Fatigue Spalling Research Articles

Degradation mechanism of quenched-partitioning-tempered steel during sliding wear

Quenched-partitioning-tempered (Q-P-T) steel, with a combination of high strength and high toughness, is a potential wear-resistant material. However, there is disagreement that Q-P-T steels could replace conventional wear-resistant materials due to its unclear degradation mechanism during sliding wear. To promote the application of Q-P-T steel, the relationship between its microstructure obtained at different partitioning temperatures, microstructural damage behavior during sliding wear, and wear resistance was investigated. The results showed that the fatigue spalling was the main cause of the volume loss because of the formation of deformed layer consisting of equiaxed nanocrystals in the worn subsurface. Moreover, as the fatigue cracks nucleated and propagated at the interface of deformed layer/matrix, improving the matrix’s impact toughness can retard the formation of fatigue crack. The Charpy impact energy of Q-P-T steel first increased and then decreased with the elevation of partitioning temperature for the transformation of residual austenite morphology, achieving a maximum of 41 J at 280 °C. Consequently, the wear volume decreased and then increased with increasing partitioning temperature, showing a minimum value at 280 °C.

Research on Multi-Directional Spalling Evolution Analysis Method for Angular Ball Bearing

The prediction of spalling failure evolution in the lifespan of aeroengine bearings is crucial for en-suring the safe return of aircrafts after such failures occur. This study examines the spalling failure evolution process in bearings by integrating the proposed spalling region contact stress analysis model with the multi-directional subsurface crack extension analysis model. The results elucidate the general pattern of spalling expansion. Utilizing this methodology, the fatigue spalling fault evolution in bearings is thoroughly analyzed. Additionally, a two-dimensional model has been developed to simulate and analyze crack propagation in the critical direction of the spalling region, significantly enhancing the model’s computational efficiency.

A Comparative Study on the Wear Behavior of Quenched-and-Partitioned Steel (Q&P) and Martensite Steel (Q&T)

The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The results show that abrasive ploughing was the main reason causing the material loss of Q&P and Q&T steel, while Q&T steel was subjected to severe fatigue spalling in the impact abrasive wear tests. Under the abrasive wear test, Q&T steel has better wear resistance due to its higher initial hardness. Under the impact abrasive wear test, Q&P steel has better wear resistance. This is because the formation of the deformed layer, which consists of finer grains and newly formed martensite in the worn subsurface, increased the hardness of the Q&P steel, causing the hardness of the worn subsurface in Q&P steel to be higher than that of Q&T steel. Furthermore, Q&P steel has better resistance to cracks nucleation and propagation compared to Q&T steel. As a result, less material loss was caused by fatigue spalling in Q&P steel under the impact abrasive wear tests.

Effect of combined laser shock peening and nitrogen implantation on the microstructure and tribology of M50 bearing steel

The M50 bearing steel underwent a combined treatment of laser shock peening (LSP) and nitrogen ion implantation. The microstructure, surface mechanical properties and tribological behaviors were evaluated. Comparative analysis with the untreated sample revealed significant improvements in surface nano-hardness, increasing from 7.51 GPa to 11.35 GPa, 11.51 GPa, and 12.62 GPa for samples subjected to LSP, ion implantation, and combined strengthening, respectively. Correspondingly, surface compressive residual stress showed notable increases from −15.55 MPa to −1043.76 MPa, −451.34 MPa, and −1276.13 MPa, respectively. The improved surface mechanical properties observed in the combined strengthened sample are likely due to the synergistic effects of the combined strengthening. In friction tests, the combined strengthened sample exhibited the lowest friction coefficient, attributed to the presence of a metal nitride layer and a thicker amorphous layer. Wear mechanisms transitioned from fatigue spalling for the untreated specimen to slight wear and the formation of an oxidative adhesion layer after LSP and ion implantation. Remarkably, the surface of the combined strengthened specimen demonstrated minimal wear, with only an oxidative adhesion layer present.

