Role of Inclusions, Surface Roughness and Operating Conditions on Rolling Contact Fatigue

Abstract

Tests have been performed on a two-disk machine in order to evaluate the role of inclusions, surface roughness and operating conditions on rolling contact fatigue of AISI 52100 and M50 bearing steels. Important parameters-such as nature and location of inclusions, small and large wavelengths of surface roughness, normal loading or sliding conditions-on crack initiation and propagation stages have been identified. The operating conditions have been selected to encompass typical jet engine applications. Tests have been carried out up to 4.2 GPa, for two different surface finishes. Surface distress and sub-surface damage which could result in catastrophic failure have been observed. Indeed, surface initiated deep spalling (observed at 3.5 GPa for unpolished surfaces and under rolling plus sliding conditions) as well as sub-surface initiated deep spalling (at 4.2 GPa for polished specimens) have been observed. Sub-surface micro-cracks were detected early and followed during some interrupted tests by the means of an ultrasonic echographic device. Results of our experiments are analyzed and discussed in relation to the rolling contact fatigue theories.

Quantitative distribution analysis of alumina inclusion particles in ferritic stainless steels by using laser‐induced breakdown optical emission spectrometry

“…For instance, non-metallic inclusion particles such as aluminum oxide generally decrease the fatigue strength of structural steels, and sometimes leave any scratches and creases on the surface of the final product. [3,4] Therefore, it is necessary to develop a rapid analytical method for quantification of non-metallic inclusions so that they can be on-site/ in-line controlled in the manufacturing process of steel products. [5] Conventional analytical methods for estimating inclusion particles in steel can be classified into two groups: a chemical method and a direct observation method.…”

Nonuniformity of morphology and mechanical properties on the surface of single crystal superalloy subjected to laser shock peening

“…The effect of work hardening brings the increasing of the strength and hardness and the decreasing of ductility and toughness of metal materials [8]. It is generally considered that cracks usually originate from the brittle phases due to their low toughness in the process of service [9], and mechanical properties heterogeneity is bound to cause the stress concentration phenomenon when the workpiece is under the action of external force [10,11]. On the basis of that, if an inhomogeneity of mechanical properties is induced by the transformation of surface morphological structures under laser shock, the service performance of the workpieces strengthened by LSP will be affected strongly by the nonuniformity of mechanical properties.…”

Multiscale modeling and simulation of rolling contact fatigue

“…When the cracks reach a critical length or depth, they branch up towards the free surface. Then, a piece of surface material is removed, and a pit is formed [3], As shown in Fig. 1.5.…”

“…2.6, an asymmetry in the density profiles is notices due to the normal motion only of the upper boundary layer while the lower boundary layer is fixed in the z direction. As it is mentioned before, the united atoms include CH 3 and CH 2 which have corresponding atom mass and the volume confined between the walls to calculate the average density. Fig.…”