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 mechanical steel part wherein a steel is produced workpiece blank and performs processing of cémentati one or carbonitriding high temperature of at least a portion of the surface of the blank of the part, the chemical composition of the steel making up the piece comprising, by weight: 0.15% ~ C ~ 0.35%; 0% ~ If ~ 0.6%; 0% ~ Mn + Cr + Mo + N i ~ 5%; 0% ~ Al ~ 0.1%; 0 ~% ~ 0.5% Cu; 0% ~ Ti ~ 0.05%; 0.004% ~ 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 Jominy curve of the steel is such that the: ~ J3 ~ 45 HRC 50 HRC; HRC 39 ~ J11 ~ 47 HRC; HRC 31 ~ J25 ~ 40 HRC; the average values ​​J3m, J11m and J25m of five Jominy tests are such that: ~ J11m - J3m x 14/22 - J25m x 8/22 ~ 2.5 HRC and J3m - J15m ~ 9 HRC. Steel carburizing or carbonitriding to make this part.