Method of producing copper alloy sheet for vehicle or electric/electronic component having excellent strength, electrical conductivity, and bendability, and copper alloy sheet produced thereby

1:

• A method for producing a copper alloy sheet for an automobile component and an electrical and electronic component,
• wherein the copper alloy sheet consists of 1.5 to 3.4 wt % nickel (Ni), 0.1 to 1.5 wt % cobalt (Co), 0.3 to 1.2 wt % silicon (Si), 0.1 to 0.8 wt % tin (Sn), 0.01 to 0.45 wt % chromium (Cr), the balance copper (Cu), and unavoidable impurities of a total content of 0.4 wt % or smaller, wherein the unavoidable impurities include at least one selected from a group consisting of Mg, Al, P, Ca, Ti, V, Zn, Fe, Zr and Mn,
• wherein the method comprises:
• melting and casting 1.5 to 3.4 wt % nickel (Ni), 0.1 to 1.5 wt % cobalt (Co), 0.3 to 1.2 wt % silicon (Si), 0.1 to 0.8 wt % tin (Sn), 0.01 to 0.45 wt % chromium (Cr), the balance copper (Cu), and the unavoidable impurities of a total content of 0.4 wt % or smaller, thereby obtaining an ingot;
• hot-rolling the obtained ingot in a temperature range of 900° C. to 1040° C.;
• performing first cold-rolling of the sheet obtained in the previous step at a reduction ratio of 50% or greater;
• performing intermediate heat treatment of the sheet obtained in the previous step in a temperature range of 400° C. to 800° C. for 1 to 300 minutes;
• performing second cold-rolling of the sheet obtained in the previous step at a reduction ratio of 70% to 90%;
• solution-treating the sheet obtained in the previous step in a temperature range of 820° C. to 1000° C. for 20 to 300 seconds;
• performing finishing cold-rolling of the sheet obtained in the previous step at a reduction ratio of 10% to 50%;
• and
• performing a two-step aging treatment in which the product obtained in the previous step is subjected to aging treatment in a temperature range of 440° C. to 600° C. for 5 minutes to 300 minutes, followed by aging treatment in a temperature range of 350° C. to 440° C. for 1 hour to 30 hours.