Rolling contact fatigue analysis of the soft zone for the main bearing in a tunnel boring machine

A hierarchical finite element modeling method is proposed to study the problem of fatigue spalling easily due to low hardness in the soft zone for the main bearing of a tunnel boring machine. Quasi-static analyses of the main bearing are performed based on the global symmetric model and verified by relative displacement tests of the rings. The invariant contact pressure is replaced by the rolling contact of the rollers in the local sub-model. The contact load is used as an input to solve the stress field, and then the effects of soft zone and hardened depth on the contact characteristics and fatigue lifetime of the sub-model are investigated. The results show there are stress peaks at the junction of the hardened and soft zones. The effect of hardened depth on the stress distribution and fatigue lifetime is relatively small. However, the optimum hardened depth is influenced by the contact load and the permissible stress of the material. The minimum lifetime of the raceway during rolling occurs in the soft zone. This paper achieves a fast and effective rolling contact fatigue analysis of the main bearing, which provides a theoretical basis for optimizing the main bearing design.

Impact-abrasive wear property of ZrO2 toughened Al2O3 ceramic particles reinforced high manganese steel matrix composites

ZrO2-toughened Al2O3 (ZTA) ceramic particle–reinforced high manganese steel (HMS) matrix composites are a promising class of wear-resistant structural materials for various purposes such as mining. In this study, millimeter-scale ZTA/HMS composites were prepared by cast infiltration method. Using SEM, EPMA, TEM, nanoindentation, a microhardness tester, and an impact-abrasive wear machine, the microscopic characteristics of interfacial layers, work-hardening behaviors, impact-abrasive wear properties, and wear failure mechanism were investigated. The results show a smooth and continuous interfacial layer between ZTA and the matrix. This layer is dominated by an amorphous structure, and the hardness and modulus of the interfacial layer reached 6 and 200 GPa, respectively. The relative wear resistance of the composites under impact (energies of 2–5 J) was between 2.17 and 0.59, and the depth of the work-hardening layer amounted to 0.95–2.95 mm. The wear failure mechanism of the composites was as follows: at a low impact energy (2 J), micro-cutting, grooving, fatigue spalling, and wedge formation occurred. When the impact energy was increased to 5 J, the wear mechanism of the composites was dominated by the breaking and shedding of the ZTA particles. This study has practical importance because it is based on the problems and needs of composites in actual production.

Low and high temperature effects on friction and wear performance of Cr-plated cylinder liner

Cr-plated cylinder liners with good wear and corrosion resistance as well as high strength are suitable for application in low-carbon fuel engines. A reciprocating friction and wear tester was used to measure the friction and wear performance of the Mo-sprayed piston ring and Cr-plated cylinder liner at low and high temperatures. For the low temperature conditions from −20 °C to 20 °C, the worn surface of tribo-pair was more prone to spalling. Once the load went up to 66 MPa under low temperatures, cylinder liner scuffing occurred. As the temperature increased from 90 °C to 240 °C, the honing textures of the Cr-plated cylinder liner presented gradually shallow with more abrasive marks along the sliding direction. The tribo-chemical reaction products of zinc dialkyldithiophosphates (ZDDP) with white bright spots distribution provided better protection of the tribo-pair to avoid severe fatigue spalling. The influence of temperature effects on the ZDDP decomposition and surface spalling damage should not be underestimated for Cr-plated cylinder liners.

