Influence of Residual Stress and Temperature on the Cyclic Hardening Response of M50 High-Strength Bearing Steel Subjected to Rolling Contact Fatigue
01 Apr 2016-Journal of Engineering Materials and Technology-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 138, Iss: 2, pp 021003
TL;DR: In this article, microstructural and mechanical characterization of a through-hardened M50 bearing steel is presented to compare and contrast their performances under rolling contact fatigue (RCF) loading.
Abstract: Microstructural and mechanical characterization investigations on three variants of a through-hardened M50 bearing steel are presented to compare and contrast their performances under rolling contact fatigue (RCF) loading. Baseline (BL) variant of M50 steel bearing balls is subjected to: (i) a surface nitriding treatment and (ii) a surface mechanical processing treatment, to obtain distinct microstructures and mechanical properties. These balls are subjected to RCF loading for several hundred million cycles at two different test temperatures, and the subsequent changes in subsurface hardness and compressive stress–strain response are measured. It was found that the RCF-affected subsurface regions grow larger in size at higher temperature. Micro-indentation hardness measurements within the RCF-affected regions revealed an increase in hardness in all the three variants. The size of the RCF-affected region and intensity of hardening were the largest in the BL material and smallest in the mechanically processed (MP) material. Based on Goodman's diagram, it is shown that the compressive residual stress reduces the effective fully reversed alternating stress amplitude and thereby retards the initiation and evolution of subsurface plasticity within the material during RCF loading. It is quantitatively shown that high material hardness and compressive residual stress are greatly beneficial for enhancing the RCF life of bearings.
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TL;DR: In this paper, the role of brittleness in white etching matter was determined by electron microscopy, which provided novel insights into cause-effect relationships and evolution mechanisms associated with white etchings.
Abstract: To determine the role of brittleness in producing “white etching matter,” rolling elements were intentionally case-carburize heat treated to produce an embrittled case. The intergranular embrittlement was confirmed by characterizing the fracture surfaces of the steel. Post rolling contact fatigue investigations showed subsurface cracks, forming preferentially along the grain boundaries, and white etching matter was determined to be present along these intergranular cracks. The white etching matter was characterized by electron microscopy. These results provide novel insights into cause-effect relationships and evolution mechanisms associated with white etching matter.
17 citations
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Abstract: The aim of the present investigation is to construct a constitutive model suitable for describing the cyclic behavior of 10Ni5CrMoV high-strength steel, which displays both cyclic softening and asymptotic ratcheting. Uniaixal tests of monotonic loading, symmetrical and asymmetrical strain cycling and stress controlled cyclic loading are conducted. Results reveal that the material exhibits non-saturated cyclic softening with combined nonlinear and linear softening rates, both isotropic and kinematic hardening are responsible for cyclic softening. A long period of steady-state ratcheting has been experimentally detected. Cyclic softening is found to have a considerable effect on the uniaxial ratcheting of the material. Significantly larger monotonic yield stress than that at cyclic loading is also observed. The dependence of cyclic softening on strain amplitude is revealed by a low-high sequence strain controlled cyclic test. Based on the experimental findings, a new constitutive model extended from Abdel-Karim–Ohno model has been constructed for 10Ni5CrMoV steel. The identification procedure of the material parameters is scrutinized critically by quantifying the contributions of the isotropic hardening and kinematic hardening on cyclic softening. Verification of the proposed model is achieved by simulating uniaxial strain and stress controlled cyclic loading tests. Fairly good modeling results are obtained. The superiority of the proposed model over other kinds of Ohno–Wang type models is also illustrated.
12 citations
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TL;DR: In this paper, an experimental methodology was proposed to measure the location and magnitude of cyclically evolving elastoplastic von Mises stresses in terms of micro-hardness numbers.
Abstract: The failure of a bearing-raceway assembly is governed by the spatial distribution of subsurface stresses at the vicinity of a bearing-raceway contact and the evolution of these stresses during rolling contact fatigue (RCF) loading. In this paper, we propose an experimental methodology that allows one to accurately measure the location and magnitude of the cyclically evolving elastoplastic von Mises stresses in terms of microhardness numbers. An M50NiL steel rod is subjected to RCF by three silicon nitride (Si3N4) balls for over several hundred million cycles at 5.5 GPa contact stress level. Microindentation hardness measurements within the subsurface RCF-affected regions of the rod revealed significant material hardening. A mechanistic methodology to construct a stress-life (S-N) diagram for RCF loading is proposed. S-N diagrams are constructed based on maximum von Mises stress amplitude and volume average von Mises stress amplitude. The effects of elastic modulus and yield strength gradient on stress fields are also considered in this analysis. Comparison of S-N diagrams based on both stress amplitudes indicates that the maximum von Mises stress amplitude overpredicts the fatigue strength of material in S-N diagrams. The experimental results obtained by following this methodology can help construct material hardening models for RCF, which may lead to an improved estimate of bearing fatigue life.
9 citations
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TL;DR: In this article, an analytical model was developed to determine the stress distribution over thickness for a multilayered thermal barrier coating (TBC) system deposited within a cylindrical reaction vessel.
