METHOD FOR SUBJECTING HIGH-ALLOY STEEL MEMBER TO GAS SOFT-NITRIDING

摘要

PURPOSE:To improve remarkably the bending fatigue strength of a high-alloy steel member by subjecting the member to gas soft-nitriding at a specified temp. in an atmosphere prepd. by adding a specified amount of air to a gaseous mixture of an endothermic gas with gaseous ammonia. CONSTITUTION:A high-alloy steel member cold worked or aged at a low temp. is subjected to gas soft-nitriding at 400-550 deg.C in an atmosphere prepd. by adding 0.1-4.0vol% air to a gaseous mixture of an endothermic gas with gaseous ammonia. By this method, a strengthening effect at low temp. produced by the cold working or aging before the gas soft-nitriding is not reduced and is combined with an effect produced by the gas soft-nitriding, so the bending fatigue strength of the high-alloy steel member can be improved remarkably.