Rolling contact fatigue (RCF) is one of the main rail damage forms. Severe RCF damage can cause rail fracture and seriously endanger the safety of train operation. In this study, the influence mechanism of bending stress on RCF propagation of rail was studied. Firstly, a twin-disc rolling rail specimen considering bending stress was designed by finite element (FE) simulation, and the bending stress was introduced into the twin-disc rolling test. Secondly, the evolution behavior of RCF crack propagation of rail under bending stress and the comparative study of RCF crack propagation behavior of rail under different crack propagation driving forces were carried out by using the twin-disc rolling rail specimen considering bending stress and traditional twin-disc rolling wheel-rail specimen. Results indicate that the bending stress had a significant effect on the initiation and propagation of the RCF crack of the rail. Compared with the non-bending stress affected zone (NBSA zone), the bending stress promoted the initiation of cracks and drove them to propagate rapidly along the plastic deformation layer. When the crack propagation depth was greater than the thickness of the plastic deformation layer, the crack had an obvious tendency to propagate inside the material, which was manifested as the crack propagating almost perpendicular to the rail surface. Compared with the crack behavior only under contact stress, the angle and depth of crack propagation increased significantly under bending stress, indicating that the bending stress promoted the crack propagation. Compared with the crack propagation behavior under water medium, the crack propagation under bending stress was directional, and the crack propagation behavior was highly consistent with the crack propagation of field rail.

Abstract Rolling contact fatigue (RCF) damage is a critical damage form faced by rails, especially under rainy and humid conditions. To deeply explore the mechanisms of RCF damage under such conditions, a novel wet–dry alternation testing method (D/W-A test) was proposed, and damage evolution tests of rail RCF were conducted in this study. Detailed comparisons between the novel testing method and three widely used rail RCF methods were analyzed. The results show that under wet–dry alternating conditions, the crack growth rate and wear rate were initially low, with cracks predominantly located in the region near the rail surface. Thus, there was a significant competitive relationship between crack propagation and wear in this period. Then, with increasing number of cycles, RCF damage was gradually dominated by crack propagation, which extended deeper into the material along its deformation orientation. Meanwhile, severe material spalling led to a rapid increase in the wear rate. Through comparative analysis of the accuracy, repeatability, evaluability, rationality, and practicability of the four testing methods, it was found that the novel method proposed in this study had significant advantages in rationality and accuracy compared with traditional RCF testing methods, providing a more effective tool for systematic studies on the RCF performance of rail materials.

Wheel rolling contact fatigue (RCF) damage behaviour directly affected the efficiency and safety of heavy-haul railway train operation. This study aims to investigate the correlation between wheel material plastic deformation and RCF damage evolution using a twin-disc wheel-rail rolling contact testing machine. Three kinds of heavy-haul train wheels (J1, J1+Mo and J12+V) were used to further study the effect of material characteristics on wheel RCF damage behaviour. Results indicated that during the whole evolution period, RCF cracks initiated at the wheel material surface due to the larger content of High-angle Grain Boundaries, and then further propagation was promoted by grains with large Local Misorientation and Schmid factor value enriched at the crack tip. Based on the changing trend of material deformation and RCF crack characteristics, wheel RCF damage evolution can be divided into initiation, intensification and stabilization periods. Meanwhile, Pearson correlation coefficients between plastic deformation layer thickness and surface crack width and crack depth reached 0.933 and 0.928 (p<0.01), respectively. In the stabilization period, the partial correlation coefficients of pearlite interlamellar spacing and ferrite volume fraction with crack depth were as high as 0.983 and 0.965 (p<0.01). After stabilization, the plastic deformation layer thickness of J1, J1+Mo and J12+V is about 230-240 mu m, 210 mu m and 190 mu m, and the surface crack width was about 600 mu m, 400 mu m and 370 mu m, respectively. J12+V with C and V addition showed the smallest plastic deformation and the weakest RCF damage. These results provide practical guidance for optimizing wheel material selection in heavy-haul railways.

