Patent ID: 8992706
Filing Date: 2015-03-31
Classification: B21B,C22C,C22F,H01B

Abstract:
1. A method of producing a copper alloy sheet, the method comprising: in this order, subjecting an ingot to a hot rolling process to obtain a copper alloy material; subjecting the copper alloy material to a cold rolling process; subjecting the copper alloy material to a recrystallization heat treatment process; and subjecting the copper alloy material to a finish cold rolling process to provide a copper alloy sheet, wherein a hot rolling initiation temperature of the hot rolling process is 800° C. to 940° C., and a cooling rate of the copper alloy material in a temperature region from a temperature after final rolling or 650° C. to 350° C. is 1° C./second or more, a cold working rate in the cold rolling process is 55% or more, the recrystallization heat treatment process includes a heating step of heating the copper alloy material to a predetermined temperature, a retention step of retaining the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and a cooling step of cooling down the copper alloy material to a predetermined temperature after the retention step, in the recrystallization heat treatment process, when the highest arrival temperature of the copper alloy material is set as Tmax (° C.), a retention time in a temperature range from a temperature lower than the highest arrival temperature of the copper alloy material by 50° C. to the highest arrival temperature is set as tm (min), and the cold working rate at the cold rolling process is set as RE (%), 550≦Tmax≦790, 0.04≦tm≦2, and 460≦{Tmax−40×tm an average grain size of the copper alloy material before the finish cold rolling process is 2.0 μm to 8.0 μm, circular or elliptical precipitates are present in the copper alloy material before the finish cold rolling process, and an average particle size of the precipitates is 4.0 nm to 25.0 nm, or a percentage of the number of precipitates having a particle size of 4.0 nm to 25.0 nm makes up 70% or more of the precipitates, the copper alloy sheet contains 4.5% by mass to 12.0% by mass of Zn, 0.40% by mass to 0.90% by mass of Sn, 0.01% by mass to 0.08% by mass of P, and either one or both of 0.005% by mass to 0.08% by mass of Co and 0.03% by mass to 0.85% by mass of Ni, with the remainder being Cu and unavoidable impurities, and [Zn], [Sn], [P], [Co], and [Ni] satisfy a relationship of 11≦[Zn]+7×[Sn]+15×[P]+12×[Co]+4.5×[Ni]≦17, wherein [Zn], [Sn], [P], [Co], and [Ni] represent the contents % by mass of Zn, Sn, P, Co, and Ni, respectively.