be converted into the lower bainite stage. The alloying of the chromium and manganese additions raises the price of the known steels considerably. On account of the complicated and expensive rolling operation further increased manufacturing costs arise. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to obtain an increased notch impact toughness for hot-rolled hot strips or heavy plates through a controlling of the occurrence of separations. 
     A further object of the present invention is to obtain such an increased notch impact toughness at low temperatures, that is to have a CVN-transition temperature TU 50  of at least -30° C. 
     These objects will be achieved according to the present invention by subjecting a steel of composition 0.04 to 0.16% carbon, 1.25 to 1.90% manganese, 0.02 to 0.55% silicon, 0.004 to 0.020% phosphorus, 0.002 to 0.015% sulfur, 0.02 to 0.08% aluminum, 0.02 to 0.08% niobium, the remainder iron and possibly contaminants, to a hot-rolling operation in which the hot strip or the plate leaves the last finishing stand of rolls with a temperature of 750° and 820° C., is cooled at a rate of 2° to 10° C. per second to an intermediate temperature of 450° C. to 570° C., and is at this temperature coiled or placed in a pile for further cooling. 
     Surprisingly, it turns out that only upon the observance of the described, relatively simple hot-rolling operations for the mentioned steel will there appear a significant reduction in splitting at the fracture during the CVN-notch impact test (CVN: Charpy-V-Notch) at CVN-transition temperatures as low as -30° C., and therewith a considerably increased notch impact toughness. 
     Following the method according to the invention the usefulness of the steel, for example in large diameter long-distance pipelines, can be considerably improved without the necessity of excessive alloying. 
     The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a photo of a fracture struck in a notch impact test. 
     FIG. 2 is a graph relating notch impact toughness values (ordinate) to the ratio Cvmax: Cv100 (abscissa). 
     FIG. 3 is analogous to FIG. 2, using steels of various composition. 
     FIGS. 4 and 6 are graphs relating notch impact toughness values to coiling temperature. 
     FIGS. 5 and 7 are graphs relating the ratio Cvmax:Cv100 to coiling temperature. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It turns out that a particularly favorable enhancement in the strength characteristics of steel produced according to the present invention is obtained with the addition of 0.02 to 0.10% vanadium, since the precipitations of vanadium carbonitrites occur mainly in the ferrite grain and not at the grain boundaries. 
     Observance of an intermediate temperature of 450° C. to 500° C. allows for completely avoiding the formation of separations. The steel exhibits a ferritic-pearlitic structure and the ratio of Cvmax to Cv100 lies between 1.0 and 1.3. Cv100 signifies the minimum notch impact value of the upper shelf which will show a 100% ductile fracture. Cvmax is the value, in dependence on the temperature, at which the highest notch impact toughness for the entire test is produced. The steel manufactured according to the present invention displays a complete lack of fracture splitting in the CVN-notch impact tests (CVN: Charpy-V-Notch) and simultaneously CVN-transition temperatures of as low as -30° C. 
     With the observance of an intermediate temperature of 500° C. to 570° C., steel of the mentioned composition exhibits a decreased number of separations. Nevertheless it still displays a substantially increased notch impact toughness values. Notch impact toughness tests involving hot strips and/or plates afflicted with separations have shown that with increased number of &#34;separations&#34; in the fracture surface of the CVN-tests the notch impact toughness (in J/cm 2 ) decreases. The basis for this decrease in the notch impact toughness lies in the fact that the separations proceed perpendicular to the main fracture surface and parallel to the sample surface, particularly before the spreading of the main tear begins, as is evident from FIG. 1, so that a small amount of energy is required for the begin of yielding, which occurs during bending of the samples in the course of the notch impact test. This is of significance to the extent that material &#34;free of separations&#34; having highest notch impact toughness values, are not always required for the production of hot strips or plates, so that use is found for material with some slight number of &#34; separations&#34;, however with increased notch impact toughness. A material of that kind will be obtained with the observance of an intermediate temperature from 500° to 570° C. 
     A steel with additions of 0.15 to 0.35% molybdenum, 0.10 to 0.35% chromium and/or 0.30 to 0.90% nickel, alone or in combination, suffices for the production of a &#34;separations-free&#34; material if the same cooling conditions of 2° to 10° C./sec also to an intermediate temperature of 550° C. are retained, so that the cooling need ensue only to this temperature. 
     For the production of a steel with said alloying, displaying a reduced number of separations but an increased notch impact toughness, it is sufficient if the intermediate temperature amounts to 550° C. to 620° C. and the finishing temperatures are lying between 750° C. and 850° C. 
     The advantage of a reduction in the number of &#34;separations&#34; insofar as the notch impact test is concerned is seen clearly in FIGS. 2 and 3. 