Particle suspension stability is essential for the performance of functional fluids, but sedimentation failure is often induced by thermal fluctuations. In this study, the thermal stability and degradation mechanisms of a water-based suspension comprising water, sodium carboxymethyl cellulose (NaCMC), inorganic particles, and acrylic polymer emulsion are investigated under alternating temperature cycles (80 degrees C and -20 degrees C). Results found that suspension stability is significantly reduced by thermal conditions. The rheological and physical properties, including viscosity, particle content, and density, are altered during this process. The ageing is identified in three stages: i) unaged-no significant changes; microstructure uniformly dispersed; ii) mild ageing-viscosity changed markedly while particle content and density stayed stable, "Flocculent" structures appeared; iii) severe ageing: viscosity changed at a maximum rate, with pronounced variations in particle content and density. The "flocculent" structure developed into "snowflake crystals". It is revealed by mechanism analysis that the long-chain NaCMC network is degraded by thermal cycles. Consequently, the protective polymer network is destroyed, leading to irreversible particle aggregation and sedimentation. These findings provide insights into the thermal degradation of water-based polymer suspensions. A theoretical basis is offered for improving the stability of such a functional suspension.

Water-based friction modifiers (FMs) are widely used in wheel-rail friction management. They may suffer from suspension stability degradation, but the influence of this on their tribological performance has not been systematically clarified. In this study, the performance evolution of a water-based FM during suspension stability degradation was investigated using a twin-disc rolling-sliding wear tester. Friction control performance, wear rates, and rolling contact fatigue (RCF) damage were evaluated for undegraded and degraded FM samples collected from the top and bottom layers of their container post ”settling”. The results show that all FM samples reduced the friction coefficient compared with the dry condition, while the corresponding wear and RCF responses varied markedly with degradation severity and sampling layer. The undegraded FM exhibited a balanced performance, reducing both wear and RCF damage. Under the slightly degraded stage, the top- and bottom-layer samples exhibited similar friction control and wear behaviour to each other, but both produced severe RCF damage. Under the moderately and severely degraded stages, pronounced differences emerged between the top-layer and bottom-layer samples, and these differences became more significant with increasing degradation severity. In general, the tribological balance of the FM deteriorated after degradation, and in some cases led to increased wear and aggravated RCF damage.

High-strength bainitic steel is expected to serve as an effective rail material for mitigating rolling contact fatigue (RCF) in heavy-haul railway systems. To systematically investigate the RCF crack propagation characteristics of the high strength bainitic rail (tensile strength >= 1380 MPa), laboratory metallographic microscopic analysis on the field service lath bainitic rail in a trial section on a mining line was first conducted. The damage analysis revealed that despite the relatively mild RCF damage observed on the rail surface, some RCF cracks showed steep propagation angles (70-80 degrees) even at depths of only about 100 mu m, whereas most other cracks remained significantly shallower. Then, to investigate whether the distinctive RCF damage characteristics were associated with the intrinsic material properties of the lath bainitic rail, a series of RCF crack propagation tests were conducted under varying simulated axle loads and compared with granular bainitic rail (tensile strength >= 1250 MPa) and eutectoid pearlitic rail steel (tensile strength >= 1180 MPa). The results showed that the lath bainitic rail exhibited the mildest RCF damage, followed by the granular bainitic rail, whereas the eutectoid rail experienced the most severe damage, characterized by dense network-like cracks. Under a 30-t axle load, most cracks in the lath bainitic rail remained shallow due to the limited deformation of its dense lath-bainitic, and many of them propagated at steep angles with depths generally less than 100 mu m. However, a small number of cracks propagated into the matrix layer, resulting in depths exceeding 400 mu m and forming deep C-shaped cracks with limited branching due to stress concentration. In summary, the excellent resistance to deformation of high-strength lath bainitic rails may contribute to an increased risk that RCF damage develops into deep cracks.

The evolution of microstructure influences rolling contact fatigue (RCF) crack propagation behavior. This study aims to investigate the effect of pearlite and proeutectoid ferrite on crack propagation in hypoeutectoid rails. The dry-wet alternation RCF tests were conducted using different hypoeutectoid rail steels to simulate crack propagation within the deformation and matrix layers. Subsequently, the relationship between microstructure characteristics (proeutectoid ferrite content (PF%) and pearlite interlamellar spacing (ILS)) and crack propagation behaviors (crack characteristics and propagation modes) was explored using statistical analysis. The results indicated that proeutectoid ferrite played a crucial role in determining crack propagation paths. Specifically, a higher PF% facilitated crack propagation at a smaller angle within the deformation layer, while also promoting more pronounced branching in the matrix layer. Crack propagation along proeutectoid ferrite exhibited a greater tendency, as evidenced by its proportion being approximately four times that of PF%. Moreover, in the deformation layer, proeutectoid ferrite was stretched into plastic flow lines that served as grain boundaries, which can suppress the upward crack propagation. The reduction of ILS would decrease the degree of deformation, crack depth, and the proportion of transgranular propagation. Within the matrix layer, the rail steels with a lower ILS exhibited a notable reduction in the proportion of transgranular propagation, causing the crack propagation along pearlite lamellae with lower energy dissipation.