Effect of multiple factors on sediment erosion characteristics of hydro turbine materials

Hydraulic turbines on sediment-laden rivers suffer from cavitation-silt erosion. This study conducted cavitation-silt erosion tests on three materials (06Cr16Ni5Mo, Q355B, 06Cr20Ni11) with different sediment concentrations and impact velocities using a rotating disk facility, and used a scanning electron microscope (SEM) to observe the cavitation-silt erosion characteristics of the materials. The results show that the cumulative weight loss of all materials continuously increases with the sediment concentration and impact velocity rises. The weight loss of 06Cr16Ni5Mo is the lowest, and 06Cr20Ni11 is the highest. As the impact velocity rises, the cumulative weight loss increases exponentially. As the sediment concentration rises, there are obvious scour marks and fatigue spalling on the material surface. As the impact velocity rises, the size and depth of micro-cutting marks and cavitation pits increases. Due to the lower surface hardness of 06Cr20Ni11, the deep platelet pits appear on the material surface.

Properties and elevated temperature wear mechanism of pure copper and TiC/Cu nanocomposites

The properties and elevated temperature wear mechanism of pure copper and in situ TiC/Cu matrix composites fabricated via combustion synthesis assisted with hot press were investigated. Brinell hardness, compression properties and electrical conductivity were studied. It was found that of the Brinell hardness, yield strength and compressive strength of the composites is higher than sintered pure copper, however, the electrical conductivity and fracture strain of the composites are lower. Dry sliding friction and wear tests showed that the worn surface transformed from furrow to spalling pit and the wear rate increases with the increasing temperature and applied load, the wear failure changes gradually from surface plastic deformation, plough wear and oxidation wear to abrasive wear and fatigue spalling wear.

Wear Properties of Metal Material in Dredging Equipment

In dredging engineering, the parts of dredging and conveying system which contact with dredging mixture often suffer from serious wear and short service life. In order to improve the durability of materials, new materials and generation processes are constantly proposed. It is always a difficult work to analyze the wear properties and mechanism of materials.In this paper, dry friction and abrasive wear tests were carried out on Cr15, Cr26, Fedur®40, medium manganese steel and XGG with Q235 carbon steel as the comparison material. The wear mechanism of materials was analyzed by scanning electron microscope (SEM) observation on the wear surface of materials. Under the test conditions, the dry friction wear rates of the five materials were 6.98×10−6 mm3/Nm,5.71×10−6 mm3/Nm,20.2×10−6 mm3/Nm,21.9×10−6 mm3/Nm and 5.39×10−6 mm3/Nm respectively.The wear rates of abrasive wear tests were 58.3×10−6 mm3/Nm,25.2×10−6 mm3/Nm,83.4×10−6 mm3/Nm,30.9×10−6 mm3/Nm and 32.1×10−6 mm3/Nm respectively. The results show that the metal surface is covered with coarse and deep cutting and chipping marks under abrasive wear, while the metal surface only has fine furrowing and a little fatigue spalling under dry friction wear. The wear rate of abrasive wear of five wear-resistant materials is much higher than that of dry friction wear. Cr26 and XGG showed better wear performance than other materials under the two test conditions.

Microstructural changes and dry sliding wear behavior of Cu-15Ni-8Sn-0.5Co alloy during deformation and aging treatment

The microstructural evolution and dry friction wear performance of the Cu-15Ni-8Sn-0.5Co alloy during deformation and aging treatment were studied using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and three-dimensional surface profilometry. The results show that the peak hardness of the Cu-15Ni-8Sn-0.5Co alloy initially increases and then decreases with increasing cold deformation, reaching a maximum hardness of 440 HV at 70 % cold deformation. During the aging process at 400 ℃, the phase transformation sequence of the Cu-15Ni-8Sn-0.5Co alloy with 70 % cold deformation is as follows: modulated structure - D022 ordered phase - γ-D03 phase. The rapid formation of the D022 ordered phase, which is coherently dispersed within the matrix, is the main reason for the significant improvement in the mechanical properties of the alloy. However, the rapid nucleation and growth of the discontinuous precipitation structure are responsible for the reduced mechanical performance and limited resistance to over-aging in the alloy. Additionally, it also causes decreased friction and wear resistance in the alloy with 70 % cold deformation. At a load of 20 N, the primary wear mechanism of the peak-aged Cu-15Ni-8Sn-0.5Co alloy with 70 % cold deformation is abrasive wear. As the load increased to 120 N, the wear mechanism shifted to a combination of abrasive wear and fatigue spalling wear in the alloy.

