RELATIONSHIP BETWEEN WORK-HARDENING EXPONENT AND LOAD DEPENDENCE OF VICKERS HARDNESS IN COPPER

Micro-Vickers hardness measurements were conducted on pure copper under cold-worked and annealed conditions at loads ranging 0.147 to 9.8 N as well as tensile tests. Characteristics of the load dependence of the Vickers hardness (H(V) of these specimens were compared with the work-hardening exponents, n, obtained through tensile tests. There was a trend that the slope of the load dependence of the hardness was larger in copper with a smaller n. The slope, S, was a good measure for correlating with n, and n could be expressed as n = -0.293/S. The 0.2% offset stress sigma0.2 and ultimate tensile stress sigma(UTS) were estimated by using n determined from the S- n relation and the relations of Cahoon et al. and Tabor. The estimated sigma0.2 and sigma(UTs) showed good coincidence with those obtained from tensile tests.