FREE-CUTTING COPPER ALLOY

Abstract: Free-cutting alloys with industrially satisfactory machinability comprising 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon; 0.02 to 0.4, by weight, of lead and the remaining percent, by weight, of zinc.

Description: BACKGROUND OF THE INVENTION 1. Field of The Invention The present invention relates to free-cutting copper alloys. 2. Prior Art Among the copper alloys with a good machinability are bronze alloys such as the one under JIS designation H5111 BC6 and brass alloys such as the ones under JIS designations H3250-C3604 and C3771. Those alloys are so enhanced in machinability with the addition of 1.0 to 6.0 percent, by weight, of lead as to give industrially satisfactory results as easy-to-work copper alloy. Because of their excellent machinability, those lead-contained copper alloys have been an important basic material for a variety of articles such as city water faucets, water supply/drainage metal fittings and valves. In those conventional free-cutting copper alloys, lead does not form a solid solution in the matrix but disperses in granular form, thereby improving the machinability of those alloys. To produce the desired results, lead has to be added in as much as 2.0 or more percent by weight. If the addition of lead is less than 1.0 percent by weight, chippings will be spiral in form as (D) in Fig. 1. Spiral chippings cause various troubles such as, for example, tangling with the tool. If, on the other hand, the content of lead is 1.0 or more percent by weight and not larger than 2.0 percent by weight, the cut surface will be rough, though that will produce some results such as reduction of the cutting resistance. It is usual, therefore, that lead is added in not smaller than 2.0 percent by weight. Some expanded copper alloys in which a high degree of cutting property is required are mixed with some 3.0 or more percent, by weight, of lead. Further, some bronze castings have a lead content of as much as some 5.0 percent, by weight. The alloy under the JIS H 5111 BC6, for example, contains some 5.0 percent, by weight, of lead. However, the application of those lead-mixed alloys has been greatly limited in recent years, because lead contained therein is harmful to humans as an environment pollutant. That is, the lead-contained alloys pose a threat to human health and environmental hygiene because lead finds its way in metallic vapor that generates in the steps of processing those alloys at high temperatures such as melting and casting and there is also danger that lead contained in the water system metal fittings, valves and others made of those alloys will dissolve out into drinking water. On that ground, the United States and other advanced nations have been moving to tighten the standards for lead-contained copper alloys to drastically limit the permissible level of lead in copper alloys in recent years. In Japan, too, the use of lead-contained alloys has been increasingly restricted, and there has been a growing call for development of free-cutting copper alloys with a low lead content. The publication by R. Mannheim et al., "Silicon brass : an alternative for lead-free faucets and fittings", Congress Anual - Associaco Brasileira de Metalurgia e materiais (1998), volume date 1997, 52nd (II Congresso International de Tecnologia Metalurgica e de materiais) discloses an evaluation of the alloy C87800 (a Si-brass) as an alternative for lead-free brass. SUMMARY OF THE INVENTION It is an object of the present invention to provide a free-cutting copper alloy which contains an extremely small amount (0.02 to 0.4 percent by weight) of lead as a machinability improving element, yet is quite excellent in machinability, can be used as safe substitute for the conventional easy-to-cut copper alloy with a large content of lead, and presents no environmental hygienic problems while permitting the recycling of chippings, thus providing a timely answer to the mounting call for restriction of lead-contained products. It is an another object of the present invention to provide a free-cutting copper alloy which has a high corrosion resistance coupled with an excellent machinability and is suitable as basic material for cutting works, forgings, castings and others, thus having a very high practical value. The cutting works, forgings, castings and others include city water faucets, water supply/drainage metal fittings, valves, stems, hot water supply pipe fittings, shaft and heat exchanger parts. It is yet another object of the present invention to provide a free-cutting copper alloy with a high strength and wear resistance coupled with an easy-to-cut property which is suitable as basic material for the manufacture of cutting works, forgings, castings and other uses requiring a high strength and wear resistance such as, for example, bearings, bolts, nuts, bushes, gears, sewing machine parts and hydraulic system parts, hence has a very high practical value. It is a further object of the present invention to provide a free-cutting copper alloy with an excellent high-temperature oxidation resistance combined with an easy-to-cut property which is suitable as basic material for the manufacture of cutting works, forgings, castings and other uses where a high thermal oxidation resistance is essential, e.g. nozzles for kerosene oil and gas heaters, burner heads and gas nozzles for hot-water dispensers, hence has a very high practical value. The objects of the present inventions are achieved by provision of the following copper alloys: 1. A free-cutting copper alloy with an excellent easy-to-cut feature which is composed of 69 to 79 percent, by weight, of copper, 2.0 to 4.0 percent, by weight, of silicon, 0.02 to 0.4 percent, by weight, of lead, and the remaining percent, by weight, of zinc wherein the metal structure of the free-cutting copper alloy has at least one phase selected from the γ(gamma) and κ(kappa) phases. For purpose of simplicity, this copper alloy will be hereinafter called the "first alloy". Lead forms no solid solution in the matrix but disperses in a granular form to improve the machinability. Silicon raises the easy-to-cut property by producing a gamma phase (in some cases, a kappa phase) in the structure of metal. That way, both are the same in that they are effective in improving the machinability, though they are quite different in contribution to the properties of the alloy. On the basis of that recognition, silicon is added to the first invention alloy so as to bring about a high level of machinability meeting the industrial requirements, while making it possible to reduce greatly the lead content. That is, the first invention alloy is improved in machinability through formation of a gamma phase with the addition of silicon. The addition of less than 2.0 percent, by weight, of silicon can not form a gamma phase sufficient enough to secure an industrially satisfactory machinability. With the increase in the addition of silicon, the machinability improves. But