Effects of W on Mechanical Properties and Microstructure of a Highstrength 9% Cr Heat Resisting Steel

Abstract

The change of mechanical properties and microstructure has been investigated by substituting W for a part of Mo in a 9% chromium heat-resisting steel.
Substituting W for a part of Mo has little effect on tensile and impact properties at room temperature as well as creep rupture strength at under 600°C, but shows benefitial effects on long-term creep rupture strength at above 650°C. This is related to the fact that the substitution reduces the coarsening tendecy of precipitates and inhibits the formation of M₆C which is considered detrimental to elevated temperature strength.