COPPER ALLOY HAVING FINE CRYSTALLINE GRAIN AND LOW STRENGTH AND ITS PRODUCTION

PURPOSE:To obtain a Cu alloy having low strength and superior formability and excellent in stress corrosion cracking resistance, welding crack resistance, and solderability by regulating the crystalline grain size of a cold rolled sheet of a Cu-Zn alloy with a specific composition to a specific value or below by means of the final annealing and further carrying out cold rolling again, if necessary. CONSTITUTION:A hot rolled plate of a Cu alloy which has a composition consisting of, by weight, 3-25% Zn and the balance Cu or further containing 0.005-2.0%, in total, of one or >=2 elements among the group consisting of Pb, Fe, Sn, Al, Mn, Ni, P, As, Te, Cr, Co, Zr, V, Be, Cd, Si, B, In, Ti, Mg, Hf, and Ge is subjected to a repetition of cold rolling and annealing, by which an intermediate stock is prepared. This stock is annealed, cold-rolled at >=75% draft, and subjected to final annealing to undergo the regulation of crystalline grains to