     For example, decrease in the ratio Cvmax to Cv100 from about 2.0 at a value of 1.3 corresponds to an increase in the notch impact toughness values in cross-section from 150 J/cm 2  to about 230 J/cm 2  among X70 quality steels alloyed with addition of molybdenum, chromium or nickel (FIG. 3), and from 160 J/cm 2  to 280 J/cm 2  for niobium-vanadium-containing steels of X70 quality (FIG. 2), which correspond to an increase in the notch impact toughness of 53 and 75% respectively. The representation of notch impact toughness as a function of the ratio of Cvmax to Cv100 was for that reason selected for FIGS. 2 and 3 since the ratio of Cvmax to Cv100 responds more sharply to the number of separations than to all other parameters. 
     The steels of Tables 1 and 2 were made in an oxygen blowing converter, and were rolled into hot strips or heavy plates according to the conditions indicated in Tables 3, 4 and 5. 
     The results obtained, represented additionally in FIGS. 4 and 5 or FIGS. 6 and 7, indicate that a distinct increase in notch impact toughness is realized in contrast to the customarily hot rolled microalloyed steels. 
     It was established that the temperature at which the hot strip or plate leaves the last finishing stand is not required to be as completely confined for a separations reduced steel according to the present invention as for the manufacture of a separations-free steel. A temperature range of 750° to 850° C. is possible. 
     According to the invention performance of the new methods with an intermediate temperature from 550° to 620° C. can be accomplished also with further addition of 0.002 to 0.08% zirconium and/or 0.004 to 0.051% cerium. 
     For the manufacture of separations-free steels, tests were carried out on eleven types of steel with different carbon contents and combinations of microalloying additives niobium, vanadium, nickel and chromium. 
     The compositions of the steels are indicated in Table 6, in which fractions of the components contained in the steel are given in percent. The melt numbers serve merely for identification of the steel. 
     The steels were manufactured according to the parameters given in Table 7. The outlet thickness, the thickness of the rolled steel plates, the pusher furnace temperature, the finishing temperature and the temperature after the controlled cooling (coiling temperature) are given. In all cases with the exception of sheet A the steel was coiled up. The last column gives the cooling rate from the finishing stand temperature (WET) to the coiling temperature (T H ) in °C./sec. In the coil the steel was then cooled down slowly, for example at a rate of about 0.5° C./hour. 
     The mechanical-technological characteristics of the examined and separations-free steels are summarized in Table 8. The letters &#34;L&#34; and &#34;Q&#34; characterize the test positions with regard to the direction of rolling, namely &#34;L&#34; a length test and &#34;Q&#34; a transverse test, for which the notch impact test was conducted. The further three columns contain the usual statements concerning yielding stress and tensile strength. The a k  -value gives the energy absorption of the steel at different points on the a k  -curve as a function of the temperature. Cv100 characterizes the energy absorption at the minimum temperature at which a complete ductile fracture is instituted. Cvmax characterizes the maximum energy absorption, whereas TU 50  is for the temperature at which in the transition region between brittle fracture and ductile fracture of the Charpy-V-notch impact test according to German Industrial Specification DIN 50.115, 50% ductile fracture is exhibited in the fracture surface. 
     The next two columns give the transition temperature for Cv100 and TU 50 . It is evident that TU 50  always lies considerably below -30° C., so that a high toughness is also guaranteed at minimum temperatures. The steel distinguishes itself by a high energy absorption. With the separations-free steel according to the invention the quotient Cvmax to Cv100 is situated close to 1, namely between 1 and 1.3. All of the steels are free of separations perpendicular to the fracture surface. 
     Whereas Tables 1 to 5 have to do with separations-poor steels according to the invention having a high notch impact toughness, Tables 6 to 8 characterize separations-free steels that, according to constitution, display a very high notch impact toughness. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of steel differing from the types described above. 