Dynamic modeling and vibration analysis of an RV reducer with defective needle roller bearings

The rotate vector (RV) reducer's needle roller bearings (NRBs) are vulnerable to wear and flaws such as fatigue spalling of the raceway material. Studying the vibration mechanism and the excitation laws of NRB failures is essential to enhancing the RV reducer's performance and comprehending its operating state. This paper presents a dynamic model of the RV reducer based on the theory of contact multibody dynamics. It integrates internal and external raceway defects and takes into account the synchronous contact interaction between NRB groups and the crankshaft and cycloidal gears, as well as the time-varying mesh stiffness in the planetary gear transmission and cycloidal pin transmission. The study demonstrates that the rolling of bearings and the meshing of internal transmission components are the primary causes of vibration in a healthy RV reducer through experimental verification and dynamic simulation analysis of the system with and without NRB failures. Both the crankshaft rotation frequency and the cycloidal gear rotation frequency affect the vibration excitation source's characteristic frequency. The vibration amplitude of the RV reducer is influenced by bearing flaws on a periodic basis. The impact of internal raceway defects is greater than that of external raceway faults, resulting in a notable rise in vibration amplitude.

Effects of B content on wear and corrosion resistance of laser-cladded Co-based alloy coatings

Abstract To improve the surface properties of Ti alloy, (Co34Fe8Cr29Ni8Si7)100–x B x alloy, coatings were prepared by laser cladding. The coatings—mainly composed of TiCr, Fe0.1Ti0.18V0.72, CoTi, Ti2Ni, and TiB—and amorphous phases were investigated in terms of microstructure, wear resistance, and corrosion resistance. The results showed that the microhardness of the Co-based coatings first increased and then decreased with the increase of B content. When the B content was 6%, the microhardness of the coating increased up to 1210 HV0.2 which was 3.4 times that of TC4 alloy substrate. The coatings exhibited diverse wear mechanisms that gradually transitioned from severe fatigue spalling and oxidative wear to slightly abrasive wear. The corrosion current density of Co-based coatings in 3.5 wt% NaCl solution first increased and then decreased as B contents increased. Coatings with 4% B content, however, exhibited the best corrosion resistance, which was most suitable for improving the corrosion resistance of Ti alloy.

Effect of ultrasonic impact treatment on the microstructure and properties of laser cladded CoCrFeNiMox high entropy alloy coatings

Ultrasonic impact technology was applied to improve the property of laser cladded CoCrFeNiMox (x = 0, 0.25, 0.5, 0.75) high entropy alloy coatings on the surface of low-carbon steel. The phase structures and the microstructural characteristics were studied in detail through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness distributions, wear resistance, and corrosion resistance of the samples are illustrated using a microhardness tester, a micro-friction and wear tester, and an electrochemical test system. Single FCC phase solid solution was identified to be the main phase structure, with the interdendritic σ phase precipitating with the increasing Mo content. Although ultrasonic impact treatment did not change the phase composition of the high-entropy alloy (HEA) cladding coatings, evident plastic deformation and broken σ phase appeared near the surface of the impacted layers. Through the combined effects of dislocation, fine-grain, and dispersion strengthening, the microhardness of the CoCrFeNiMox coatings was improved after ultrasonic impact treatment. In addition, ultrasonic impact treatment decreased the surface roughness and increased the wear resistance, and the main wear mechanism of the impacted layers changed from fatigue spalling to abrasive wear. The wear mass of the ultrasonically impacted layers was approximately 92 % of the laser cladded CoCrFeNiMox coatings. Furthermore, ultrasonic impact treatment improved the corrosion resistance of the HEA coatings.

