SUPERPLASTIC BEHAVIOUR OF LOW-ALLOY TOOL STEELS

Abstract

From tensile and upsetting tests performed at various strain rates and temperatures we have established that the W9 tool steel, which is alloyed with a little Cr and W, shows superplastic behaviour at 710 cC, with a strain rate in the order of e = 10-4 s -1, and this state can be described by a sensitivity to strain rate exponent around m=O.5 (maximum m=0.52). The yield strength in this case is 60--100 MPa. On the basis of these data we can assume that the W9 steel is suitable for being processed by superplastic formation technology.