Wrought copper-zinc alloy, semi-finished product formed of a wrought copper-zinc alloy and method for producing a semi-finished product of this type

Abstract

Wrought copper-zinc alloy for producing a semi-finished product with composition in wt. %: Cu: 58.0 to 66.0%, Si: 0.15 to 1,2%, P: 0.20 to 0.38%, Sn: up to 0.5%, Al: up to 0.05%, Fe: up to 0.3%, Ni: up to 0.3%, Pb: up to 0.25%, Bi: up to 0.1%, Te, Se, In: 0.1%, B: up to 0.01%, the rest Zn and impurities. The alloy has globular a-phase, B-phase and phosphide particles. The proportion of B-phase in the sum of α-phase and β-phase is 20 vol. % and max. 60 vol. %. In an area of 21000 μm 2 are 50 to 700 phosphide particles with an equivalent diameter of 0.5 to 1 μm, 10 to 300 phosphide particles with an equivalent diameter of 1 to 2 μm, and 3 to 45 phosphide particles with an equivalent diameter of 2 to 5 μm.

1 . A wrought copper-zinc alloy for production of a semifinished product in wire, tube or bar form, having the following composition in % by weight:
 Cu: 58.0% to 66.0%,   Si: 0.15% to 1.2%,   P: 0.20% to 0.38%,   Sn: optionally up to 0.5%,   Al: optionally up to 0.05%,   Fe: optionally up to 0.3%,   Ni: optionally up to 0.3%,   Pb: optionally up to 0.25%,   Bi: optionally up to 0.1%,   Te, Se, In: each optionally up to 0.1%,   B: optionally up to 0.01%,   balance: Zn and unavoidable impurities,   where the proportion of unavoidable impurities is less than 0.20% by weight,   where the alloy has a microstructure composed of globular a phase, β phase and phosphide particles, and the proportion of the β phase in the sum total of α phase and β phase is at least 20% by volume and at most 60% by volume,   where Si is present both in the α phase and in the β phase,   where, in an area of 21 000 μm 2 , there are 50 to 700 phosphide particles having an equivalent diameter of 0.5 to 1 μm, 10 to 300 phosphide particles having an equivalent diameter of 1 to 2 μm, and 3 to 45 phosphide particles having an equivalent diameter of 2 to 5 μm, and where the proportion of the β phase and the proportions of Si, P and Pb are chosen such that the alloy meets the condition   107 378−2,25255·[beta]−64.1438·[Si]−115.18·[P]−30.7071·[Pb]+0.017965·[beta]·[beta]+24.6217·[Si]·[Si]+66.7257·[P]·[P]+0.542512·[beta]·[Si]+1.36208·[beta]·[P]+43.4012·[Si]·[P]<37   where [beta] denotes the proportion of the β phase in % by volume, [Si] the proportion of silicon in % by weight, [P] the proportion of phosphorus in % by weight, and [Pb] the proportion of lead in % by weight.   
     
     
         2 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the Pb content is at least 0.02% by weight. 
     
     
         3 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the ratio of the proportions by weight of P and the sum total of Fe and Ni is more than 2.0. 
     
     
         4 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the proportions of Fe and Ni add up to not more than 0.1% by weight. 
     
     
         5 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the P content is at least 0.26% by weight and at most 0.33% by weight. 
     
     
         6 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein Si content is not more than 0.35% by weight. 
     
     
         7 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the Si content is at least 0.25% by weight. 
     
     
         8 . The wrought copper-zinc alloy as claimed in  claim 6 , wherein the Cu content is at least 60.0% by weight and not more than 61.5% by weight. 
     
     
         9 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the Si content is at least 0.50% by weight and at most 1.0% by weight. 
     
     
         10 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the alloy has a hardness of at least 170 HV10. 
     
     
         11 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the alloy has a tensile strength R m  of at least 520 MPa. 
     
     
         12 . The wrought copper-zinc alloy as claimed in  claim 1 , wherein the alloy has an α grain size of not more than 21 μm. 
     
     
         13 . The wrought copper-zinc alloy as claimed in  claim 6 , wherein the alloy has an electrical conductivity of at least 12 MS/m. 
     
     
         14 . A semifinished product in wire, pipe or bar form, made from a wrought copper-zinc alloy as claimed  claim 1 . 
     
     
         15 . A component produced by machining and optional further processing steps from a semifinished product as claimed in  claim 14 . 
     
     
         16 . A process for producing a semifinished product in wire, pipe or bar form, wherein the process comprises the following steps:
 a) melting a copper alloy having a composition as claimed in  claim 1 ,   b) continuously casting a tubular or bolt-shaped cast format with a water-cooled mold,   c) hot pressing the cast format at a temperature of 620 to 700° C. with subsequent cooling at a cooling rate of 30 to 60° C. per minute within a temperature range from 550 to 350° C.,   d) optionally, heat treatment within a temperature range from 525 to 625° C. for 1 to 5 hours with subsequent cooling at a cooling rate of 20 to 40° C. per minute within a temperature range from 500 to 350° C.,   e) optionally, cold forming.