with the addition of more than 4.0 percent, by weight, of silicon, the machinability will not go up in proportion. The problem is, however, that silicon is high in melting point and low in specific gravity and also liable to oxidize. If silicon in a single form is fed into the furnace in the melting step, silicon will float on the molten metal and is oxidized into oxides of silicon or silicon oxide, hampering the production a silicon-contained copper alloy. In producing the ingot of silicon-contained copper alloy, therefore, silicon is usually added in the form of a Cu-Si alloy, which boosts the production cost. In the light of the cost of making the alloy, too, it is not desirable to add silicon in a quantity exceeding the saturation point or plateau of machinability improvement - 4.0 percent by weight. An experiment showed that when silicon is added in the amount of 2.0 to 4.0 percent, by weight, it is desirable to hold the content of copper at 69 to 79 percent, by weight, in consideration of its relation to the content of zinc in order to maintain the intrinsic properties of the Cu-Zn alloy. For this reason, the first invention alloy is composed of 69 to 79 percent, by weight, of copper and 2.0 to 4.0 percent, by weight, of silicon respectively. The addition of silicon improves not only the machinability but also the flow of the molten metal in casting, strength, wear resistance, resistance to stress corrosion cracking, high-temperature oxidation resistance. Also, the ductility and dezincing corrosion resistance will be improved to some extent. The addition of lead is set at 0.02 to 0.4 percent by weight on this ground. In the first invention alloy, a sufficient level of machinability is obtained by adding silicon that has the aforesaid effect even if the addition of lead is reduced. Yet, lead has to be added in the amount not smaller than 0.02 percent by weight if the alloy is to be superior to the conventional free-cutting copper alloy in machinability, while the addition of lead exceeding 0.4 percent would have adverse effects, resulting in a rough surface condition, poor hot workability such as poor forging behavior and low cold ductility. Meanwhile, it is expected that such a small content of not higher than 0.4 percent by weight will be able to clear the lead-related regulations however strictly they are to be stipulated in the advanced nations including Japan in the future. On that ground, the addition range of lead is set at 0.02 to 0.4 percent by weight in the first and also second to eighth alloys which will be described later. The first alloy may further comprise one selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; and the remaining percent, by weight, of zinc. This second copper alloy will be hereinafter called the "second alloy". That is, the second alloy is composed of the first invention alloy and, in addition, one selected element from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium. Bismuth, tellurium and selenium as well as lead do not form a solid solution with the matrix but disperse in granular form to enhance the machinability. That makes up for the reduction of the lead content. The addition of any one of those elements along with silicon and lead could further improve the machinability beyond the level hoped from the addition of silicon and lead. From this finding, the second alloy is worked out in which one element selected from among bismuth, tellurium and selenium is mixed. The addition of bismuth, tellurium or selenium as well as silicon and lead could make the copper alloy so machinable that complicated forms could be freely cut out at a high speed. But no improvement in machinability can be realized from the addition of bismuth, tellurium or selenium in the amount less than 0.02 percent, by weight. Meanwhile, those elements are expensive as compared with copper. Even if the addition exceeds 0.4 percent by weight, the proportional improvement in machinability is so small that the addition beyond that does not pay off economically. What is more, if the addition is more than 0.4 percent by weight, the alloy will deteriorate in hot workability such as forgeability and cold workability such as ductility. While it might be feared that heavy metals like bismuth would cause a problem similar to that of lead, a very small addition of less than 0.4 percent by weight is negligible and would present no particular problems. From those considerations, the second' alloy is prepared with the addition of bismuth, tellurium or selenium kept to 0.02 to 0.4 percent by weight. In this regard, it is desired to keep the combined content of lead and bismuth, tellurium or selenium to not higher than 0.4 percent by weight. That is because if the combined content exceeds 0.4 percent by weight, if slightly, then there will begin a deterioration in hot workability and cold ductility and also there is fear that the form of chippings will change from (B) to (A) in Fig. 1. But the addition of bismuth, tellurium or selenium, which improves the machinability of the copper alloy though a mechanism different from that of silicon as mentioned above, would not affect the proper contents of copper and silicon. On this ground, the contents of copper and silicon in the second alloy are set at the same level as those in the first alloy. weight, of zinc. This fourth copper alloy will be hereinafter called the "fourth invention alloy". The fourth invention alloy has any one selected from among 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium in addition to the components in the third invention alloy. The grounds for mixing those additional elements and setting those amounts to be added are the same as given for the second invention alloy. The first alloy may further comprise at least one element selected from 0.3 to 3.5 percent, by weight, of tin, 0.02 to 0.25 percent, by weight, of phosphorus, 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic, and the remaining percent, by weight, of zinc. This third copper alloy will be hereinafter called the "third alloy". The third alloy has, in addition to the first alloy, at least one element selected from among 0.3 to 3.5 percent, by weight, of tin, 0.02 to 0.25 percent, by weight, of phosphorus, 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic. Tin is effective in improving not only the machinability but also corrosion resistance properties (dezincification corrosion resistance) and forgeability. In other words, tin improves the corrosion resistance in the alpha phase matrix and, by dispersing the gamma phase, the corrosion resistance, forgeability and stress corrosion cracking resistance. The third alloy is thus improved in corrosion resistance by the property of tin and in machinability mainly by adding silicon. Therefore, the contents of silicon and copper in this' alloy are set at the same as those in the first invention alloy. To raise the corrosion resistance and forgeability, on the other hand, tin would have to be added