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The role of retained austenite and residual stresses in rolling contact
Abstract
The effects of rolling contact on the microstructure of case carburized bearing steel have been studied experimentally, and the results examined, along with a review of the current literature and theories which are used to explain the observed phenomena. All experimental work utilized tapered rollers from 6.5 x 12 tapered roller bearings as used in the rail industry. Retained austenite, residual stress, texture and particle size at the roller surface were measured using X-ray diffraction technique. These parameters along with hardness and microstructure were also studied as a function of load-miles on new rollers, and profiles in addition these same parameters were measured as a function of depth in the case carburized layer of several samples. These characteristics were also studied as a function of the finish grinding operation, and rollers returned from long service were annealed in order to study the extent to which the changes were related to reversible processes. With all studies, whenever possible, measurements were carried out sequentially and at the same location on the rollers. Results of this research has shown that the retained austenite decreases at the surface with service mileage and load, and the residual stresses in the martensite and austenite phases become more compressive. Texture and particle size measurements along with the annealing behavior of the rollers indicated that the most significant contribution to the residual stress is from the transformation of austenite to martensite, although there is evidence that work hardening of austenite is occurring. There appears to be an early limit for most of the transformation of austenite to martensite which appears to be due to the fact that the austenite has become strengthened which then makes further transformation difficult. The behavior of the retained austenite is further classified according to three stages known as shake down, steady state and unstable.
Subject Area
Metallurgy|Materials science|Chemical engineering
Recommended Citation
Xu, Yiming, "The role of retained austenite and residual stresses in rolling contact" (1993). ETD collection for University of Nebraska-Lincoln. AAI9611077.
https://digitalcommons.unl.edu/dissertations/AAI9611077