Abstract: An analytical model was developed to determine the stress distribution over thickness for a multilayered thermal barrier coating (TBC) system deposited within a cylindrical reaction vessel. Temperature dependent material properties were used to estimate the stress values. It was found that, even for small lattice misfits, very high compressive elastic stresses could exist at the ceramic-bond coat interface immediately after deposition. Furthermore, this interfacial stress could ultimately relax to a lower value with increasing film thickness by dislocation nucleation. In the presence of a Thermally Grown Oxide (TGO), however, a tensile stress was generated within the oxide layer and discrete changes in stress profile were predicted at ceramic-TGO and TGO-bond coat interfaces. While the stress-change was higher at the ceramic-TGO interface for a high deposition temperature, the change was greater at the TGO-bond coat interface at a lower deposition temperature. A high compressive stress was predicted within the TGO layer upon cooling down the TBC system to room temperature and the stress-change was highest at the TGO-bond coat interface. Finally, when the TGO layer was subjected to fatigue loading under compressive mean stress during thermal cycling, the model predicted that the internal pressure of the cylindrical vessel reduces the magnitude of mean stress and increases the stress-range in the thermal stress cycle. The effects of evolved stresses on the context of interfacial failure of TBCs should provide fundamental insight into material selection and component design.
6 citations
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TL;DR: In this paper, it was shown that elastic-plastic stresses are significantly different from the elastic Hertz contact stresses, and that accounting for plastic deformation of the material necessitates significant correction in the material parameters used in the expressions for dynamic capacity calculations.
Abstract: Dynamic capacity, defined as the load under which rolling element bearing raceways will survive for 1 million revolutions with 90% probability of survival, is commonly used in bearing life-rating standards. This term was introduced by Lundberg and Palmgren to simplify life prediction equations, and was derived using the elastic Hertzian-theory of contact mechanics for earlier, relatively impure bearing materials. Modern ultra-clean steels with fewer impurities can survive for multi-millions of contact stress cycles, even under elastic-plastic loading conditions. Under such conditions, elastic-plastic stresses are significantly different from the elastic Hertz contact stresses. Current experimental and finite-element study, shows accounting for plastic deformation of the material necessitates significant correction in the material parameters used in the expressions for dynamic capacity calculations.
5 citations
References
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01 Jan 1972
TL;DR: Physical Metallurgy Principles as mentioned in this paper is intended for use in an introductory course in physical metallurgy and is designed for all engineering students at the junior or senior level and is largely theoretical, but covers all aspects of physical metelurgy and behavior of metals and alloys.
Abstract: Physical Metallurgy Principles is intended for use in an introductory course in physical metallurgy and is designed for all engineering students at the junior or senior level. The approach is largely theoretical, but covers all aspects of physical metallurgy and behavior of metals and alloys. The treatment used in this textbook is in harmony with a more fundamental approach to engineering education.
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01 Jan 1980
TL;DR: In this paper, the authors present methods proven successful in practice, such as safe-life, fail-safe, forecasting of service reliability, monitoring, and inspection; macroscopic and microscopic aspects of fatigue behavior; principles for determining fatigue crack growth and final fracture; scatter of data and statistical methods; environmental factors; and fatigue of joints and compounds.
Abstract: Presents methods proven successful in practice. Covers design procedures, such as safe-life, fail-safe, forecasting of service reliability, monitoring, and inspection; macroscopic and microscopic aspects of fatigue behavior; principles for determining fatigue crack growth and final fracture; scatter of data and statistical methods; environmental factors; and fatigue of joints and compounds. Contains design do's and don'ts and example problems.
1,788 citations
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TL;DR: In this paper, the structure and properties of bearing steels prior to the point of service are first assessed and described in the context of steelmaking, manufacturing and engineering requirements, followed by a thorough critique of the damage mechanisms that operate during service and in accelerated tests.
Abstract: A casual metallurgist might be forgiven in believing that there are but a few basic types of steels used in the manufacture of some of the most technologically important engineering components, the rolling bearings. First the famous 1C–1.5Cr steel from which the majority of bearings are made. Its structure is apparently well-understood and the focus is on purity in order to avoid inclusions which initiate fatigue during rolling contact. Then there is the M50 steel and its variants, from which bearings which serve at slightly higher temperatures in aeroengines are manufactured, based on secondary-hardened martensite. The casual metallurgist would be wrong; there is a richness in the subject which inspires deep study. There are phenomena which are little understood, apparently incommensurate observations, some significant developments and other areas where convincing conclusions are difficult to reach. The subject seemed ready for a critical assessment; hence, this review. The structure and properties of bearing steels prior to the point of service are first assessed and described in the context of steelmaking, manufacturing and engineering requirements. This is followed by a thorough critique of the damage mechanisms that operate during service and in accelerated tests.
556 citations
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TL;DR: In this article, it is shown that indentation hardness of ductile materials is essentially a measure of their plastic properties, rather than the brittle properties of the material. And the Mohs scratch hardness scale is used to measure the plastic properties of a material.
Abstract: This review is concerned with the basic physical meaning of hardness. It is shown that indentation hardness of ductile materials is essentially a measure of their plastic properties. With brittle solids the high hydrostatic pressures around the deformed region are often sufficient to inhibit brittle fracture. Under these conditions both indentation and scratch hardness are essentially a measure of the plastic rather than the brittle properties of the solid. This provides a simple physical basis for the Mohs scratch hardness scale
522 citations
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TL;DR: In this article, some of the most widely used RCF models are reviewed and discussed, and their limitations are addressed, and the modeling approaches recently proposed by the authors to develop life models and better understanding of the RCF.
Abstract: Ball and rolling element bearings are perhaps the most widely used components in industrial machinery. They are used to support load and allow relative motion inherent in the mechanism to take place. Subsurface originated spalling has been recognized as one of the main modes of failure for rolling contact fatigue (RCF) of bearings. In the past few decades a significant number of investigators have attempted to determine the physical mechanisms involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives. In this paper, some of the most widely used RCF models are reviewed and discussed, and their limitations are addressed. The paper also presents the modeling approaches recently proposed by the authors to develop life models and better understanding of the RCF.
352 citations