Effect of addition of rare earth metal on hot tensile properties of low carbon, low alloy martensite

Abstract

AbstractThe effects of the addition of rare earth metal (REM) on the stress relief cracking susceptibility of low alloy martensite have been examined by slow strain rate tensile tests. The partial dissolution of MnS by austenitization before quenching at temperatures as high as 1573 K promoted the intergranular decohesive mode of fracture in hot tensile tests, and the stabilization of free S atoms by the addition of REM increases ductility at temperatures between 823 and 890 K and the fracture morphology changes to that of intergranular microvoid coalescence. However, in higher temperature deformation in the range from 890 to 973 K, the addition of REM reduces ductility and increases the fraction of intergranular microvoid coalescence at the expense of the transgranular ductile fracture mode. This can be explained in terms of AlN precipitation in relation to the dispersion of fine MnS particles.