Effects of alloying elements on solidification process and hardenability of high carbon high speed steel type alloy

摘要

The effects of alloying elements on the solidification process of high carbon high speed steel type alloy were investigated by using a series of hypo-eutectic alloys of Fe-2 % C-5 % Cr-5 % Mo-5.5 % V-0/5 % W-0/5 % Co-0/5 % Ni and a hyper-eutecticFe-2.3 % C-5 % Cr-5 % Mo-9 % V-5 % W-5 % Co alloy. The solidification process of each alloy was investigated by thermal analysis and quenching experiments. In each hypo-eutectic alloy, crystallization proceeds in the order of primaryγ, γ + MC eutectic,γ + M{sub}2C eutectic, while the primary MC instead of r crystallizes in the hyper-eutectic alloy. The amount and distribution of each carbide are explained with the phase diagram and the redistribution of alloying elements during solidification. Thehardness of quenched alloy was maximum at an austenitizing temperature between 1273 K and 1373 K since the hardness depends on both the amount and hardness of martensite, that is the carbon content of austenite. Each alloy was found to exhibit a temperhardening, Co in particular enhanced the hardness when the alloy was tempered at around 823 K.