PROCESS FOR THE MANUFACTURE OF A CASE HARDENED OR CARBONITRIDED STEEL MECHANICAL PART AND STEEL FOR THE MANUFACTURE OF THE SAID PART

摘要

A method of manufacturing a steel mechanical part in which a steel part blank is manufactured and a high temperature carburizing or carbonitriding treatment is carried out on at least a portion of the surface of the blank of the piece, the chemical composition of the steel of which the piece comprises comprising, by weight: 0.15% C 0.35%; 0% If 0.6%; 0% Mn + Cr + Ni + Mo.ltoreq.5%; 0% .ltoreq.Al.ltoreq.0.1%; 0% .ltoreq.Cu.ltoreq.0.5%; 0% .ltoreq.Ti.ltoreq.0.05%; 0.004% .times.N 0.02%; 0% S 0.15%; P 0.03%; optionally, up to 0.02% tellurium, up to 0.04% selenium, up to 0.07% lead, up to 0.005% calcium, the remainder being iron and impurities resulting from development; the chemical composition being adjusted so that the steel curve is such that: 31 HRC.ltoreq.J25.ltoreq.40 HRC; the average values J3n, J11m and J25m of five JOMINY tests being such that | J11m-J3m .times. 14/22 - J25m .times. 8 / 22| .ltoreq.2,5 HRC and J3m-J15m .ltoreq. 9 HRC. Carburizing or carbonitriding steel to make this part. Figure for the abstract: none