in the amount of at least 0.3 percent by weight. But even if the addition of tin exceeds 3.5 percent by weight, the corrosion resistance and forgeability will not improve in proportion to the amount added of tin. It is no good economy. Phosphorus disperses the gamma phase uniformly and at the same time refines the crystal grains in the alpha phase in the matrix, thereby improving the machinability and also the corrosion resistance properties (dezincification corrosion), forgeability, stress corrosion cracking resistance and mechanical strength. The third alloy is thus improved in corrosion resistance and others through the action of phosphorus and in machinability mainly by adding silicon. The addition of phosphorus in a very small quantity, that is, 0.02 or more percent by weight could produce results. But the addition in more than 0.25 percent by weight would not be so effective as hoped from the quantity added. Rather, that would reduce the hot forgeability and extrudability. Just as phosphorus, antimony and arsenic in a very small quantity - 0.02 or more percent by weight - are effective in improving the dezincification corrosion resistance and other properties. But the addition exceeding 0.15 percent by weight would not produce results in proportion to the quantity added. Rather, it would affect the hot forgeability and extrudability as phosphorus applied in excessive amounts. Those observations indicate that the third alloy is improved in machinability and also corrosion resistance and other properties by adding at least one element selected from among tin, phosphorus, antimony and arsenic (which improve corrosion resistance) in quantities within the aforesaid limits in addition to the same quantities of copper and silicon as in the first invention copper alloy. In the third alloy, the additions of copper and silicon are set at 69 to 79 percent by weight and 2.0 to 4.0 percent by weight respectively - the same level as in the first alloy in which any other machinability improver than silicon and a small amount of lead is not added - because tin and phosphorus work mainly as corrosion resistance improver like antimony and arsenic. The first alloy may further comprise at least one element selected from, 0.3 to 3.5 percent, by weight, of tin, 0.02 to 0.25 percent, by weight, of phosphorus, 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic; one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; and the remaining percent, by weight, of zinc. This sixth copper alloy will be hereinafter called the "fourth alloy". The fourth alloy has any one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium in addition to the components in the fifth invention alloy. The machinability is improved by adding, in addition to silicon and lead, any one element selected from among bismuth, tellurium and selenium as in the second invention alloy and the corrosion resistance and other properties are raised by adding at least one selected from among tin, phosphorus, antimony and arsenic as in the fifth invention alloy. Therefore, the additions of copper, silicon, bismuth, tellurium and selenium are set at the same levels as those in the second invention alloy, while the additions of tin, phosphorus, antimony and arsenic are adjusted to those in the fifth invention alloy. The first alloy may further comprise 0.1 to 1.5 percent, by weight, of aluminum, and 0.02 to 0.25 percent, by weight, of phosphorus, and the remaining percent, by weight, of zinc. The fifth copper alloy will be hereinafter called the "fifth alloy". Aluminum is an element which improves the strength, machinability, wear resistance and also high-temperature oxidation resistance. Silicon, too, has a property of enhancing the machinability, strength, wear resistance, resistance to stress corrosion cracking and also high-temperature oxidation resistance. Aluminum works to raise the high-temperature oxidation resistance when it is used together with silicon and that in not smaller than 0.1 percent by weight. But even if the addition of aluminum increases beyond 1.5 percent by weight, no proportional results can be expected. For this reason, the addition of aluminum is set at 0.1 to 1.5 percent by weight. Phosphorus is added to enhance the flow of molten metal in casting. Phosphorus also works for improvement of the aforesaid machinability, dezincification corrosion resistance and also high-temperature oxidation resistance in addition to the flow of molten metal. Those effects are exhibited when phosphorus is added in the amount not smaller than 0.02 percent by weight. But even if phosphorus is used in more than 0.25 percent by weight, it will not result in a proportional increase in effect rather weakening the alloy. For this consideration, the addition of phosphorus settles down on 0.02 to 0.25 percent by weight. While silicon is added to improve the machinability as mentioned above, it is also capable of improving the flow of molten metal like phosphorus. The effect of silicon in improving the flow of molten metal is exhibited when it is added in the amount of not smaller than 2.0 percent by weight. The range of the addition for the flow improvement overlaps that for improvement of the machinability. These taken into consideration, the addition of silicon is set to 2.0 to 4.0 percent by weight. The first alloy may further comprise 0.1 to 1.5 percent, by weight, of aluminum; 0.02 to 0.25 percent, by weight, of phosphorus; one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; and the remaining percent, by weight, of zinc. The sixth alloy will be hereinafter called'the "sixth alloy". The sixth alloy contains one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium and 0.02 to 0.4 percent, by weight, of selenium in addition to the components of the fifth alloy. While a high-temperature oxidation resistance as good as in the fifth alloy is secured, the machinability is further improved by adding one element selected from among bismuth and other elements which are as effective as lead in raising the machinability. The first alloy may further comprise 0.1 to 1.5 percent, by weight, of aluminum; 0.02 to 0.25 percent, by weight, of phosphorus; at least one selected from 0.02 to 0.4 percent, by weight, of chromium and 0.02 to 0.4 percent, by weight, of titanium; and the remaining percent, by weight, of zinc. The tenth copper alloy will be hereinafter called the "seventh alloy". Chromium and titanium are intended for improving the high-temperature oxidation resistance. Good results can be expected especially when they are added together with aluminum to produce a synergistic effect. Those effects are exhibited when the addition is no less than 0.02 percent by weight, whether they are added alone or in combination. The saturation point is 0.4 percent by weight. For consideration of such observations, the seventh alloy has at least one element selected from among 0.02 to 0.4 percent by weight of chromium and 0.02 to 0.4 percent by weight of titanium in addition