     While the invention has been illustrated and described as embodied in hot strips or heavy plates from a denitrated steel, and methods for their manufacture, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     
                                           TABLE 1__________________________________________________________________________Chemical Composition of the Tested Steels in %Melt Nr.C   Si Mn  P  S   Al N    V  Nb__________________________________________________________________________676490,11    0,34       1,61           0,019              0,008                  0,039                     0,0058                          0,09                             0,04380690,10    0,35       1,59           0,021              0,013                  0,051                     0,0057                          0,08                             0,04380700,10    0,39       1,59           0,016              0,012                  0,041                     0,0072                          0,09                             0,05399070,10    0,27       1,54           0,020              0,013                  0,037                     0,0057                          0,07                             0,04105270,09    0,26       1,58           0,015              0,003                  0,051                     0,0107                          0,07                             0,03443590,09    0,24       1,49           0,014              0,004                  0,039                     0,0108                          0,06                             0,03103810,09    0,33       1,58           0,015              0,011                  0,059                     0,0080                          0,09                             0,04101790,11    0,37       1,55           0,020              0,009                  0,055                     0,0040                          0,09                             0,05439400,11    0,31       1,53           0.017              0,010                  0,051                     0,0072                          0,08                             0,05439410,10    0,29       1,54           0,016              0,012                  0,041                     0,0057                          0,08                             0,05670080,11    0,31       1,59           0,021              0,012                  0,028                     0,0057                          0,08                             0,05671380,12    0,37       1,62           0,016              0,007                  0,067                     0,0072                          0,09                             0,06116080,10    0,38       1,56           0,020              0,003                  0,049                     0,0106                          0,08                             0,04117980,09    0,38       1,56           0,015              0,002                  0,037                     0,0084                          0,08                             0,04462770,09    0,39       1,62           0,018              0,005                  0,044                     0,0077                          0,08                             0,04462790,10    0,39       1,61           0,020              0,004                  0,036                     0,0091                          0,07                             0,04463660,08    0,36       1,60           0,020              0,006                  0,048                     0,0061                          0,07                             0,04463680,09    0,36       1,60           0,020              0,004                  0,045                     0,0088                          0,07                             0,04714450,10    0,37       1,62           0,015              0,002                  0,050                     0,0089                          0,09                             0,04714510,09    0,39       1,55           0,019              0,002                  0,030                     0,0089                          0,08                             0,04715480,09    0,33       1,57           0,015              0,004                  0,037                     0,0086                          0,08                             0,04719150,10    0,38       1,58           0,018              0,003                  0,031                     0,0092                          0,08                             0,05721480,09    0,38       1,61           0,018              0,004                  0,051                     0,0077                          0,07                             0,04722550,09    0,35       1,65           0,020              0,007                  0,039                     0,0124                          0,08                             0,04__________________________________________________________________________ 
    
     
                                           TABLE 2__________________________________________________________________________Chemical Composition of the Tested Steels in %Warmband C  Si Mn P  S  N   Al Nb V  Mo Cer                                   Zr Cr Remarks__________________________________________________________________________817/21 0,10    0,32       1,53          0,026             0,012                0,0068                    0,036                       0,07                          0,04                             0,16                                -- -- -- The chemical com-817/22 0,10    0,33       1,55          0,029             0,013                0,0069                    0,036                       0,08                          0,04                             0,15                                -- -- -- position of hot817/26 0,10    0,33       1,54          0,027             0,012                0,0070                    0,036                       0,07                          0,04                             0,15                                -- -- -- strips S, T, U, C,817/27 0,10    0,32       1,50          0,025             0,014                0,0072                    0,034                       0,10                          0,06                             0,21                                -- -- -- D and E is given817/30 0,10    0,33       1,51          0,016             0,011                0,0076                    0,044                       0,07                          0,04                             0,15                                -- -- -- in applicants&#39;886/31 0,04    0,29       1,26          0,026             0,008                0,0063                    0,034                       0,09                          -- 0,33                                0,051                                   -- -- German priority886/33 0,04    0,29       1,23          0,021             0,008                0,0058                    0,033                       0,08                          -- 0,33                                0,005                                   -- -- application886/34 0,04    0,29       1,27          0,023             0,009                0,0058                    0,034                       0,09                          -- 0,33                                0,004                                   -- -- P 29 49 124.593861 0,04    0,30       1,27          0,023             0,008                0,0055                    0,031                       0,09                          -- 0,35                                -- -- --93859 0,08    0,35       1,76          0,015             0,010                0,0059                    0,048                       0,10                          -- 0,34                                -- -- --907022 bis 0,07    0,26       1,68          0,019             0,004                0,0084                    0,048                       0,04                          0,06                             -- -- -- 0,30907024995211 0,07    0,21       1,41          0,017             0,008                0,0067                    0,035                       0,06                          -- 0,33                                -- -- --995213 0,07    0,22       1,46          0,020             0,009                0,0061                    0,028                       0,06                          -- 0,34                                -- -- --995214 0,04    0,18       1,55          0,014             0,008                0,0082                    0,036                       0,06                          -- 0,29                                -- 0,002                                      --995215 0,06    0,23       1,47          0,021             0,009                0,0058                    0,038                       0,06                          -- 0,34                                -- -- --0849/03 K* 0,13    0,35       1,60          0,019             0,002                0,0104                    0,060                       0,03                          -- -- -- -- -- *contains addition-                                         ally 0.69% Ni995219 0,04    0,18       1,51          0,013             0,007                0,0074                    0,047                       0,07                          -- 0,36                                -- 0,07                                      --995225 0,04    0,20       1,51          0,013             0,008                0,0064                    0,051                       0,07                          -- 0,37                                -- 0,07                                      --__________________________________________________________________________ 
    
     
