Further Compositional Effects on the Temper Embrittlement of 2 1/4 Cr-1 Mo Steels

Abstract

As an extension of a previous study (reference [1]), the effects of a 0.3 pct nickel content, of tin in combination with several other elements, and of a 0.1 pct vs a 0.2 pct carbon content, were examined in 2 1/4 Cr-1 Mo steel having a bainitic microstructure, a hardness of Rc 15, and a grain size in the range ASTM no. 5 to 7. The main effect of the nickel was reduction in the FATT of steels in the unembrittled condition. The only deleterious effect was a small contribution to temper embrittlement in the steel containing high manganese and silicon concentrations. Tin was found not to be an embrittling element in this class of steel in the sense that it segregates and lowers intergranular cohesion. However, it strongly promotes phosphorus-induced temper embrittlement, apparently in a manner similar to silicon. A modified type of plot relating composition to temper embrittlement susceptibility is proposed. It was found that the 0.1 pct and 0.2 pct carbon steels had equivalent temper embrittlement behavior when the hardness and grain size were held constant.