to the components of the fifth alloy and thus further improved over the fifth alloy with regard to the high-temperature oxidation resistance. The first alloy may further comprise 0.1 to 1.5 percent, by weight, of aluminum; 0.02 to 0.25 percent, by weight, of phosphorus; at least one element selected from among 0.02 to 0.4 percent, by weight, of chromium and 0.02 to 0.4 percent, by weight, of titanium; one element selected from among 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium and 0.02 to 0.4 percent, by weight, of selenium; and the remaining percent, by weight, of zinc. The eighth alloy will be hereinafter called the "eighth alloy". The eighth alloy contains any one selected from among 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium and 0.02 to 0.4 percent, by weight, of selenium in addition to the components of the seventh alloy. While as high a high-temperature oxidation resistance as in the tenth invention alloy is secured, the eleventh invention alloy is further improved in machinability by adding one element selected from among bismuth and other elements which are as effective as lead in raising the machinability. A free-cutting copper alloy also with further improved easy-to-cut feature obtained by subjecting any one of the preceding respective invention alloys to a heat treatment for 30 minutes to 5 hours at 400 to 6000C. The ninth alloy will be hereinafter called the "ninth alloy". The first to eighth alloys contain machinability improving elements such as silicon and have an excellent machinability because of the addition of such elements. The effect of those machinability improving elements could be further enhanced by heat treatment. For example, the first to eighth invention alloys which are high in copper content with gamma phase in small quantities and kappa phase in large quantities undergo a change in phase from the kappa phase to the gamma phase in a heat treatment. As a result, the gamma phase is finely dispersed and precipitated, and the machinability is improved. In the manufacturing process of castings, expanded metals and hot forgings in practice, the materials are often force-air-cooled or water cooled depending on the forging conditions, productivity after hot working (hot extrusion, hot forging etc.), working environment and other factors. In such cases, with the first to eleventh invention alloys, the alloys with a low content of copper in particular are rather low in the content of the gamma phase and contain beta phase. In a heat treatment, the beta phase changes into gamma phase, and the gamma phase is finely dispersed and precipitated, whereby the machinability is improved. But a heat treatment temperature at less than 4000C is not economical and practical in any case, because the aforesaid phase change will proceed slowly and much time will be needed. At temperatures over 6000C, on the other hand, the kappa phase will grow or the beta phase will appear, bringing about no improvement in machinability. From the practical viewpoint, therefore, it is desired to perform the heat treatment for 30 minutes to 5 hours at 400 to 6000C. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 shows perspective views of cuttings formed in cutting a round bar of copper alloy by lathe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 As the first series of examples of the present invention, cylindrical ingots with compositions given in Tables 1 to 15, each 100 mm in outside diameter and 150 mm in length, were hot extruded into a round bar 15 mm in outside diameter at 750 C to produce the following test pieces: first alloys Nos. 1001 to 1007, second alloys Nos. 2001 to 2006, third alloys Nos. 5001 to 5020, fourth alloys Nos. 6001 to 6045, fifth alloys Nos. 8001 to 8008, sixth alloys Nos. 9001 to 9006, seventh alloys Nos. 10001 to 10008, and eighth alloys Nos. 11001 to 11011. Also, cylindrical ingots with the compositions given in Table 16, each 100 mm in outside diameter and 150 mm in length, were hot extruded into a round bar 15 mm in outside diameter at 750°C to produce the following test pieces: ninth alloy Nos. 12001 to 12004. That is, No. 12001 is an alloy test piece obtained by heat-treating an extruded test piece with the same composition as first invention alloy No. 1006 for 30 minutes at 580°C. No. 12002 is an alloy test piece obtained by heat-treating an extruded test piece with the same composition as No. 1006 for two hours at 450°C. No. 12003 is an alloy test piece obtained by heat-treating an extruded test piece with the same composition as first invention alloy No. 1007 under the same conditions as for No. 12001 - for 30 minutes at 580°C. No. 12004 is an alloy test piece obtained by heat-treating an extruded test piece with the same composition as No. 1007 under the same conditions as for No. 12002 - for two hours at 4500C. As comparative examples, cylindrical ingots with the compositions as shown in Table 17, each 100 mm in outside diameter and 150 mm in length, were hot extruded into a round bar 15 mm in outside diameter at 7500C to obtain the following round extruded test pieces: Nos. 13001 to 13006 (hereinafter referred to as the "conventional alloys"). No. 13001 corresponds to the alloy "JIS C 3604", No. 13002 to the alloy "CDA C 36000", No. 13003 to the alloy "JIS C 3771" and No. 13004 to the alloy "CDA C 69800". No. 13005 corresponds to the alloy "JIS C 6191". This aluminum bronze is the most excellent of the expanded copper alloys under the JIS designations with regard to strength and wear resistance. No. 13006 corresponds to the naval brass alloy "JIS C 4622" and is the most excellent of the expanded copper alloys under the JIS designations with regard to corrosion resistance. To study the machinability of the first to ninth alloys in comparison with the conventional alloys, cutting tests were carried out. In the tests, evaluations were made on the basis of cutting force, condition of chippings, and cut surface condition. The tests were conducted this way: The extruded test pieces thus obtained were cut on the circumferential surface by a lathe provided with a point noise straight tool at a rake angle of - 8 degrees and at a cutting rate of 50 meters/minute, a cutting depth of 1.5 mm, a feed of 0.11 mm/rev. Signals from a three-component dynamometer mounted on the tool were converted into electric voltage signals and recorded on a recorder. The signals were then converted into the cutting resistance. It is noted that while, to be perfectly exact, the amount of the cutting resistance should be judged by three component forces - cutting force, feed force and thrust force, the judgement was made on the basis of the cutting force (N) of the three component forces in the present example. The results are shown in Table 18 to Table 33. Furthermore, the chips from the cutting work were examined and classified into four forms (A) to (D) as shown in Fig. 1. The results are enumerated in Table 18 to Table 33. In this regard, the chippings in the form of