                                           TABLE 3__________________________________________________________________________            CVN-a.sub.k -Value                         Finishing                              Coil or Nr.    Hot Strip   and/or Heavy Plate     Thickness in mm           in J/cm.sup.2 at -20° C.mumMaxi-                     ##STR1##                         temper- ature in °C.                              pile temp. in °C.                                   ΔT in °C.                                      Cooling rate °C./s                                            REMARKS__________________________________________________________________________1     2   3     45       6    7    8   9   10  11__________________________________________________________________________1  691160 13,5  113  164 1,82 790  540 250 7,202  &#34;      13,5  103  155 1,78 790  560 230 6,65                                            Melt 676493  &#34;      13,5  104  148 1,83 790  570 220 6,44  702339 13,5  128  137 1,23 790  520 270 7,75  &#34;      13,5  125  134 1,07 790  480 290 8,96  &#34;      13,5  123  129 1,05 790  500 290 8,37  &#34;      13,5  125  130 1,04 800  460 340 9,58  702340 13,5  143  145 1,18 790  510 280 8,09  &#34;      13,5  126  150 1,19 790  500 290 8,310 &#34;      13,5  126  149 1,18 790  500 290 8,3   Melt 3806911 &#34;      13,5  121  140 1,16 790  460 330 9,512 702341 13,5  124  137 1,10 790  500 290 8,313 &#34;      13,5  126  137 1,09 790  500 290 8,314 &#34;      13,5  125  143 1,14 790  470 320 9,115 &#34;      13,5  114  137 1,20 800  450 350 9,416 725534 13,5  158  172 1,42 780  510 270 8,017 725535 13,5  155  173 1,29 790  500 290 8,3   Melt 3807018 725536 13,5  158  173 1,09 800  460 340 9,519 725545 13,5  88   136 2,19 790  590 200 6,00                                            Melt 3807020 725546 13,5  91   149 2,22 780  590 190 6,0021 749682 13,5  84   132 1,94 790  600 190 5,8022 &#34;      13,5  80   130 1,83 790  590 200 6,0023 &#34;      13,5  77   123 1,81 780  600 180 6,0024 749684 13,5  127  149 1,41 800  530 270 7,425 &#34;      13,5  109  131 1,39 790  520 270 7,7   Melt 3990726 &#34;      13,5  107  130 1,41 800  530 270 7,427 749685 13,5  110  129 1,17 790  500 290 8,328 &#34;      13,5  111  132 1,19 790  490 300 8,6029 &#34;      13,5  116  145 1,25 790  500 290 8,330 996962 14,8  285  329 1,60 770  540 230 5,95                                            Melt 1052731 &#34;      14,8  296  314 1,20 780  470 310 7,8032 996963 14,8  247  276 1,51 780  530 250 6,20                                           Melt 4435933 996964 14,8  282  300 1,15 760  500 260 7,0034 &#34;      14,8  281  290 1,05 770  480 290 7,6035 996966 14,8  266  302 1,29 780  510 270 6,75                                            Melt 1052736 &#34;      14,8  246  281 1,31 780  510 270 6,7537 857749 14,8  89   142 1,89 780  630 150 4,20                                            Melt 103838 857750 14,8  89   135 2,14 780  600 180 4,70                                            Melt 101739 857751 14,8  84   140 1,92 790  600 190 4,7040 857752 14,8  104  167 1,80 780  600 180 4,7  Melt 439441 857754 14,8  152  180 1,46 760  520 240 6,50                                           Melt 103842 857755 14,8  143  191 1,34 780  500 280 7,00                                           Melt 101743 857756 14,8  157  185 1,30 770  490 280 7,15                                           Melt 439444 857764 14,8  201  201 1,26 770  500 270 7,00                                           Melt 103845 857765 14,8  163  174 1,32 760  500 260 7,00                                            Melt 101746 857766 14,8  156  185 1,34 770  490 280 7,1547 857767 14,8  176  199 1,28 770  490 280 7,15                                           Melt 439448 857768 14,8  129  188 2,09 780  590 190 4,75                                            Melt 103849 857769 14,8  128  191 1,97 770  600 170 4,7050 857770 14,8  101  164 2,25 780  600 180 4,70                                            Melt 101951 857771 14,8  119  184 2,52 790  610 180 4,5052 878523 16,0  118  145 2,16 790  580 210 4,55                                           Melt 116053 997273 16,0  122  137 1,88 790  560 230 5,00                                           Melt 714454 997300 16,0  169  199 1,89 790  550 240 5,30                                           Melt 714555 880162 16,0  134  182 1,92 780  570 210 4,70                                           Melt 1160856 997321 16,0  175  201 1,73 770  550 220 5,30                                           Melt 7154857 903190 16,0  232  277 1,36 790  510 280 6,40                                           Melt 7214858 903195 16,0  289  290 1,07 800  480 320 7,40                                           Melt 1178959 903202 16,0  165  234 1,89 800  550 250 5,30                                            Melt 7191560 903203 16,0  247  253 1,26 790  490 300 7,061 903231 16,0  154  210 1,69 810  560 250 5,00                                           Melt 4627962 906978 16,0  176  228 1,74 760  580 180 4,65                                           Melt 4636663 906992 16,0  217  237 1,21 790  490 300 7,00                                            Melt 4627764 906998 16,0  181  224 1,76 790  560 230 5,0065 909470 16,0  137  216 1,83 790  550 240 5,30                                           Melt 7225566 909484 16,0  269  280 1,14 780  490 290 7,00                                           Melt 4636867 670103 16,9  93   139 1,85 800  580 220 4,2068 670105 16,9  107  160 1,86 790  570 220 4,45                                            Melt 6700869 670107 16,9  117  159 1,97 790  560 230 4,6570 675840 16,9  184  232 1,18 800  490 310 6,90                                           Melt 67138__________________________________________________________________________ 
    
     
                                           TABLE 4__________________________________________________________________________                                              Thick-                                                  Cool-Hot Strip CVN-Value            Coil or                           ness                                                  ingand/or    in J/cm.sup.2            pile temp.                  Chemical Composition in %   in  rate                                                      MeltNr.   Heavy Plate     at -20° C.            in °C.                  