Understanding the effect of annealing temperature on the mechanical properties of thin strips made from CuNi12Zn24 alloy going through a continuous line

Abstract

Alloys of copper with nickel (5–35%) and zinc (13–45%) are known, which are called nickel silver (translated from German Neusilber – “new silver”). The alloy CuNi15Zn20 is widely used. Industry uses materials similar in properties to the alloy CuNi15Zn20, but cheaper due to the reduction in the content of nickel and copper, for example, CuNi12Zn24. Under the conditions of Kirov Non-Ferrous Metals Processing Plant (JSC “KNFMP”), there is a technical possibility to obtain products from ingots to thin strip from these alloys. To obtain thin strips 0.7–0.043 mm thick in a soft state with a uniform distribution of mechanical properties along both length and width, as well as with a high surface quality, a continuous annealing line is used. The line is usually used for annealing thin strips of copper and brass of various alloy grades. The work was carried out on the selection of temperature and speed modes of the line for heat treatment of tapes from the alloy CuNi12Zn24, not typical of the line, in order to obtain products that meet consumer requirements. The effect of annealing temperature on the change in the mechanical properties of a cold-rolled strip 0.1 mm thick made of the alloy CuNi12Zn24 was studied. The graphs of changes in the yield strength (σt), tensile strength (σb) and elongation (δ) versus annealing temperature (t) of the strip after cold rolling with a relative compression of 83% on a four-roll reversible mill 160/650×710 are obtained. The regularities are established and the dependences of the main indicators of the mechanical properties on the temperature of annealing of strips are obtained. The research results made it possible to develop a rational heat treatment regime on the continuous annealing line of JSC “KNFMP”. Application of the developed annealing regime made it possible to manufacture and supply to the European consumer an experimental batch of tapes with a cross section of 0.1×400 mm in the soft state from the alloy CuNi12Zn24 according to the standard EN 1652-97 in the amount of 1000 kg. There were no comments from the consumer about quality of the strips; currently, orders for the production of these products continue to be received at JSC “KNFMP”.