a spiral with three or more windings as (D) in Fig. 1 are difficult to process, that is, recover or recycle, and could cause trouble in cutting work as, for example, getting tangled with the tool and damaging the cut metal surface. Chippings in the form of a spiral arc from one with a half winding to one with two windings as shown in (C), Fig. 1 do not cause such serous trouble as the chippings in the form of a spiral with three or more windings yet are not easy to remove and could get tangled with the tool or damage the cut metal surface. In contrast, chippings in the form of a fine needle as (A) in Fig. 1 or in the form of arc shaped pieces as (B) will not present such problems as mentioned above and are not bulky as the chippings in (C) and (D) and easy to process. But fine chippings as (A) still could creep in on the slide table of a machine tool such as a lathe and cause mechanical trouble, or could be dangerous because they could stick into the worker's finger, eye or other body parts. Those taken into account, when judging machinability, the alloy with the chippings in (B) is the best, and the second best is the one with the chippings in (A). Those with the chippings in (C) and (D) are not good. In Table 18 to Table 33, the alloys with the chippings shown in (B), (A), (C) and (D) are indicated by the symbols "⊗", "○", "Δ" and "x" respectively. In addition, the surface condition of the cut metal surface was checked after cutting work. The results are shown in Table 18 to Table 33. In this regard, the commonly used basis for indication of the surface roughness is the maximum roughness (Rmax). While requirements are different depending on the application field of brass articles, the alloys with Rmax < 10 microns are generally considered excellent in machinability. The alloys with 10 microns ≤ Rmax < 15 microns are judged as industrially acceptable while those with Rmax ≥ 15 microns are taken as poor in machinability. In Table 18 to Table 33, the alloys with Rmax < 10 microns are marked "○"; those with 10 microns ≤ Rmax < 15 microns are indicated in "Δ" and those with Rmax ≥ 15 microns are represented by a symbol "x". As is evident from the results of the cutting tests shown in Table 18 to Table 33, the following invention alloys are all equal to the conventional lead-contained alloys Nos. 13001 to 13003 in machinability: first alloys Nos. 1001 to 1007, second alloys Nos. 2001 to 2006, third alloys Nos. 5001 to 5020, fourth alloys Nos. 6001 to 6045, fifth alloys Nos. 8001 to 8008, sixth alloys Nos. 9001 to 9006, seventh alloys Nos. 10001 to 10008, eighth alloys Nos. 11001 to 11011, ninth alloys Nos. 12001 to 12004. Especially with regard to the form of chippings, those invention alloys are favorably compared not only with the conventional alloys Nos. 13004 to 13006 with a lead content of not higher than 0.1 percent by weight but also Nos. 13001 to 13003 which contain large quantities of lead. Also to be noted is that the ninth alloys Nos. 12001 to 12004, which are obtained by heat-treating the first invention alloys Nos. 1006 and 1007, are improved over the first alloys in machinability. It is understood that a proper heat treatment could further enhance the machinability of the first to eighth alloys, depending upon the alloy compositions and other conditions. In another series of tests, the first to ninth alloys were examined in comparison with the conventional alloys in hot workability and mechanical properties. For the purpose, hot compression and tensile tests were conducted the following way. First, two test pieces, first and second test pieces, in the same shape 15 mm in outside diameter and 25 mm in length were cut out of each extruded test piece obtained as described above. In the hot compression tests, the first test piece was held for 30 minutes at 7000C, and then compressed at the compression rate of 70 percent in the direction of axis to reduce the length from 25 mm to 7.5 mm. The surface condition after the compression (7000C deformability) was visually evaluated. The results were given in Table 18 to Table 33. The evaluation of deformability was made by visually checking for cracks on the side of the test piece. In Table 18 to Table 33, the test pieces with no cracks found are marked "○"; those with small cracks are indicated by "Δ" and those with large cracks are represented by a symbol "x". The second test pieces were put to a tensile test by the commonly practiced test method to determine the tensile strength, N/mm 2 and elongation, %. As the test results of the hot compression and tensile tests in Table 18 to Table 33 indicate, it was confirmed that the first to ninth invention alloys are equal to or superior to the conventional alloys Nos. 13001 to 13004 and No. 13006 in hot workability and mechanical properties and are suitable for industrial use. The first to ninth alloys were put to dezincification corrosion and stress corrosion cracking tests in accordance with the test methods specified under "ISO 6509" and "JIS H 3250" respectively to examine the corrosion resistance and resistance to stress corrosion cracking in comparison with the conventional alloys. In the dezincing corrosion test by the "ISO 6509" method, the test piece taken from each extruded test piece was imbedded laid in a phenolic resin material in such a way that the exposed test piece surface is perpendicular to the extrusion direction of the extruded test piece. The surface of the test piece was polished with emery paper No. 1200, and then ultrasonic-washed in pure water and dried. The test piece thus prepared was dipped in a 12.7 g/l aqueous solution of cupric chloride dihydrate (CuCl 2 •2H 2 O) 1.0% and left standing for 24 hours at 750C. The test piece was taken out of the aqueous solution and the maximum depth of dezincing corrosion was determined. The measurements of the maximum dezincification corrosion depth are given in Table 18 to Table 25 and Table 28 to Table 33. As is clear from the results of dezincification corrosion tests shown in Table 18 to Table 25 and Table 28 to Table 33, the first to fourth invention alloys and the fifth. to ninth alloys are excellent in corrosion resistance in comparison with the conventional alloys Nos. 13001 to 13003 which contain great amounts of lead. And it was confirmed that especially the third and fourth alloys whose improvement in both machinability and corrosion resistance has been intended are very high in corrosion resistance in comparison with the conventional alloy No. 13006, a naval brass which is the most resistant to corrosion of all the expanded alloys under the JIS designations. In the stress corrosion cracking tests in accordance with the test method described in "JIS H 3250", a 150-mm-long test piece was cut out from each extruded material. The test piece was bent with the center placed on an arc-shaped tester with a radius of 40 mm in such a way that one end forms an angle of 45 degrees with respect the other end. The test piece thus subjected to a