C  Si Mn P  S  Al N   V  Nb mm  °C./s                                                      Nr.1  2      3      4     5  6  7  8  9  10 11  12 13 14  15  16__________________________________________________________________________1  878513 119    620   0,10                     0,36                        1,60                           0,017                              0,002                                 0,038                                    0,0110                                        0,08                                           0,04                                              16,0                                                  3,80                                                      116062  878523 118    580                               16,1                                                  4,503  880162 134    570   0,10                     0,38                        1,56                           0,020                              0,003                                 0,049                                    0,0106                                        0,08                                           0,04                                              16,0                                                  4,75                                                      116084  880162 124    570                               16,3                                                  4,605  902083 138    580   0,10                     0,37                        1,55                           0,017                              0,003                                 0,042                                    0,0065                                        0,08                                           0,04                                              15,9                                                  4,55                                                      117966  902058 191    540   0,10                     0,36                        1,57                           0,016                              0,002                                 0,029                                    0,0064                                        0,07                                           0,04                                              15,9                                                  5,60                                                      117977  903195 307    480   0,09                     0,38                        1,56                           0,015                              0,002                                 0,037                                    0,0084                                        0,08                                           0,04                                              16,3                                                  7,30                                                      117988  903195 289    480                               16,1                                                  7,409  907001 175    550   0,10                     0,36                        1,59                           0,018                              0,004                                 0,032                                    0,0092                                        0,07                                           0,04                                              16,0                                                  5,30                                                      4627810 903231 151    560   0,10                     0,39                        1,61                           0,020                              0,004                                 0,036                                    0,0091                                        0,07                                           0,04                                              16,0                                                  5,00                                                      4627911 903231 154    560                               16,1                                                  4,9512 906983 167    560   0,09                     0,36                        1,60                           0,020                              0,004                                 0,045                                    0,0088                                        0,07                                           0,04                                              16,3                                                  4,90                                                      4636813 909484 269    490                               15,9                                                  7,014 997273 122    560   0,10                     0,37                        1,62                           0,015                              0,002                                 0,050                                    0,0089                                        0,09                                           0,04                                              16,1                                                  4,95                                                      7144515 880171 252    470                               16,3                                                  7,9016 997278 139    560   0,09                     0,32                        1,60                           0,018                              0,004                                 0,033                                    0,0081                                        0,08                                           0,04                                              15,9                                                  5,10                                                      7144617 880174 236    470   0,10                     0,38                        1,66                           0,020                              0,002                                 0,050                                    0,0089                                        0,08                                           0,04                                              16,1                                                  7,70                                                      7145018 880174 240    490   0,10                     0,38                        1,66                           0,020                              0,002                                 0,050                                    0,0089                                        0,08                                           0,04                                              16,0                                                  7,0 7145019 997300 169    550                               16,1                                                  5,2520 880160 158    550   0,09                     0,39                        1,55                           0,019                              0,002                                 0,030                                    0,0089                                        0,08                                           0,04                                              16,0                                                  5,30                                                      7145121 880160 194    520                               16,2                                                  6,1022 880166 134    560   0,10                     0,40                        1,59                           0,017                              0,002                                 0,047                                    0,0089                                        0,08                                           0,04                                              16,0                                                  5,0 7145223 997329 149    550   0,09                     0,38                        1,67                           0,018                              0,002                                 0,047                                    0,0087                                        0,08                                           0,04                                              16,3                                                  5,15                                                      7151424 997337 149    570   0,10                     0,38                        1,62                           0,019                              0,004                                 0,029                                    0,0086                                        0,08                                           0,04                                              15,9                                                  4,75                                                      7151625 997321 175    550   0,09                     0,33                        1,57                           0,015                              0,004                                 0,037                                    0,0086                                        0,08                                           0,04                                              16,1                                                  5,25                                                      7154826 997324 163    540                               15,9                                                  