Preparation and Impact‐Abrasive Wear Behavior of NbC‐Reinforced Iron Matrix Composites

Workpieces in the field of mining machinery are prone to failure under the combined effect of impact and abrasive, causing serious economic losses to enterprises. In this study, both pure Fe matrix composites and NbC particle (NbCp)‐reinforced Fe composites (NbCp/Fe) samples are produced by vacuum‐sintering method, respectively, and their resistance to impact‐abrasive wear is tested on the impact‐abrasive wear rig. In the results, it is shown that the hardness of NbCp/Fe composite increases with the increase of NbCp mass fraction, and the density decreases when the mass fraction of NbCp is less than 7%. At this time, the homogeneity of the composite is higher; when the mass fraction of NbCp is greater than 7%, the standard deviation values of hardness and density are larger, fluctuate greatly, and have low uniformity, and agglomeration occurs within the organization; When the mass fraction of NbCp is 7%, composite possesses better comprehensive performance. The impact‐abrasive wear mechanism of the Fe matrix material primarily includes microcutting, impact plastic deformation, and fatigue spalling, which is a typical abrasive wear mechanism; the impact‐abrasive wear mechanisms of NbCp/Fe composites primarily comprise microcutting or micro‐plowing, impact plastic deformation, and fatigue spalling.

Enhancing the wear and high-temperature oxidation behavior of NiCrBSi coatings by collaboratively adding WC and Cr3C2

A composite coating was deposited by collaborative modification with tungsten carbide (WC) and Cr3C2 ceramic particles to improve the wear resistance of NiCrBSi coating over a wide temperature range. The original NiCrBSi coating and the composite coatings with WC and Cr3C2 collaboratively (NiCrBSi +20 wt% WC–Cr3C2–Ni) and exclusively (NiCrBSi +20 wt% WC and NiCrBSi +20 wt% Cr3C2–NiCr) added were designed and deposited by plasma spraying. The microhardness of the composite coatings added with the ceramic phase was higher than that of the NiCrBSi coating. The composite coating with the addition of WC showed the maximum microhardness (896.8 HV). The wear mechanism of the four coatings at room temperature was dominated by fatigue spalling, whereas oxidative and abrasive wear prevailed at 700 °C. The composite coating (NiCrBSi +20 wt% WC–Cr3C2–Ni) showed excellent abrasion resistance at room temperature and 700 °C. The wear volume of the composite coating (NiCrBSi +20 wt% WC–Cr3C2–Ni) decreased by 83.5 % and 46.9 % at room temperature and 700 °C, respectively, compared with the wear volume of the NiCrBSi coating. In general, high WC hardness was favorable for improving the microhardness of the coating. The preferential oxidation of Cr3C2 instead of WC promoted the formation of a dense oxide film on the surface of the coating and reduced oxidation within the coating. This study revealed the mechanism of the collaborative enhancement of NiCrBSi coatings by WC and Cr3C2 and the improved wear resistance of the NiCrBSi coatings at room and high temperatures.

Investigation on the transient rolling contact behaviour of corrugated rail considering material work hardening

The process of work hardening in the corrugation zone of the steel rail results in an uneven distribution of hardness, with higher hardness in the corrugation troughs and lower hardness in the corrugation crests. To study the influence of hardness on the rolling contact behavior of the wheel-rail at corrugation zone, a three-dimensional wheel-rail transient rolling contact finite element model is established based on the measured corrugation and hardness distribution of the rail to reveal the influence of the non-uniform distribution of hardness at corrugation zone on the wheel-rail contact state and the wear and fatigue of the rail surface. The results indicate that: (1) work hardening in the corrugation zone leads to an increase in equivalent stress and strain within the contact patch between the wheel and rail. However, due to the increase in yield strength, plastic deformation and residual strain are somewhat reduced; (2) The uneven distribution of hardness in the corrugation zone results in an elevation of longitudinal shear strain between the wheel and rail, which may initiate tangential fatigue cracks and spalling of the steel rail surface; (3) the wear on the rail surface is large near the wave crest and small near the wave trough, work hardening will change the wear difference between the wave crest and wave trough while reducing the wear, resulting in the “peak shaving and valley filling” phenomenon developing faster in the early wave wear period and slower in the later period.