tensile residual stress was degreased and dried, and then placed in an ammonia environment in the desiccator with a 12.5% aqueous ammonia (ammonia diluted in the equivalent of pure water). To be exact, the test piece was held some 80 mm above the surface of aqueous ammonia in the desiccator. After the test piece was left standing in the ammonia environment for 2 hours, 8 hours and 24 hours, the test piece was taken out from the desiccator, washed in sulfuric acid solution 10% and examined for cracks under a magnifier of 10 magnifications. The results are given in Table 18 to Table 25 and Table 28 to Table 33. In those tables, the alloys which developed clear cracks when held in the ammonia environment for two hours are marked "xx." The test pieces which had no cracks at two hours but were found clearly cracked in 8 hours are indicated in "x." The test pieces which had no cracks in 8 hours, but were found clearly to have cracks in 28 hours are identified by the symbol "Δ". The test pieces which were found to have no cracks at all in 24 hours are given a symbol "o". As is indicated by the results of the stress corrosion cracking test given in Table 18 to Table 25 and Table 28 to Table 33, it was confirmed that not only the fifth and sixth invention alloys whose improvement in both machinability and corrosion resistance has been intended but also the first to fourth invention alloys and the fifth to ninth alloys in which nothing particular was done to improve corrosion resistance were both equal to the conventional alloy No. 13005, an aluminum bronze containing no zinc, in stress corrosion cracking resistance. Those alloys were superior in stress corrosion cracking resistance to the conventional naval brass alloy No. 13006, the best in corrosion resistance of all the expanded copper alloys under the JIS designations. In addition, oxidation tests were carried out to study the high-temperature oxidation resistance of the fifth to eighth alloys in comparison with the conventional alloys. Test pieces in the shape of a round bar with the surface cut to a outside diameter of 14 mm and the length cut to 30 mm were prepared from each of the following extruded materials: No. 8001 to No. 8008, No. 9001 to No. 9006, No. 10001 to No. 10008, No. 11001 to No. 11011 and No. 13001 to No. 13006. Each test piece was then weighed to measure the weight before oxidation. After that, the test piece was placed in a porcelain crucible and held in an electric furnace maintained at 500°C. At the passage of 100 hours, the test piece was taken out of the electric furnace and was weighed to measure the weight after oxidation. From the measurements before and after oxidation was calculated the increase in weight by oxidation. It is understood that the increase by oxidation is the amount, mg, of increase in weight by oxidation per 10 cm 2 of the surface area of the test piece and is calculated by the equation: increase in weight by oxidation, mg/10 cm 2 = (weight, mg, after oxidation - weight, mg, before oxidation) x (10 cm 2 / surface area, cm 2 , of test piece). The weight of each test piece increased after oxidation. The increase was brought about by high-temperature oxidation. Subjected to a high temperature, oxygen combines with copper, zinc and silicon to form Cu 2 O, ZnO, SiO 2 . That is, oxygen adds to the weight. It can be said, therefore, that the alloys which are smaller in weight increase by oxidation are more excellent in high-temperature oxidation resistance. The results obtained are shown in Table 28 to Table 31 and Table 33. As is evident from the test results shown in Table 23 to Table 31 and Table 33, the fifth to eighth invention alloys are equal, in regard to weight increase by oxidation, to the conventional alloy No. 13005, an aluminum bronze ranking high in resistance to high-temperature oxidation among the expanded copper alloys under the JIS designations and are far smaller than any other conventional copper alloy. Thus, it was confirmed that the fifth to eighth invention alloys are very excellent in machinability and resistance to high-temperature oxidation as well. No. alloy composition (wt%) Cu Si Pb Zn 1001 74.8 2.9 0.03 remainder 1002 74.1 2.7 0.21 remainder 1003 78.1 3.6 0.10 remainder 1004 70.6 2.1 0.36 remainder 1005 74.9 3.1 0.11 remainder 1006 69.3 2.3 0.05 remainder 1007 78.5 2.9 0.05 remainder No. alloy composition (wt%) Cu Si Pb Bi Te Se Zn 2001 73.8 2. 7 0.05 0.03 remainder 2002 69.9 2.0 0.33 0.27 remainder 2003 74.5 2.8 0.03 0. 31 remainder 2004 78.0 3.6 0.12 0.05 remainder 2005 76.2 3.2 0.05 0.33 remainder 2006 72.9 2.6 0. 24 0.06 remainder No. alloy composition (wt%) Cu Si Pb Sn Al P Zn 3001 70.8 1.9 0.23 3.2 remainder 3002 74.5 3.0 0. 05 0.4 remainder 3003 78.8 2.5 0.15 3.4 remainder 3004 74.9 2.7 0.09 1.2 remainder 3005 74.6 2.3 0.26 1.2 1.9 remainder 3006 74.8 2.8 0.18 0.03 remainder 3007 76.5 3.3 0.04 0.21 remainder 3008 73.5 2.5 0.05 1.6 0.05 remainder 3009 74.9 2.0 0.35 2.7 0.13 remainder 3010 75.2 2.9 0.23 0.8 1.4 0.04 remainder No. alloy composition (wt%) Cu Si Pb Sn AI P Bi Te Se Zn 4001 73.8 2.8 0.04 0.5 0.10 remainder 4002 74.5 2. 6 0.11 1.5 0. 04 remainder 4003 73.7 2.1 0.21 1. 2 2.2 0.03 remainder 4004 76.8 3. 2 0.05 0.03 0.31 remainder 4005 74.1 2. 6 0.07 L 4 0.04 0. 09 remainder 4006 75.5 1.9 0.32 3.2 0.15 0.16 remainder 4007 74.8 2.8 0.10 0.7 1. 2 0.05 0.05 remainder 4008 70.5 1. 9 0. 22 3.4 0.03 remainder 4009 79.1 2.7 0.15 3.4 0.05 remainder 4010 74.5 2.8 0.10 0.05 0.05 remainder 4011 77.3 3.3 0.07 0.4 0.21 0.31 remainder 4012 76.8 2.8 0.05 2.0 0.03 0.13 remainder 4013 74.5 2.6 0.18 1.4 2.1 0.21 remainder 4014 74.0 2.5 0.20 2.1 1.1 0.10 0.07 remainder 4015 72. 5 2.4 0.11 1.0 0.05 remainder 4016 76.1 2.5 0.07 2.3 0.10 remainder 4017 76.4 2.7 0.05 0.6 3.1 0.22 remainder 4018 74.0 2. 5 0.23 0.22 0. 03 remainder 4019 71.2 2.2 0.11 2.8 0.05 0.30 remainder 4020 75.3 2.7 0.22 1.4 0.03 0.05 remainder 4021 74.1 2.5 0.05 2.4 1.2 0.07 0.07 remainder No. alloy composition (wt%) Cu Si Pb Sn P Sb As Zn 5001 74.3 2.9 0.05 0.4 remainder 5002 69.8 2.1 0.31 3.1 remainder 5003 74.8 2.8 0.03 0.08 remainder 5004 78.2 3.4 0.16 0.21 remainder 5005 74.9 3.1 0.09 0.07 remainder 5006 72.2 2.4 0.25 0.13 remainder. 5007 73.5 2.5 0.18 2.2 0.04 remainder 5008 77.0 3.3 0.06 0.7 0.15 remainder 5009 76.4 3. 6 0.12 1.2 remainder 5010 71.4 2.3 0.26 2.6 0.03 remainder 5011 77.3 3.4 0.17 0.5 0.14 remainder 5012 74.8 2.8 0. 