Rolling Contact Fatigue Testing of Thermomechanically Processed M-50 Steel

摘要

The influence on rolling contact fatigue behavior of thermomechanical processing (TMP) to refine grain and soluble carbide size was studied in this work on VIM-VAR M-50 steel. Material was processed (austenitized and warm-rolled) following the procedures developed by Larson, with subsequent austenitization times and temperature (for final hardening) based on Bres' data. Rolling contact fatigue testing indicates virtual equivalence of the as-received (spheroidize-annealed) and TMP specimens evaluated, with the TMP material clearly no better than the as-received condition in terms of fatigue life. This is believed to be the result of one or both of the following: (a) austenitization (hardening) of TMP material at too long a holding time, with a microstructural equalization occuring between conditions; and (b) voids existing at the ends of insoluble carbides in both as-received and TMP material, which act as possible sites for crack initiation in the matrix.