5,6027 997309 204    530   0,09                     0,37                        1,55                           0,014                              0,003                                 0,043                                    0,0085                                        0,08                                           0,04                                              15,9                                                  5,85                                                      7154928 880161 141    590   0,10                     0,34                        1,55                           0,019                              0,003                                 0,050                                    0,0050                                        0,08                                           0,04                                              16,0                                                  4,35                                                      7155029 885026 210    500   0,09                     0,34                        1,60                           0,018                              0,003                                 0,044                                    0,0076                                        0,07                                           0,04                                              16,3                                                  6,50                                                      7169030 885023 152    570   0,08                     0,34                        1,61                           0,018                              0,003                                 0,030                                    0,0089                                        0,08                                           0,04                                              16,1                                                  4,70                                                      7169131 902052 127    600   0,10                     0,37                        1,65                           0,020                              0,003                                 0,032                                    0,0082                                        0,08                                           0,04                                              16,0                                                  4,15                                                      7169732 902064 243    510   0,09                     0,36                        1,64                           0,020                              0,003                                 0,049                                    0,0090                                        0,07                                           0,05                                              16,2                                                  6,30                                                      7191033 903214 188    550   0,09                     0,38                        1,64                           0,020                              0,004                                 0,037                                    0,0092                                        0,08                                           0,04                                              16,0                                                  5,30                                                      7191134 903227 131    590   0,10                     0,38                        1,60                           0,016                              0,003                                 0,036                                    0,0109                                        0,07                                           0,04                                              15,9                                                  4,35                                                      7191435 903202 176    540   0,10                     0,38                        1,58                           0,018                              0,003                                 0,031                                    0,0092                                        0,08                                           0,05                                              16,0                                                  5,50                                                      7191536 903202 165    550                               16,2                                                  5,2037 903203 247    490                               16,0                                                  7,0038 903218 151    560   0,10                     0,37                        1,60                           0,020                              0,003                                 0,039                                    0,0064                                        0,07                                           0,04                                              16,3                                                  4,90                                                      7191639 907018 222    540   0,10                     0,35                        1,60                           0,108                              0,003                                 0,050                                    0,0089                                        0,07                                           0,05                                              15,9                                                  5,60                                                      7214740 903190 244    500   0,09                     0,38                        1,61                           0,018                              0,004                                 0,051                                    0,0077                                        0,07                                           0,04                                              15,9                                                  6,70                                                      7214841 903190 232    510                               16,0                                                  6,4042 996961 141    600   0,09                     0,26                        1,58                           0,015                              0,003                                 0,051                                    0,0107                                        0,07                                           0,03                                              14,8                                                  4,75                                                      1052743 996961 144    590                               14,7                                                  4,9044 996962 296    470                               14,8                                                  7,8045 996964 282    500                               14,9                                                  7,046 996964 281    480                               14,7                                                  7,6047 996966 266    510                               14,8                                                  6,7548 996966 246    510                               14,7                                                  6,8049 996963 247    530   0,10                     0,24                        1,49                           0,014                              0,004                                 0,039                                    0,0108                                        0,06                                           0,03                                              14,8                                                  6,20                                                      44359__________________________________________________________________________ 
    
     
