Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 investigators (C. Crussard, J. Rauch and G. Jollant) and four other spectators. These specimens had been obtained froma casting of austenitic stainless steel of special, non- commercial composition, which had previously been used ina “study of martensitic transformation by deformation. This casting contained essentially: Cr = 17.8%, Ni = 7.4%, Mn = 1.56%, Si = 0.368, C = 0.050%, N = 0.0348. Two test specimens remaining from this study were used for our purposes. They were cylindrical bodies (diameter 7 ram and length 85 mm) with smooth heads of 12 mm diameter. These specimens had been subjected to quenching in air at 1050°c (1 hr in salt bath), finish machining and nitrofluoric attack, giving the body of the specimen a satiny appearance. the resulting structure is amagnetic, except for some parts of the surface layer of machining. The martensitic transfor- mation points in this state are: Ms = -40°C and Md = +90°C. These specimens had been entrusted to J. P. Girard for a few days. At the start of the session, they were marked with an electric pencil with large figures, Nos. 2 and 3, sur- rounded by an irregular circle. Another specimen, marked No. 1 in the same way, was used for another non-significant test, and will be used again later for a simulation control experi- ment. Its mark can be seen in Figure 5. This was the first time with J. P. Girard that we used specimens of this type and marked them in this manner. It was these specimens marked in this way that were recollected at the end of the test under conditions which we shall see: there was no possibility of substitution. Approved For Release 2000/08/07 : CIA-RDP96300787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 After marking, one of us (Cc. Crussard) verified the straightness of these specimens Nos. 2-and 3 by rolling them. There was no “out-of-round". He also verified their magnetic state. For this purpose, a rapid and simple method of evalu- ating the magnetization from point to point consists in using a small, power ful horseshoe magnet of Ticonal (pole areas 7 x 4 ram”, spacing 8.5 mm) suspended at the end of a small chain. To perform the measurement, we start from a position in which the magnet is in contact with the specimen and the suspension is vertical. We then pull the specimen away until the magnet detaches. By measuring the horizontal distance from the magnet to the specimen at this point D, and knowing the weight of the magnet (22 g) and the length of the suspen- sion, we can calculate the force F of separation. During this verification, which was performed on the center of the two specimens and on the heads, the distance D defined above did not exceed 2 to 3 mm, which corresponds to forces F of separa- tion on the order of 0.01 N. These forces were due to some traces of surface martensite produced by machining. After this verification, the specimens were placed on the table behind which J. P. Girard was operating (with rolled-up shirt sleeves) in the field of the video camera, which kept | them in view constantly (while J. P. Girard disposed of other specimens and made an attempt on a bar of light alloy, without leaving his seat) until the moment when the following experi- ments commenced: 13 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 (a) J. P. Girard took specimen No. 2 lightly by one head and, without exerting any force (the film confirms this), pilaced it in a tube, closed the tube with a stopper (always in front of the camera), took the closed tube full in the hand (left hand, the stopper always being visible) , and concentrated. . He then gave the tube to C. Crussard and, from this moment on, no longer touched the specimen. C. Crussard removed the specimen from the tube: it hada slight but distinct deformation close to one end. . The deforma- tion was visible to the eye, and was verified by rolling the specimen. A check with the magnet revealed strong local mag- netism close to this same end (see Table I). Since the entire operation had been filmed, there was no possibility of sub- stitution. Cc. Crussard replaced the specimen in its box for subsequent study. | (b) J. P. Girard picked up specimen No. 3, which had always remained in view. The operations were the same as for No. 2, except that a spectator obstructed the camera for a moment. After gd. P. Girard had concentrated, C. Crussard retrieved the closed tube, removed the specimen and rolled the specimen. This remained straight, although it exhibited local magnetism similar to that of specimen No. 2, this time without deformation. It was also replaced in its box for further study. 14 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 Preliminary measurements Sees s ae Measurements The next day, C. Crussard evaluated the magnetism and the deformations. The same magnet was always used for the mag- netism. The separation forces F defined above are indicated in Table I (to within ca. 0.01 N).. For the deformations Y, one of the ends was applied against a straight-edge and the distance between the other end (inner side) and the straight- edge was measured. At the start of the test, it was verified that the specimens "turned round". Figure 3 very clearly reveals the deformation close to one head. TABLE I ‘Specimen Specimen Measurement No. 2 No. 3 Deflection from one side yl (mm) 2.5 < 0.3 Deflection from the other side y2 1.7 < 0.3 Average deflection y = 44 Y2 2.1 < 0.3 Separation force F of the magnet (N): - one head 0.12* 0.03 - one end of the cylindrical body 0.15 2 0.22 ~ center 0.02 0.03 ~ other end of the cylindrical body 0.02 0.02 ~- other head 0.05 0.01 * Maximum value. 