Surface treatment of rail to enhance rolling contact fatigue and wear resistance: Combined spot laminar plasma quenching and tempering method

The railway industry faces the challenge of improving the fatigue and wear resistance of rails simultaneously. Laminar plasma quenching (LPQ) can enhance wear resistance but may result in severe rolling contact fatigue (RCF) damage. This study proposes a combined LPQ and tempering method to address this issue and evaluates its effect on rail RCF damage and wear resistance using twin-disc tests. The findings demonstrate that tempering diminishes the grain density and mitigates the lattice distortion in the quenched zone of LPQ rails, thereby enhancing the RCF resistance in that zone. This treatment leads to a substantial reduction in surface fatigue cracks and spalling of the rails and a wear resistance improvement of over one-fold compared to ordinary rails. Thus, this rail surface treatment approach effectively improves both the fatigue and wear resistance of rails simultaneously.

Effect of heat treatment on the microstructure, impact toughness and wear resistance of Fe-based/B4C composite coating by vacuum cladding

The study focused on the effect of quenching and quenching-tempering processes on the microstructure, hardness, impact toughness and wear resistance of Fe-based/B4C composite coating on the surface of ASTM 1045 steel by vacuum cladding. The results revealed that the metallurgical bonding was realized between the coating and steel substrate. After quenching at 950/1000/1050 °C and quenching-tempering at 1000–490/1000–540/1000–590 °C, the hard phases (M2B and M23 (C, B) 6) in the coating remained unchanged in type, but their morphologies were broken and became more rounded. The coating matrix changed from pearlite to martensite, and granular secondary phases of M23(C, B)6 precipitated from coating matrix. After heat treatment, the impact energy of coated samples is significantly improved, which may be related to the evolution of the coating microstructure and the appearance of interfacial delamination fracture. The results of the wear test showed that the change of coating matrix and hard phase morphology, and the coordination between them were the main factors affecting the wear resistance of the coating. The best wear resistance of the coating was obtained at QT540, and the wear mechanisms were mainly fatigue spalling and brittle fracture.

Effect of Ni additions on microstructure, interfacial diffusion behavior and properties of Fe-based/B4C composite coating by vacuum cladding

In order to improve the hardenability and toughness of Fe-based/B 4 C composite coatings, which were bonded on ASTM 1045 steel by vacuum cladding, nNi ( n = 0, 1, 3, 5, weight %) were added into the coatings. The influences of Ni additions on the microstructures, interfacial diffusion behavior, impact toughness and three-body abrasive wear behavior of composite coatings were investigated systematically. The results indicated that coatings were completely fused with steel substrate without micro-defects. When the amount of Ni was increased, the activity of the C atom on the coating side was enhanced, the decarburization zone near the interface disappeared, and the metallurgical bonding state of interface was strengthened. Furthermore, the increment of Ni improved the hardenability of coating and promoted the transformation from pearlite to martensite in the matrix structure of the coating. The impact toughness of the coating samples also increased with the increment of Ni additions, and reached the maximum of 4.8 J/cm 2 at 5Ni sample. The three-body abrasive wear test implied that when 3 wt% Ni was added to the coating, the mass loss was 0.14 g, which was much lower than that of other samples and exhibited the best wear resistance. The wear mechanism of coatings changed from partial plastic cutting and fatigue spalling to single fatigue spalling. • Ni addition strengthens the metallurgical bonding state of the coating interface. • The increase of Ni addition improves the hardenability of the coating matrix. • Ni addition improves the impact toughness and wear resistance of the coating.