HARDNESS, STRENGTH, AND ELONGATION CORRELATIONS FOR SOME TITANIUM-BASE ALLOYS.

Previously published results on Al-base alloys and steels have shown that accurate prediction of yield stress and ultimate tensile stress (UTS) is possible from hardness data. The present study was undertaken to see if the relationships were also valid for Ti-base alloys. Rockwell hardness and tensile data obtained in an earlier study on three titanium-base alloys (Ti-13V-11Cr-3Al, Ti-5Al-2. 5Sn, and Ti-6Al-4V) have been augmented with Meyer, Vickers, and Knoop hardness measurements. The tensile data have been analysed to give the work-hardening coefficient n and this has been correlated with (a) the ratios of both yield stress and ultimate tensile stress to Vickers hardness; (b) the Meyer harness coefficient m; and (c) uniform elongation. The breakdown of the correlation was attributed to a different deformation mechanism, presumably micro-wtinning, occurring during hardness testing from that prevailing during tensile testing. This effect also explains, for the materials in the present study, the breakdown of both the relationship between m and n, and the relationships which involve stress/hardness ratios.