07 1.4 0.03 remainder 5013 74.5 2.7 0.05 0.03 0.12 remainder 5014 76.1 3.1 0.14 0.18 0.03 remainder 5015 73.9 2.5 0.08 0.07 0.05 remainder 5016 74.5 2.8 0.07 0.08 0.04 remainder 5017 77.3 3.1 0.12 1.5 0.13 0.05 remainder 5018 72.8 2.4 0.18 0.7 0.03 0.09 remainder 5019 74.2 2.7 0.07 0.5 0.11 0.10 remainder 5020 74.6 2.8 0.05 0.9 0.07 0.05 0.03 remainder No. alloy composition (wt%) Cu Si Pb Bi Te Se Sn P Sb As Zn 6001 70.7 2.3 0.17 0.05 2.8 remainder 6002 74.6 2.5 0.08 0.03 0.7 0.06 remainder 6003 78.0 3.7 0.05 0.34 0.4 0.05 remainder 6004 69.5 2.1 0.32 0.02 3.3 0.03 remainder 6005 76.8 2.8 0.03 0.07 0.8 0.21 0.02 remainder 6006 74.2 2.7 0.18 0.10 0.5 0.03 0.13 remainder 6007 76.1 3.2 0.12 0.05 1.7 0.12 0.02 remainder 6008 75.3 2.8 0.20 0.16 1.3 0.10 0.03 0.05 remainder 6009 77.0 3.1 0.14 0.06 0.21 remainder 6010 72.5 2.5 0.07 0.09 0.05 0.03 remainder 6011 74.7 2.9 0.10 0.32 0.14 0.10 remainder 6012 71.4 2.3 0.25 0.14 0.07 0.03 0.02 remainder 6013 74.7 3.0 0.13 0.05 0.12 remainder 6014 77.2 3.2 0.27 0.23 0.07 0.04 remainder 6015 74.0 2.8 0.07 0.03 0.03 remainder 6016 69.8 2.1 0.22 0.17 3.2 remainder 6017 73.8 2.9 0.15 0.03 1.6 0.07 remainder 6018 75.8 2.8 0.08 0.06 0.4 0.03 remainder 6019 71.2 2.3 0.15 0.07 2.5 0.07 remainder 6020 72.0 2.6 0.12 0.04 0.9 0.03 0.05 remainder No. alloy composition (wt%) Cu Si Pb Bi Te Se Sn P Sb As Zn 6021 76.8 2.9 0.20 0.30 0.8 0.17 0.03 remainder 6022 78.3 3.2 0.15 0.36 0.4 0.06 0.14 remainder 6023 73.4 2.3 0.12 0.06 2.7 0.02 0.11 0.03 remainder 6024 74.6 2.8 0.05 0.08 0.19 remainder 6025 78.5 3.7 0.22 0.25 0.23 0.03 remainder 6026 74.9 2.9 0.16 0.05 0.05 0.10 remainder 6027 73.8 2.5 0.07 0.03 0.06 0.02 0.04 remainder 6028 74.8 2.6 0.12 0.02 0.12 remainder 6029 74.2 2.8 0.37 0.10 0.11 0.02 remainder 6030 76. 3 3.2 0.08 0.05 0.07 remainder 6031 70. 8 2.4 0.11 0.05 2.6 remainder 6032 74.6 3.0 0.25 0.32 0.6 0.06 remainder 6033 75.0 2.8 0.03 0.12 0.3 0.13 remainder 6034 73.5 2.8 0.12 0.07 1.0 0.11 remainder 6035 78.0 3.3 0.07 0.03 0.5 0.16 0.02 remainder 6036 72.4 2.5 0.13 0.05 3.1 0.03 0.05 remainder 6037 78.0 2.8 0.18 0.20 1.7 0.08 0.02 remainder 6038 76.5 3.1 0.10 0.11 1.7 0. 03 0.03 0.04 remainder 6039 71.9 2.4 0.12 0.17 0.04 remainder 6040 77.0 3.5 0.03 0.35 0.23 0. 03 remainder No. alloy composition (wt%) Cu Si Pb Bi Te Se Sn P Sb As Zn 6041 74.7 2.9 0.07 0.12 0.06 0.03 remainder 6042 72.8 2.5 0.20 0.06 0.03 remainder 6043 78.0 3.7 0.33 0.15 0.02 0.10 remainder 6044 74.0 2.8 0.12 0.05 0.08 remainder 6045 76.1 3.1 0.05 0.07 0.03 0.09 0.03 remainder No. alloy composition (wt%) Cu Si Pb Sn Al P Mn Ni Zn 7001 67.0 3.8 0.04 1.6 3.2 remainder 7001a 7002 69.3 4.2 0.15 0.4 2.2 reminder 7002a 7003 63.8 2.6 0.33 2.8 0.9 remainder 7003a 7004 66.5 3.4 0.07 1.5 2.0 remainder 7004a 7005 67.2 3.6 0.10 0.9 1.8 0.9 remainder 7005a 7006 63.0 2.7 0.27 2.7 1.2 2.1 remainder 7006a 7007 68.7 3.4 0.05 1.4 1.3 0.9 remainder 7007a 7008 70.6 4.1 0.03 0.5 1.6 3.4 remainder 7008a 7009 67.8 3.6 0.12 2.6 2.1 3.3 remainder 7009a 7010 68.4 3.5 0.06 0.4 0.3 1.8 remainder 7010a No. alloy composition (wt%) Cu Si Pb Sn Al P Mn Ni Zn 7011 73.9 4.4 0.17 1.2 1.7 0.8 1.5 remainder 7011a 7012 65.5 2.9 0.20 1.5 1.0 0.12 2.3 remainder 7012a 7013 66.1 3.3 0.08 1.8 1.1 0.03 2.6 remainder 7013a 7014 70.3 3.9 0.15 1.0 1.4 0.21 1.8 1. 2 remainder 7014a 7015 66.8 3.7 0.20 2.6 0.14 2.7 remainder 7015a 7016 69.0 4.0 0.07 0.5 0.20 3.2 remainder 7016a 7017 64.5 2.9 0.19 1.8 0.05 1.5 0.8 remainder 7017a 7018 72.4 3.5 0.08 1.5 1.1 remainder 7018a 7019 69.2 3.9 0.03 0.4 3.1 remainder 7019a 7020 76.6 4.3 0.14 2.3 1.9 remainder 7020a No. alloy composition (wt%) Cu Si Pb Sn Al P Mn Ni Zn 7021 75.0 4.2 0.19 1.7 2.1 remainder 7021a 7022 72.3 3.7 0.05 1.4 1.1 0.8 remainder 7022a 7023 64.5 3.8 0.35 0.3 2.0 2.3 remainder 7023a 7024 75.8 3.9 0.05 2.7 0.04 1.0 remainder 7024a 7025 70.1 3.5 0.06 1.2 0.23 3.0 remainder 7025a 7026 67.2 2.8 0.22 1.8 0.14 2.2 0.9 remainder 7026a 7027 70.2 3.8 0.11 0.03 3.2 remainder 7027a 7028 75.9 4.4 0.03 0.20 1.1 remainder 7028a 7029 66.0 3.0 0.18 0.12 1.0 2.1 remainder 7029a No. alloy composition (wt%) Cu Si Pb AI P Z n 8001 74.5 2.9 0.16 0.2 0.05 remainder 8002 76.0 2.7 0.03 1.2 0.21 remainder 8003 76.3 3.0 0.35 0.6 0.12 remainder 8004 69.9 2.1 0.27 0.3 0.03 remainder 8005 71.5 2.3 0.12 0.8 0.10 remainder 8006 78.1 3.6 0.05 0.2 0.13 remainder 8007 77.7 3.4 0.18 1.4 0.06 remainder 8008 77.5 3.5 0.03 0.9 0.15 remainder No. alloy composition (wt%) Cu Si Pb Al P Bi Te Se Zn 9001 74.8 2.8 0.05 0.6 0.07 0.03 remainder 9002 76.6 2.9 0.12 0.9 0.03 0.32 remainder 9003 72.3 2.2 0.32 0.5 0.12 0.25 remainder 9004 77.2 3.0 0.07 1.4 0.21 0.05 remainder 9005 78.1 3.6 0.16 0.3 0.15 0.29 remainder 9006 74.5 2.6 0.05 0.6 0.08 0.07 remainder No. alloy composition (wt%) Cu Si Pb Al P Cr Ti Zn 10001 76.0 2.8 0.12 0.7 0.13 0.21 remainder 10002 75.0 3.0 0.03 0.2 0.05 0.03 remainder 10003 78.3 3.4 0.06 1.3 0.20 0.34 remainder 10004 69.6 2.1 0.25 0.8 0.03 0.17 remainder 10005 77.5 3.6 0.12 0.7 0.15 0.23 remainder 10006 71.8 2.2 0.32 1.2 0. 08 0.32 remainder 10007 74.7 2.7 0.1 0.6 0.10 0.03 remainder 10008 75.4 2.9 0.03 0.3 0.06 0.12 0.08 remainder No. alloy composition (wt%) Cu Si Pb AI Bi Te Se P Cr Ti Zn 11001 76.5 2.9 0.08 0.9 0.03 0.12 0.03 remainder 11002 70.4 2.2 0.32 0.5 0. 21 0.03 0.18 remainder 11003 78.2 3.5 0.16 1.3 0.35 0.20 0.34 remainder 11004 73.9 2.7 0.03 0.3 0.11 0.06 0.22 remainder 11005 75.8 3.0 0.06 0.6 0.08 0.11 0.10 0.07 remainder 11006 71.6 2.1 0.24 1.0 0.21 0.04 0.32 remainder 11007 73.8 2.4 0.10 1.1 0.04 0.07 0.03 remainder 11008 75.5 3.0 0.13 0.2 0.36 0.12 0.06 0.14 remainder 11009 77.7 3.2 0.03 1.4 0.17 0.23 0.23 remainder 11010 75.0 2.7 0.15 0.7 0.03 0.03 0.12 remainder 11011 72.9 2.4 0.20 0.8 0.31 0.06 0.09 0.05 remainder No. alloy composition (wt%) beat treatment Cu Si Pb Zn temperature time 12001 69.3 2.3 0.05 remainder 580°C 30min. 12002 69.3 2.3 0.05 remainder 450°C 2hr. 12003 78.5 2.9 0.05 remainder 580°C 30min. 12004 78.5 2.9 0.05 remainder 450°C 2hr. No. alloy composition (wt%) Cu Si Pb Sn Al Mn Ni Fe Zn 13001 58.8 3.1 0.2 0.2 remainder 13001a 13002 61.4 3.0 0.2 0.2 remainder 13002a 13003 59.1 2.0 0.2 0.2 remainder 13003a 13004 69.2 1.2 0.1 remainder 13004a 13005 remainder 9.8 1.1 1.2 3.9 13005a 13006 61.8 0.1 1.0 remainder 13006a No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) eloagation (%) 1001 o ○ ○ 1 1 7 1 6 0 ○ 5 3 3 3 5 ○ 1002 o ○ ○ 1 1 4 1 7 0 ○ 5 2 0 3 2 ○ 1003 o ○ ○ 1 1 9 1 4 0 Δ 5 7 5 3 6 ○ 1004 o ○ ○ 1 1 8 2 2 0 Δ 4 9 0 3 0 Δ 1005 o ○ ○ 1 1 4 1 7 0 ○ 5 4 6 3 4 ○ 1006 Δ ○ 1 2 6 2 3 0 ○ 5 0 4 3 2 Δ 1007 o ○ Δ 1 2 7 1 7 0 Δ 5 1 5 4 4 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0 °C deformability tensile strength (N/mm 2 ) elongation (%) 2001 o ○ ○ 1 1 6 1 8 0 ○ 5 1 0 3 3 ○ 2002 o ○ ○ 1 1 5 2 3 0 Δ 4 7 5 2 8 Δ 2003 o ○ ○ 1 1 5 1 6 0 Δ 5 4 0 3 2 ○ 2004 o ○ ○ 1 1 7 1 5 0 Δ 5 7 6 3 5 ○ 2005 o ○ ○ 1 1 6 1 4 0 Δ 5 4 3 3 7 ○ 2006 o ○ ○ 1 1 4 1 8 0 Δ 5 0 2 3 2 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 3001 o ○ ○ 1 2 0 3 0 ○ 5 4 2 2 3 ○ 3002 o ○ ○ 1 1 7 7 0 ○ 5 5 0 3 0 ○ 3003 o ○ ○ 1 1 9 1 1 0 Δ 5 6 5 3 4 ○ 3004 o ○ ○ 1 1 8 1 4 0 ○ 5 3 2 3 5 ○ 3005 o ○ ○ 1 1 9 5 0 Δ 5 4 7 2 7 ○ 3006 o ○ ○ 1 1 5 3 0 ○ 5 3 8 3 4 ○ 3007 o ○ ○ 1 1 7 < 5 Δ 5 6 2 3 6 ○ 3008 o ○ ○ 1 1 9 < 5 ○ 5 2 9 2 6 ○ 3009 o ○ ○ 1 1 8 < 5 Δ 5 1 8 3 0 ○ 3010 o ○ ○ 1 1 6 < 5 ○ 5 5 5 2 8 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 4001 o ○ ○ 1 1 9 7 0 ○ 5 3 5 3 0 ○ 4002 o ○ ○ 1 1 6 1 2 0 ○ 5 4 7 3 3 ○ 4003 o ○ ○ 1 1 8 6 0 Δ 5 3 9 2 6 ○ 4004 ○ ○ 1 1 3 3 0 Δ 5 5 0 3 1 ○ 4005 o ○ ○ 1 1 7 < 5 ○ 5 3 4 2 7 ○ 4006 o ○ ○ 1 1 8 < 5 Δ 5 4 2 3 0 ○ 4007 ○ ○ 1 1 6 < 5 ○ 5 6 3 3 2 ○ 4008 o ○ ○ 1 2 0 4 