                                           TABLE 5__________________________________________________________________________          CVN-a.sub.k -Value      Thick-          in J/cm.sup.2 Test  Finishing                                   Coil or Nr.   Hot Strip and/or Heavy Plate      ness in mm           -40° C.               at upper shelf                    ##STR2##                        Position to the Axis pipe                              Temper- ature in °C.                                   pile temp. in °C.                                        ΔT in                                           Cooling rate in                                           °C./s                                                  REMARKS__________________________________________________________________________1  2       3   4    5   6    7     8    9   10  11       12__________________________________________________________________________1  886/31CE/R      15.2          80   183 2.29 60° zur RA                              820      150 3.35  Customary hot                                     670         strips or heavy2          15.2          104  231 2.22 90° zur RA                              820      150 3.35  plates, displaying3  93859 CA      18.0          85   155 1.82 60° zur RA                              790      140 2.5   a maximal num-4          18.0          94   214 2.28 90° zur RA                              790      140 2.5   ber of separa-5  817/26CE/R      14.3          92   158 1.72 60° zur RA                              800    650                                       150 4.2   tions with the6  9381 A/R      17.6          106  153 1.44 60° zur RA                              780      130 2.65  Notch Impact7  886/31CM/R      15.2          90   191 2.12 90° zur RA                              820      175 3.75  Test.8          15.2          103  231 2.24 60° zur RA                              820    645                                       175 3.759          15.2          70   113 1.61 90° zur RA                              820      175 3.7510 817/30CE/R      14.2          76   136 1.79 90° zur RA                              800   640                                       160 4.4211 886/31CA/R      15.2          50   120 2.40 90° zur RA                              820      185 3.9012         15.2          80   151 1.89 60° zur RA                              820    635                                       185 3.9013 817/21CM/R      14.9          110  162 1.47 60° zur RA                              810      175 4.214 S       18.5          118  214 1.81 60° zur RA                              750   630                                       120 2.415 817/26CM/R      14.5          82   135 1.65 90° zur RA                              810   625                                       185 4.516 907023  16.0          130  235 1.81 90° zur RA                              770      150 3.717 817/30CA/R      14.3          101  178 1.76 90° zur RA                              800    620                                       180 4.6518         14.3          101  168 1.66 90° zur RA                              800      180 4.65  19   817/30CM/R      14.4          103  160 1.55 60° zur RA                              800      185 4.75                                     61520 817/27CE/R      14.3          103  149 1.45 90° zur RA                              800      185 4.8021 907024  16.0          173  277 1.60 90° zur RA                              790      180 4.0022         16.0          171  272 1.59 90° zur RA                              790    610                                       180 4.00  According to23 817/27CM/R      14.5          107  167 1.56 60° zur RA                              800      190 4.85  the invention,24 817/27CA/R      14.5          130  187 1.44 60° zur RA                              800      195 4.90  hot strips or                                     605         heavy plates25         14.5          82   114 1.39 90° zur RA                              800      195 4.90  displaying a26 995219/CM/R      18.4          115  217 1.40 60° zur RA                              810      220 3.55  small number                                     590         of separations27         18.4          110  147 1.34 90° zur RA                              810      220 3.55  with the28 089/03 KA      17.1          186  259 1.39 60° zur RA                              820      240 4.10  Notch Impact29 907023  16.0          179  303 1.69 90° zur RA                              770      190 4.55  Test than the30         16.0          176  281 1.60 90° zur RA                              770    580                                       190 4.55  customary31 907022  16.0          138  276 2.0  90° zur RA                              800      220 4.55  hot strips32 886/33 CA      15.5          130  223 1.72 90° zur RA                              810      240 4.9033         15.5          157  223 1.42 90° zur RA                              810      240 4.9034 U       18.3          123  246 2.0  60° zur RA                              780     570                                       210 4.2035 995214CM/R      18.2          220  290 1.32 90° zur RA                              810      240 3.85  36   995214/CM/R      18.2          185  254 1.37 90° zur RA                              810      240 3.85  According to                                     570         the invention,37 886/34 CER      15.5          142  206 1.45 90° zur RA                              820      250 4.80  hot strips or38 995213 CA      18.2          222  300 1.35 60° zur RA                              830      270 4.25  heavy plates39         18.2          165  225 1.36 90° zur RA                              830    560                                       270 4.25  displaying a40 817/21 CA/R      15.0          170  228 1.34 60° zur RA                              800      240 5.00  small number41 T       18.3          131  256 1.95 60° zur RA                              850   550                                       300 6.00  of separation                                                 with the                                                 Notch Impact                                                 test than the                                                 customary hot                                                 strips  42   995214 CA      18.1          197  201 1.02 90° zur RA                              820      270 4.55  Hot strips pre-43         18.1          320  322 1.00 60° zur RA                              820      270 4.55  pared according44         18.1          322  323 1.00 60° zur RA                              820      270 4,55  to the conditions45 995215 CA      18.3          199  215 1.08 90° zur RA                              790      240 4.50  of applicants&#39;46         18.3          244  283 1.16 60° zur RA                              790    550                                       240 4.50  German priority47         18.3          254  262 1.03 60° zur RA                              790      240 4.50  application48 907023  16.0          215  277 1.29 90° zur RA                              770      220 5.30  P 29 49 124.549 817/22CM/R      14.4          145  165 1.14 60° zur RA                              800      250 6.1050 817/26CA/R      14.4          180  190 1.06 60° zur RA                              800      255 6.2051         14.4          176  198 1.13 60° zur RA                              800      255 6.2052 886/34CA/R      15.3          285  317 1.12 60° zur RA                              815    545                                       270 5.6553 D       18.3          201  247 1.23 60° zur RA                              810      265 5.40  54   886/34CM/R      15.4          264  288 1.09 60° zur RA                              825      285 5.70  Hot strips pre-55         15.4          187  240 1.28 90° zur RA                              825      285 5.70  pared according56         15.4          287  292 1.023                        60° zur RA                              825    540                                       285 5.70  to the conditions57 C       18.3          246  308 1.25 90° zur RA                              800      260 5.2   of applicants&#39;58         15.3          276  312 1.13 60° zur RA                              815      280 5.90  German priority59 886/34CA/R      15.3          287  326 1.14 60° zur RA                              815    535                                       280 5.90  application60         15.3          207  253 1.22 90° zur RA                              815      280 5.90  P 29 49 124.561 E       18.3          222  272 1.23 90° zur RA                              800   530                                       270 5.462 886/34CE/R      15.5          292  305 1.04 60° zur RA                              820      300 5.9563         15.5          226  268 1.19 90° zur RA                              820      300 5.9564 995225/CA/R      18.9          250  250 1.0  90° zur RA                              780      260 4.9565         18.9          156  165 1.06 90° zur RA                              780    520                                       260 4.9566 995225/CM/R      18.9          149  165 1.10 90° zur RA                              790      270 4.9567 907022  16.0          186  241 1.30 90° zur RA                              800      280 5.80__________________________________________________________________________ 
    
     
