Low-carbon, low-chromium carburizing high speed steels

摘要

High speed steel (HSS) compositions having less C and Cr contents than standard grades of HSS to permit carburization using conventional techniques. The alloys contain less than 0.40 wt. % C and less than 2% Cr. The low Cr content is a critical factor in enhancing the ease of carburizing the present steels. The resulting HSS compositions possess high hardness and fracture resistance. More particularly, the steels include, in % by weight: 0-0.4% C; 0.5-1.5% Cr; 1.5-3.5% Ni; 0.1-0.6% M; 0.15-0.65% Si; 0.03 max % P; 0.03 max % S; one or more members selected from the group consisting of 4.0-15.3% Mo; 1.0-5.7% V; up to 13% Co and up to 28% W, and wherein the aggregate amount of %Cr%Mo%V%W%Co is between 7.5-35% and balance essentially Fe and incidental impurities. A method for treating the above alloy includes the steps of carburizing at about 960 C. followed by quenching, preheating to about 870 C. followed by austenitizing at 1125 C.-1225 C., quenching, and tempering twice at temperatures up to 550 C. followed by air cooling.