0 Δ 5 0 7 2 5 ○ 4009 o ○ ○ 1 1 7 1 1 0 Δ 5 7 2 3 6 ○ 4010 o ○ ○ 1 1 5 1 0 ○ 5 2 4 3 3 ○ 4011 o ○ ○ 1 1 6 <5 Δ 5 8 0 3 1 ○ 4012 o ○ ○ 1 1 4 2 0 ○ 5 7 5 3 4 ○ 4013 ○ ○ 1 1 5 5 0 Δ 5 8 8 2 8 ○ 4014 o ○ ○ 1 1 7 < 5 ○ 5 4 3 2 6 ○ 4015 o ○ ○ 1 1 7 6 0 ○ 5 0 1 2 7 ○ 4016 o ○ ○ 1 1 6 1 3 0 Δ 5 3 9 3 2 ○ 4017 o ○ ○ 1 1 8 5 0 ○ 5 7 4 3 4 ○ 4018 o ○ ○ 1 1 5 < 5 ○ 5 0 6 3 0 ○ 4019 o ○ ○ 1 1 8 < 5 ○ 5 2 3 2 8 ○ 4020 o ○ ○ 1 1 5 2 0 Δ 5 4 8 3 2 ○ 4021 o ○ ○ 1 1 8 < 5 ○ 5 5 3 2 7 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 5001 o ○ ○ 1 1 6 7 0 ○ 5 2 5 3 4 ○ 5002 o ○ ○ 1 2 0 4 0 Δ 5 0 1 2 5 ○ 5003 o ○ ○ 1 1 7 < 5 ○ 5 1 0 3 3 ○ 5004 o ○ ○ 1 1 7 < 5 Δ 5 4 7 4 2 ○ 5005 o ○ ○ 1 1 5 < 5 ○ 5 3 3 3 4 ○ 5006 o ○ ○ 1 1 6 < 5 ○ 4 7 0 3 0 Δ 5007 o ○ ○ 1 1 8 < 5 ○ 5 1 2 2 8 ○ 5008 o ○ ○ 1 1 9 < 5 Δ 5 5 8 3 6 ○ 5009 o ○ ○ 1 2 0 5 0 Δ 5 9 5 3 1 ○ 5010 o ○ ○ 1 2 1 < 5 ○ 5 1 6 2 7 ○ 5011 o ○ ○ 1 1 8 < 5 Δ 5 6 9 3 4 ○ 5012 ○ ○ 1 1 7 < 5 ○ 5 2 3 3 0 ○ 5013 o ○ ○ 1 1 6 <5 ○ 5 0 4 3 3 ○ 5014 ○ ○ 1 1 4 <5 ○ 5 3 6 3 5 ○ 5015 o ○ ○ 1 1 7 <5 ○ 4 8 8 3 1 ○ 5016 o ○ ○ 1 1 6 < 5 ○ 5 1 0 3 7 ○ 5017 o ○ ○ 1 1 8 <5 Δ 5 5 7 3 2 ○ 5018 o ○ ○ 1 1 7 <5 ○ 4 8 0 3 0 ○ 5019 o ○ ○ 1 1 7 < 5 ○ 5 1 1 3 1 ○ 5020 o ○ ○ 1 1 5 <5 ○ 5 2 8 3 0 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 6001 o ○ ○ 1 1 9 4 0 ○ 5 1 5 2 5 ○ 6002 o ○ ○ 1 1 7 < 5 ○ 4 9 6 3 5 ○ 6003 o ○ ○ 1 1 9 < 5 Δ 5 7 0 3 4 ○ 6004 o ○ ○ 1 1 8 < 5 Δ 5 0 3 2 6 ○ 6005 o ○ ○ 1 1 5 < 5 ○ 5 3 6 3 7 ○ 6006 ○ ○ 1 1 3 < 5 ○ 5 1 2 3 3 ○ 6007 o ○ ○ 1 1 7 < 5 Δ 5 5 9 2 9 ○ 6008 ○ ○ 1 1 5 < 5 Δ 5 2 7 3 1 ○ 6009 o ○ ○ 1 1 5 < 5 Δ 5 4 6 4 0 ○ 6010 o ○ ○ 1 1 6 <5 ○ 5 0 7 3 0 ○ 6011 ○ ○ 1 1 3 < 5 Δ 5 2 0 3 0 ○ 6012 o ○ ○ 1 1 5 < 5 Δ 4 8 8 2 9 Δ 6013 ○ ○ 1 1 4 < 5 ○ 5 3 1 3 2 ○ 6014 o ○ ○ 1 1 4 < 5 Δ 5 6 4 3 1 ○ 6015 o ○ ○ 1 1 5 2 0 ○ 5 2 5 3 4 ○ 6016 o ○ ○ 1 2 1 3 0 ○ 5 1 4 2 5 ○ 6017 o ○ ○ 1 1 9 <5 ○ 5 1 0 2 7 ○ 6018 o ○ ○ 1 1 6 < 5 ○ 5 2 8 3 2 ○ 6019 o ○ ○ 1 1 9 < 5 ○ 5 2 6 2 8 ○ 6020 o ○ ○ 1 1 6 < 5 ○ 5 0 9 3 0 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximm depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 6021 o ○ ○ 1 1 3 < 5 ○ 5 3 4 3 0 ○ 6022 o ○ ○ 1 1 7 < 5 ○ 5 6 2 3 4 ○ 6023 o ○ ○ 1 2 0 < 5 ○ 5 2 7 2 7 ○ 6024 o ○ ○ 1 1 6 < 5 ○ 5 1 5 3 3 ○ 6025 o ○ ○ 1 1 7 < 5 Δ 5 7 5 3 5 ○ 6026 o ○ ○ 1 1 4 < 5 ○ 5 2 4 3 2 ○ 6027 o ○ ○ 1 1 9 < 5 ○ 5 0 3 3 4 ○ 6028 o ○ ○ 1 1 7 < 5 ○ 5 1 0 3 3 ○ 6029 ○ ○ 1 1 4 < 5 Δ 5 2 2 3 0 ○ 6030 o ○ ○ 1 1 8 4 0 ○ 5 4 6 3 7 ○ 6031 o ○ ○ 1 1 9 < 5 ○ 5 2 9 2 7 ○ 6032 o ○ ○ 1 1 5 < 5 Δ 5 4 5 3 0 ○ 6033 o ○ ○ 1 1 6 < 5 ○ 5 2 1 3 4 ○ 6034 o ○ ○ 1 1 6 < 5 ○ 5 1 3 3 1 ○ 6035 o ○ ○ 1 1 8 < 5 Δ 5 6 8 3 5 ○ 6036 o ○ ○ 1 1 8 < 5 ○ 5 3 6 2 6 ○ 6037 ○ ○ 1 1 6 < 5 ○ 5 3 0 2 9 ○ 6038 o ○ ○ 1 1 7 < 5 Δ 5 5 5 3 0 ○ 6039 o ○ ○ 1 1 7 2 0 ○ 4 9 7 3 1 ○ 6040 o ○ ○ 1 1 8 < 5 Δ 5 7 4 3 5 ○ No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximm depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 6041 o ○ ○ 1 1 5 <5 ○ 5 2 0 3 4 ○ 6042 o ○ ○ 1 1 7 2 0 Δ 5 0 1 3 1 ○ 6043 o ○ ○ 1 1 8 <5 Δ 5 8 5 3 2 ○ 6044 o ○ ○ 1 1 6 <5 ○ 5 1 6 3 2 ○ 6045 o ○ ○ 1 1 6 < 5 ○ 5 3 8 3 5 ○ No. machinability machinability hot workability mechanical properties form of chippings condition of cut surface cutting force (N) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 7001 o ○ ○ 1 3 2 ○ 7 5 5 1 7 7002 o ○ ○ 1 2 7 ○ 7 7 6 1 9 7003 o ○ Δ 1 3 5 ○ 6 2 0 1 5 7004 o ○ ○ 1 3 0 ○ 7 1 4 1 8 7005 o ○ ○ 1 2 8 ○ 7 0 8 1 9 7006 o ○ ○ 1 3 0 ○ 6 8 5 1 6 7007 o ○ ○ 1 3 2 ○ 7 1 7 1 8 7008 o ○ ○ 1 3 0 ○ 8 1 1 1 8 7009 o ○ ○ 1 3 0 ○ 7 9 0 1 5 7010 o ○ ○ 1 3 1 ○ 7 0 8 1 8 7011 o ○ ○ 1 2 8 ○ 8 1 0 1 7 7012 o ○ ○ 1 2 8 ○ 6 9 4 1 7 7013 o ○ ○ 1 3 2 ○ 7 4 2 1 6 7014 o ○ ○ 1 2 8 ○ 8 0 9 1 7 7015 o ○ ○ 1 2 9 ○ 7 2 5 1 5 7016 o ○ ○ 1 2 8 ○ 7 6 5 1 8 7017 o ○ ○ 1 3 0 ○ 6 8 4 1 6 7018 o ○ ○ 1 2 8 ○ 7 1 0 2 1 7019 o ○ ○ 1 2 8 ○ 7 4 6 2 0 7020 o ○ ○ 1 2 6 ○ 8 0 2 1 9 No. machinability hot workability mechanical properties form of chippings condition of cut surface cutting force (N) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 7021 o ○ ○ 1 2 6 ○ 7 9 2 1 9 7022 o ○ ○ 1 2 8 ○ 7 6 2 2 0 7023 o ○ ○ 1 2 9 ○ 7 2 5 1 7 7024 o ○ ○ 1 2 8 ○ 7 4 4 2 1 7025 o ○ ○ 1 3 0 ○ 7 5 0 2 0 7026 Δ ○ 1 3 2 ○ 6 7 1 2 3 7027 o ○ ○ 1 2 8 ○ 7 4 0 2 3 7028 o ○ ○ 1 3 3 ○ 7 6 3 2 2 7029 Δ ○ 1 2 9 ○ 6 4 7 2 4 No. machinability corrosion resistance hot workability mechanical properties stress resistance corrosion cracking resistance form of chippings condition of cut surface cutting force (N) maximum depth of corrosion (µm) 7 0 0°C deformability tensile strength (N/mm 2 ) elongation (%) 12001 o ○ ○ 1 2 2 2 1 0 ○ 4 8 6 3 6 ○ 12002 o ○ ○ 1 1 9 2 0 0 ○ 4 9 0 3 5 ○ 12003 o ○ ○ 1 2 0 1 6 0 Δ 5 0 1 4 0 ○ 12004 o ○ ○ 1 1 9 1 6 0 Δ 5 0 5 4 1 ○ No. wear resistance weight loss by wear (mg/100000rot.) 13001a 5 0 0 13002a 6 2 0 13003a 5 2 0 13004a 4 5 0 13005a 2 5 13006a 6 0 0

Claims: A free-cutting copper alloy which comprises 69 to 79 percent, by weight, of copper; 2.0 to 4.0 percent, by weight, of silicon; 0.02 to 0.4 percent, by weight, of lead; the remaining percent, by weight, of zinc, and optionally one of: a) one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; or b) at least one element selected from 0.3 to 3.5 percent, by weight, of tin, 0.02 to 0.25 percent, by weight, of phosphorus, 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic; or c) at least one element selected from 0.3 to 3.5 percent, by weight, of tin, 0.02 to 0.25 percent, by weight, of phosphorus, 0.02 to 0.15 percent, by weight, of antimony, and 0.02 to 0.15 percent, by weight, of arsenic; and one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; or d) 0.1 to 1.5 percent, by weight, of aluminium; and 0.02 to 0.25 percent, by weight, of phosphorus; or e) 0.1 to 1.5 percent, by weight, of aluminium; 0.02 to 0.25 percent, by weight, of phosphorus; one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium, and 0.02 to 0.4 percent, by weight, of selenium; or f) 0.1 to 1.5 percent, by weight, of aluminium; 0.02 to 0.25 percent, by weight, of phosphorus; and at least one element selected from 0.02 to 0.4 percent, by weight, of chromium and 0.02 to 0.4 percent, by weight, of titanium; or g) 0.1 to 1.5 percent, by weight, of aluminium; 0.02 to 0.25 percent, by weight, of phosphorus; and at least one element selected from 0.02 to 0.4 percent, by weight, of chromium and 0.02 to 0.4 percent by weight of titanium; and one element selected from 0.02 to 0.4 percent, by weight, of bismuth, 0.02 to 0.4 percent, by weight, of tellurium and 0.02 to 0.4 percent, by weight, of selenium; and wherein the metal structure of the free-cutting copper alloy has at least one phase selected from the γ (gamma) phase and the κ (kappa) phase. A free-cutting copper alloy as defined in claim 1, which is subjected to a heat treatment of 30 minutes to 5 hours at 400 to 600°C.

Inventors: OISHI KEIICHIRO, OISHI, KEIICHIRO, OISHI, Keiichiro Sambo Copper Alloy Co., Ltd.
Applicants: SAMBO COPPER ALLOY CO LTD, SAMBO COPPER ALLOY CO., LTD
Application year: 1998
Main classification: C22C9
IPC codes: C22F1, C22C9