                                           TABLE 6__________________________________________________________________________Chemical compositions of the Tested Steels in %Hot Strip    Chemical Compositionor PlateMELT    C Si        Mn P  S  Al N  Nb                         V Mo Cr                                Ni                                  Sn Cu__________________________________________________________________________A    11294    .15      .32        1.59           .012              .003                 .054                    .0098                       .02                         --                           -- .03                                .75                                  &lt;.01                                     .05B    79486    .08      .35        1.76           .015              .010                 .048                    .0059                       .10                         --                           .34                              .02                                .01                                  &lt;.01                                     .03C    79639    .04      .30        1.27           .023              .008                 .031                    .0055                       .09                         --                           .35                              .02                                .02                                  &lt;.01                                     .05D    55161    .06      .23        1.47           .022              .007                 .040                    .0056                       .07                         --                           .33                              .01                                .02                                  &lt;.01                                     .03F    38070    .10      .34        1.59           .016              .012                 .041                    .0072                       .05                         .09                           -- .02                                .03                                  &lt;.01                                     .04G    38069    .10      .35        1.59           .021              .013                 .051                    .0057                       .04                         .08                           -- .03                                .03                                  &lt;.01                                     .04H    10381    .09      .33        1.58           .015              .011                 .059                    .0080                       .04                         .09                           -- .01                                .02                                  &lt;.01                                     .03I    43941    .10      .29        1.54           .016              .012                 .041                    .0057                       .08                         --                           -- .02                                .03                                  &lt;.01                                     .05J    10527    .09      .26        1.58           .015              .003                 .051                    .0107                       .03                         .07                           -- .02                                .03                                  &lt;.01                                     .03K    44359    .10      .24        1.49           .014              .004                 .039                    .0108                       .03                         .06                           -- .02                                .03                                  &lt;.01                                     .04L    12078    .07      .26        1.67           .019              .004                 .048                    .0084                       .04                         .06                           -- .30                                .02                                  &lt;.01                                     .03__________________________________________________________________________ 
    
     
                                           TABLE 7__________________________________________________________________________Manufacturing Conditions for &#34;Separations-free&#34; SteelsSpecies of     Outlet           Steel Plate                 Pusher Furnace                         Finishing                                Coil or                                      Cooling Rate FromSteel MELT     Thickness           Thickness                 Temperature                         Temperature                                Pile temp.                                      WET to T.sub.H__________________________________________________________________________                                      °C./SA     11294     200   20    1230    750    540   .sup. 2,5°B     79486     210   18,3  1180    790    540     5C     79639     205   18,3  1180    800    540   5,2D     55161     210   18,3  1180    810    545   5,4E         203   18,3  1180    800    530   5,4F     38070     201   13,5  1220    790    480   8,7G     38069     200   13,5  1220    800    500   8,5H     10381     200   14,8  1180    770    490   7,2I     43941     205   14,8  1180    770    485   7,5J     10527     205   14,8  1180    760    460   8,0K     44359     200   14,8  1180    770    500   7,2L     12078     200   16,0  1180    780    550   5,1__________________________________________________________________________ 
    
     
                                           TABLE 8__________________________________________________________________________The mechanical-technological characteristics of &#34;separations-free&#34;steelsCharacteristicHot     Yield       Tensile             TransitionStrip or Plate    Test Position   Stress R.sub.p0,2 Mpa       Strength R.sub.m MpaA.sub.5 %                a.sub.k -Value in J/cm.sup.2 C.sub.V.sup.100C.sub.V.s               up.maxTU.sub.50%                            Temperature in °C. C.sub.V.sup.100                           U.sub.50%                                    ##STR3##__________________________________________________________________________A  L    441 490 28,1               210 258 140 -35 -50 1.23   Q    471 587 29,4               229 259 165 -80 -45 1.13B  L    561 756 20,4               102 110 73  -35 -48 1.08   Q    610 765 18,2               40  48  26  -30 -51 1.20C  L    499 621 22,0               246 308 94  -76 -104                                   1.25   Q    539 641 19,1               64  66  58  -30 -49 1.03D  L    503 629 22,7               201 247 67  -72 -108                                   1.23   Q    518 651 18,3               80  95  62  -36 -58 1.19E  L    521 634 22,5               222 272 125 -65 -74 1.23   Q    571 660 19,8               74  79  55  -30 -52 1.06F  L    546 651 24,3               175 187 60  -30 -67 1.07   Q    589 672 12,3               49  56  34  -30 -60 1.14G  L    556 660 24,2               119 139 62  -60 -77 1.17   Q    599 689 21,6               45  50  34  -30 -65 1.11H  L    506 629 26,7               160 201 65  -60 -93 1.26   Q    551 639 23,7               58  63  30  -40 -82 1.09I  L    505 625 25,6               155 189 86  -60 -92 1.22   Q    535 635 22,1               53  59  45  -40 -57 1.11J  L    535 632 26,8               246 277 129 -80 -90 1.13   Q    560 648 22,8               154 186 80  -60 -82 1.21K  L    522 622 27,1               183 227 83  -80 -100                                   1.24   Q    565 637 23,1               152 169 65  -60 -95 1.11L  L    555 657 25,7               233 303 125 -90 -110                                   1.30   Q    616 692 21,3               140 170 70  -69 -100                                   1.21__________________________________________________________________________