Rolling-Contact Fatigue Studies With Four Tool Steels and a Crystallized Glass Ceramic

The rolling-contact fatigue properties of crystallized glass ceramic balls together with AISI M-1, AISI M-50, Halmo, and WB-49 alloy steel balls tempered to various hardness levels were determined in the NASA spin rig and in the five-ball fatigue tester. A continuous increase in fatigue life and load capacity for each steel was observed with increased ball hardness. These results correlate with resistance to plastic deformation as measured with spherical specimens in rolling contact but do not correlate with elastic limit and yield strength measured for bar specimens. These bar specimens showed optimum values at intermediate hardness levels. Extremely low scatter in fatigue life for the ceramic balls indicate that the degree of structural homogeneity may be an important factor in life scatter of bearing materials.