Copper alloy sheet, and method of producing copper alloy sheet

A method of producing the copper alloy sheet, the method comprising:

• a hot rolling process, a cold rolling process, a recrystallization heat treatment process, and a finish cold rolling process in this order,
• wherein a hot rolling initiation temperature of the hot rolling process is 800° C. to 940° C., and a cooling rate of a 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, and
• 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 a cold working rate at the cold rolling process is set as RE (%), 550≦Tmax≦790, 0.04≦tm≦2, and 460≦{Tmax−40×tm−1/2−50×(1−RE/100)1/2}≦580.

A method of producing the copper alloy sheet, the method comprising:

• a hot rolling process, a cold rolling process, a recrystallization heat treatment process, a finish cold rolling process, and a recovery heat treatment process in this order,
• wherein a hot rolling initiation temperature of the hot rolling process is 800° C. to 940° C., and a cooling rate of a 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 a cold working rate at the cold rolling process is set as RE (%), 550≦Tmax≦790, 0.04≦tm≦2, and 460≦{Tmax−40×tm−1/2−50×(1−RE/100)1/2}≦580,
• the recovery 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, and
• in the recovery heat treatment process, when the highest arrival temperature of the copper alloy material is set as Tmax2 (° 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 tm2 (min), and a cold working rate at the finish cold rolling process is set as RE2(%), 160≦Tmax2≦650, 0.02≦tm2≦200, and 100≦{Tmax2−40×tm2−1/2−50×(1−RE2/100)1/2}≦360.