Effect of Nickel on Strengthening and Toughening of 13% Cr Cast Stainless Steel by Quenching from (α+γ) Temperature Range

Abstract

Strengthening and toughening of a 13%Cr cast stainless steel added with Ni by heat treatment is studied. In this work, low temperature quenching treatment (L) from (α+γ) range, in the intermediate stage between usual quenching and tempering, is applied. Then, the effects of Ni content and retained austenite on the low temperature toughness are investigated. The heat treated samples are compared by V-notched Charpy impact test, dynamic fracture toughness test and static tensile test.
It is shown that the steel with higher Ni content has the better low temperature toughess, and that the L treatment improves the toughness of the 13%Cr cast steel. Improvement of the low temperature toughness due to the L treatment becomes larger in the higher Ni content steel. It is also shown that the stable and fine retained austenite improves the toughness and the ductility at low temperature. This may be due to the transformation induced plasticity of the retained austenite.