PRELIMINARY METALLOGRAPHIC STUDIES OF BALL FATIGUE UNDER ROLLING-CONTACT CONDITIONS

摘要

This initial metallographic investigation included macroscopic and microscopic studies of representative samples from each lot of balls tested in the rolling-contact fatigue .spin rig. SAE 52100 standard bearing steel and AISI M-l tool steel balls were investigated at both room temperature (80℉) and at 200° to 250℉.nIn this investigation fiber direction, inclusions, and chemical segre¬gation were found to contribute much toward fatigue failures and life scatter.nStructures in the maximum-shear-stress area were stable at room tem-perature, but unstable when tested at 200° or 250℉. Thus, both SAE 52100 and AISI M-i steel were sensitive to a small temperature increase.