Effect of vanadium and titanium on mechanical properties of chromium-tungsten steels

Abstract

Increasing the vanadium content from 0.1 to 0.50% in a 2.25Cr-2W-0.1C steel (all concentrations are in wt%) increased the yield stress 20% and resulted in a higher ductile-brittle transition temperature (DBTT). When vanadium was increased to 0.5%, a further slight increase in strength occurred with a large increase in DBTT. Thus, optimum strength and impact toughness is achieved at an intermediate vanadium concentration. With the addition of 0.02% Ti to 2.25Cr-0.25V-0.1C, 2.25Cr-2W-0.1C, and 2.25Cr-2W-0.25V-0.1C steels, yield stress decreased 10 to 30%. An increase in impact toughness accompanied the strength loss. The toughness may have been affected by a decrease in the prior austenite grain size. There was little difference in the DBTT of the Ti-modified steels tempered at 700 or 750°C. The use of a Ti-modified steel tempered at 700°C might offset the strength advantage of steels without titanium, which have to be tempered at the higher temperature.