Some aspects of the structure-property relationships in 12% Cr steels

The inter-relations between solution treatment and tempering conditions and the microstructure, impact and 5500C stress-rupture properties of 12% Cr steels containing Mo, V and Nb additions have been avaluated. It was shown that reductions in impact transition temperature and increases in toughness and rupture ductility could be achieved, by suitable choice of heat treatment, but only at the expense of lowering the rupture strength. Inclusion shape control additions (Ze or rare earths) to the 12% CrMoVNb steel minimised directional anisotropy of toughness but marginally reduced the rupture strength and increased the rupture ductility. (author)