Thermomechanical Working of Electroslag Melted M-50 Bearing Steel.

摘要

A number of electroslag (ESR) melting procedures were investigated with the objective of establishing the thermomechanical working (ausforming) characteristics of M-50 bearing steel produced by this method. The ESR processes evaluated were: Electroslag remelted - Air melted electrode, Electroslag remelted - Vacuum induction melted electrode, Powder-strip electroslag melting, Double electroslag remelted - Vacuum induction melted electrode, and Continuous electroslag melting. Rolling contact fatigue testing, heat treat studies and other metallurgical tests were performed on most of these materials utilizing standard heat treat procedures as well as a thermo-mechanical process. In the latter case, high energy rate foward extrusion using Controlled Energy Flow Forming (CEFF) equipment was employed. Test results showed the ESR M-50 hardened by standard heat treat procedures to have comparable rolling contact fatigue lives to vacuum melted M-50. It was further indicated that ESR M-50 has improved workability over vacuum melted material in the ausforming temperature range. Thermo-mechanical processing however appeared to have little or no effect in improving the rolling contact fatigue life of ESR M-50. This is believed to be due mainly to the massive residual eutectic carbides observed in all of the ESR materials. This condition appears to be more severe and prevalent in the ESR M-50 than in material produced by vacuum melting. (Author)