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STRUCTURAL STUDIES OF BEARING STEEL UNDERGOING CYCLIC STRESSING.
Progress rept. no. 3, 1 May-31 Dec 65,
SKF INDUSTRIES INC KING OF PRUSSIA PA ENGINEERING AND RESEARCH CENTER
Pagination or Media Count:
A number of typical spall characteristics were revealed by low and high power light microscope examinations of multiple sections made through the spalled area of deep groove ball bearing inner rings taken from 52100 steel bearings that failed in the course of laboratory endurance tests. Deformation bands were found to play a significant role in the propagation of spalls and an idealized model for spall propagation in the presence of deformation bands is proposed. There is evidence that even very limited amounts of deformation bands have an influence on spall propagation. Extensive deformation bands were seen lying at anomalous depths immediately below the surface in close proximity to surface imperfections. These surface imperfections furrows are microscratches introduced during the final surface grinding operation and are not considered unusual for this type of surface finish. The appearance of structural alteration close to the surface testifies to the stress raising ability of even small surface imperfections and in cases where furrows were present, the spalls appear to have initiated at them. Author
APPROVED FOR PUBLIC RELEASE