DE1927160C3 - Process to improve the deformability of semi-finished products made of hardenable copper-nickel-silicon alloys - Google Patents

Description

Wärmeaushärtungsfähige Kupfeilegierungen with _aJ nickel and silicon as the target components to be used in the deformed and optionally annealed and hardened state, are already known. According to * DIN 17666, November 1964 edition, these alloys consist of 1.1 to 4.5 percent by weight nickel and 0.4 to 1.3 percent by weight silicon, the remainder being copper. In many cases, iron is also present as a further admixture in amounts of up to a few tenths of a percent by weight.

It has been shown, however, that in these known alloys, as a result of the artificial hardening process a reduction of the hernia constriction, which in turn a characteristic feature of the Deformability occurs. The reduction in the constriction of the fracture occurs particularly in Appearance when artificial hardening is preceded by no or only a relatively small amount of cold deformation. The artificially hardened copper-nickel-silicon alloys go through depending on the Degree of previous cold deformation a ductility minimum, which with a low content of Nickel and silicon are hardly present, but with increasing alloy content it becomes more and more pronounced is published ("Low-alloy copper alloys" from the German Copper Institute, Berlin 1966, Pp. 202 to 204, p. 297). So shows z. B. a copper-nickel-silicon alloy, consisting of

1.9 weight percent nickel

0.4 weight percent silicon

Remainder copper

after cold deformation from the solution-annealed condition with subsequent artificial aging, the consists of an annealing of 1.5 h at 475 ° C, the following mechanical values:

Degree of cold deformation 0%

Yield strength 46 kp / mm ²

Tensile strength 58 kp / mm ²

Constriction of the fracture 26%

Cold deformation ^{degree 30% 6j}

Yield strength 59 kp / mm ²

Tensile strength 65 kp / mm ²

Neck area 35%

With a degree of cold deformation of z. B. only 20% muli one with the nickel and present here Silicon concentrations according to previous experience (see literature cited above) expect an even lower fracture necking than nadi 0 or 30% cold deformation.

According to the invention, this problem is solved by a method in which the Deformability while maintaining the strength of semi-finished products made of hardenable copper-nickel-silicon alloys, which are quenched after hot forming and solution annealing, not or only cold-formed up to 30% reduction in cross-section and then hardened, from a copper alloy with 1 to 5 percent by weight nickel, 0.3 Up to 1.5 percent by weight silicon, the remainder copper with the usual impurities, for example iron. Zinc and tin are assumed and this alloy still contains 0.04 to 2 percent by weight of aluminum can be added.

Similar improvements in the ductility of semi-finished products made from hardenable copper Nickel-silicon alloys, such as the alloying of aluminum, can also be achieved through alloying of chromium (German Auslegeschriit 12 78 110). The use of aluminum as an additive but represents a considerable technical advance compared to the use of chromium! Due to its high melting point and the wide miscibility gap, chromium can be found in the copper-chromium system difficult to alloy into the copper. In general, the melts are therefore preheated the addition of the chromium or the copper-chromium master alloys. Such a measure brings increased Melting times, increased energy costs and the risk of increased hydrogen absorption by the melt with himself. In addition, copper alloy drums containing chromium present increased difficulties with Shed. Chromium oxide inclusions easily occur. Aluminum, on the other hand, can be used Alloy copper alloy melts without any effort. It makes it easier in contrast to the chrome potting, in that it protects the pouring stream from the uptake of oxygen. Also, is aluminum considerably cheaper than chrome.

In the method according to the invention, it is expedient to proceed in such a way that initially nickel and silicon in the form of master alloys are added to a deoxidized copper melt and thereafter Aluminum either in elemental form or in the form of a master alloy in the melt is alloyed. After pouring the melt and then kneading it into semi-finished products there is a quenching 'on the solution annealing temperature. The solution annealing temperature should be above the solubility limit can be selected, around 800 ° C. The quenching can either be immediate after the kneading treatment, for example a pressing or after a Intermediate cooling and heating to the aforementioned solution annealing temperature. To the deterrence, what should be done in water, if possible, is followed by artificial hardening. The material becomes too for this purpose heated to temperatures between 300 and 500 ° C and then, left to itself, on Air cooled. However, cold deformation can also precede the artificial hardening. If an aluminum-free material does this

3 4

Deformation and bath treatment process un- cold deformation degree 0%

is subject to and cold deformation only up to a yield point of 46 kp / mm ²

60% shows a reduced Brudiein tensile strength of 58 kp / mm ²

constriction compared to the semi-finished product from the invention- breakage constriction 45%

appropriately manufactured semi-finished alloys. 5 Degree of cold deformation 30 ¹ Vo

The following examples show that the yield strength is 56 kp / mm ²

which way the aluminum-containing tensile strength produced in this way is 63 kp / mm ²

Alloys are superior to the aluminum-free ones. Reduction of the fracture 53%

An aluminum-containing copper-nickel-silicon alloy

tion, consisting of io You can see the considerable increase in ductility

1.9 weight percent nickel ^{effect of the} aluminum additive in the cold forming

0.4 percent by weight silicon grades of 0 and 30%. The strength values

0.1 weight percent aluminum! ^e S ^{en in dl (} ? ^{en 1} ^ ", ^Fal ! ^{en m} f \ ^od f ^nur ^ ^tnn " -

Remainder KuDfer ^ ¹ S among those of the aluminum-free alloy.

15 The method according to the invention takes place with demonstration after cold deformation from the solution part, especially in the area of application in which Annealed condition with subsequent artificial aging - the aluminum-free copper-nickel-silicon work, those affected in an annealing of 1.5 hours at 475 ° C by the artificial hardening a special one the following mechanical values: experienced a sharp decrease in ductility.

Claims (1)

Claim: Method for improving the formability while maintaining the strength of semi-finished aushäribaren copper-nickel-silicon alloys, not diie after hot forming and solution annealing at- ^ t scares, or only to 30 ¹ Vo decrease in cross section cold-formed and hardened subsequently excluded, characterized characterized in that a copper alloy with 1 to 5 percent by weight nickel, 0.3 to 1.5 percent by weight silicon, the remainder copper with the usual impurities, for example iron, zinc and »5 tin, is used and this alloy still 0.04 to 2 Weight percent aluminum can be added.