15 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 FIG. 3 Photograph of stainless steel specimen No. 2, after the experiment. Laboratory examinations Various examinations (which, moreover, were destructive) were performed on specimen No. 2. The bar was sawed electro- lytically close to the magnetic head. We were thus able to introduce the magnetic end of the cylindrical part of the bar into the coil of a Sigmatest apparatus: the specific magnet- ization at saturation was 2.8, corresponding to a proportion of 1.9% magnetic phase (a'). For specimen No. 3, a non-destructive study with x-rays revealed a' and e« martensites, the latter in high proportion, in addition to austenite in the magnetic zone. Photomicrographs (specimen No. 2) on the surface polished mechanically and then electrolytically (Figures 4a and 4b) 16 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 VICKERS HARDNESS _— Plate VG (™») 8 Load: 2,94 daN ' Marked face be 10315) 5 . eg e (120 Unmarked face Distance to the marked end 1100 a _ rt ty 50 wo 150. (mm) o before : Hardness at half length the experiment . + after . FIG. 8 Hardness measured on both faces of the | light-alloy specimen VG, before and after the test. We see that the maximum hardenings observed range from 63 (test 4) to 12% (test 2), and that they are 8% on average. For test 4, we had made six Vickers impressions at half- length before the experiment because, in the preceding tests, the hardening had always occurred in this zone, giving hard- nesses of 1200 to 1210, which permits us completely to eliminate 26 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 Table III Face 2 1290 1200 {9) 1200 (10) itial hard igniti Maximum hardness Initial hardness Signiticanty ‘ '« in the modified zone Test Specimen . (MPa) . End of Reference length 3 plate (standard deviation) {mm) 1 1-1 Face 1 1340 1240 1220 (15) 20 Face 2 (R) 1290 1200 1230 (14) 30 2 11-J Face 1 1340 1180 "4480. (20) 20 Face 2 (R) 1310 1190 1200 (21) | 20 3 " 44-H Face 1 1420 1290 20 Face 2 (R) 1380 1260 | 15 — 4 VG Face 1 (R) 1270 1200 (7) 1210 (15) | , 35 i 35 the hypothesis of a pre-existing heterogeneity of hardness. We should note in passing that this test is particularly in- teresting, since it was performed in England, in the laboratory of Professor J. Hasted, and that the hardnesses were remeasured "blind" and confirmed in an independent English laboratory at the Electrical Research Association. INTERNAL STRESSES: Two techniques were used to detect possible differences in longitudinal residual stresses of the modified zones. The technique of surface measurement by x-ray diffraction (sin? w method), used on specimen 11-I, indicated a large modification of the longitudinal residual stress on the two opposite faces of the modified zone: in fact, we observed a residual stress of -80 MPa on the unmarked face (slightly concave) and of +80 MPa on the opposite fiber (marked). At the unmodified ends, Approved For Release 2000/08/07 : CIA-RDP9600787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 we found the initial stress condition which is normal for this metallurgical State (T3511), i.e. oR * 15 MPa. | This point was confirmed by measuring the relative defor- mations produced on face 2 of specimen 11l-J by progressive chemical shaping of the entire opposite face (1). By this technique (the Rosenthal-Norton technique), we observed a large and significant variation of the gauge situated verti- cally above the modified zone, although a gauge situated on the same fiber, 25 mm from the modified zone, exhibited normal behavior Similar to that of the two gauges situated on the reference. We can therefore conclude without ambiguity that the local modification of hardness is associated with a local modification of the residual stress condition of this zone. MICROSTRUCTURE : The specimens modified during tests 1 and 2, together with the corresponding reference specimens, were examined by the transmission electron microscope (100 kV). Thin laminas parallel to the surface and carefully machined down to avoid any deformation were sampled at half thickness and on the two opposite faces of the modified zone of specimen l1-I, and also on the modified surface zone (face 2) of specimen l1l-J. | In both cases, we observed that the modified zones ex- hibited a characteristic microstructure consisting of a very high density of small dislocation loops with diameter of ca. 200 A (Figures 9a, 10a and 10b). At half thickness, the density of loops was less, but was significantly greater than Approved For Release 2000/08/07 : CIA-RDP964%787R000500160001-1
Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 Table IV sss ESP TGA cesioenmneneneenee re ; . Density of visible Sampling loops * Relative density com- pared with reference (cm-3) 11-1 (reference) HV = 1240 74.1013 . tt » 4 facet 4 modified zone $ HV = 1340 130 .10 18 11.1 ; face 2 “ats modified zone ' HV = 1290 84 .10 1 14-1 half-thickness Bt 1083 8 in the initial metal sampled at the end of the specimen and from a reference specimen. In the case of specimen ll-I, we made a comparative count of the loops which were visible in the (110) section, with g = [111] s > 0. After having measured the respective thick- nesses of the different laminas, we found the results given in Table IV (average of five fields). In summary, we observed that the modifications produced by J. P. Girard on duralumin plates submitted to him simul- taneously involved: - a surface hardening on the order of 8%, localized on the two faces of the plates, over a length which can attain 40 mm and a width of 10 to 15 mm; ~- modification of the surface residual stresses in the modified zone; ~ the creation, in this zone, of a particular micro- structure, consisting of a very high density of small dis- location loops (diameter = 200 A); - 29 Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1
ii i | Approved For Release 2000/08/07 : CIA-RDP96-00787R000500160001-1 - the absence of macroscopic bending deformation (except for test 1 -- see above). Simulation tests As in the case of stainless steel, we searched for double ssurance by trying to conceive of simple methods of defor- mation which could simulate the preceding states. Let us note first that the electron photomicrographs show that the Guinier-Preston zones are not dissolved and are the game at the end of the test as during the original state. This rules out any simulation by thermal treatment, specifically by surface heating (inductive or radiative) . We were therefore led to conceive of mechanical simulation tests. ALTERNATING BENDING Considering that manual contact had been permitted during the first step of the experiment, we could ask whether a sur- | reptitious operation of alternating bending in the plastic domain might be sufficient to lead to the observed modifica- tions. | | Alternating bending tests on reference specimens permitted | us to see that it was necessary to introduce a total plastic deformation of at least 5% by alternating bending to obtain hardening on the order of that observed previously (ca. 8%). Approved For Release 2000/08/07 : CIA-RDP96-B0787R000500160001-1