As high-speed railways expand into steep mountainous regions, the wheel-rail system must not only address low adhesion caused by liquid media (water and oil) in an open environment but also ensure traction and braking capability on steep gradients. Sanding is an effective method to improve wheel-rail adhesion. This study examined the effect of liquid media and sanding particles on wheel-rail adhesion behavior under track ramp conditions using a novel 1:5 scale wheel-rail rolling contact experimental machine. The results indicated that, under dry and water conditions, with the increase in track gradient, the adhesion coefficient decreased. However, under oil conditions, the track gradient had little influence on the adhesion coefficient. At the same track gradient, the adhesion coefficient on the ascent was higher than on the descent conditions. Furthermore, sanding notably increased the adhesion coefficient under low adhesion conditions, but the adhesion improvement effect was affected by the particle distribution density, size, and type. Specifically, under water conditions, at a 0% track gradient, with the increase in the particle distribution density, the adhesion coefficient increased, but it decreased when the distribution density exceeded a threshold; Smaller particle size silica sand showed the best adhesion improvement. When the track gradient increased to 5%, the influence trend of the particle distribution density and particle size on adhesion coefficient under water and oil conditions was consistent with that at 0% track gradient. Furthermore, random forest importance analysis indicated that particle distribution density should be prioritized for adhesion improvement under track ramp conditions when water or oil is present at the wheel-rail interface. Within the tested range of the present 1:5 scaled experiments, S-sized silica sand at 0.2 g/m under water conditions and M-sized silica sand at 1.0 g/m under oil conditions showed better adhesion improvement performance.

Rail flash-butt welded joints are susceptible to rolling contact fatigue (RCF), which may threaten train operation safety. A series of twin-disc rolling contact tests were carried out under different cycle numbers on welded U78CrVH rail to investigate the RCF evolution of flash-butt welded joint. The welded joint comprises four zones and exhibits a symmetrical distribution relative to the weld bond line. The hardness values of the bond line, normalized zone, softened zone and base metal are 357 f 6, 413 f 14, 335 f 17 and 412 f 15 HV0.5, respectively. The results showed that with increasing cycle number, the welded joint gradually developed increasingly non-uniform damage. In the bond line, damage evolved from early subsurface crack initiation along proeutectoid ferrite flow lines to dominant crack growth and finally severe lamellar spalling. In the normalized zone, damage mainly evolved through the accumulation of typical near-surface RCF cracks. In the softened zone, damage evolved from early plastic deformation and subsurface crack formation to crack coalescence and finally local spalling. In the base metal, deformation was mainly accommodated by deeper plastic flow, resulting in relatively limited crack propagation. These zone-dependent damage forms were controlled by local microstructure. These results provide a basis for defect identification and welded joint maintenance and in the longerterm developing solutions to reduce the problems.

This study proposes an on-orbit radiative spectral performance evaluation method for the Greenhouse Gas Monitoring Instrument (GMI) payload. Firstly, based on the SCIATRAN (Scientific Computing of Atmospheric Radiative Transfer and Applications) radiative transfer model, a forward simulation of high-resolution reference spectra was conducted by considering surface reflectance and atmospheric composition parameters, providing a benchmark for performance evaluation. Next, four core evaluation metrics were proposed: relative radiometric accuracy (k), absolute radiometric accuracy (RMSE), spectral offset (Delta lambda), and spectral shape matching accuracy (SSM), which comprehensively quantify the differences in radiance intensity and spectral shape between the payload-observed spectra and the reference spectra. Using this method, a detailed analysis of the on-orbit performance of the GMI payload onboard the GaoFen-5B satellite was conducted in this study. The research results indicate that there are certain issues with the on-orbit performance of the GF-5B GMI: the O2 channel exhibits relatively stable performance but with spectral shape distortion; the CO2-1 channel shows more significant spectral distortion, accompanied by some degree of deviation; while the spectral offset in the CO2-2 channel is even more pronounced, and over time, the spectral shape has undergone significant changes, indicating severe performance degradation.

Due to the fact that trains operate in a complex environment with the presence of the third-body media (e.g., rain, leaves, oil, and antifreeze for track inspection in winter), low adhesion can occur at the wheel-rail interface, leading to a large slip ratio, which could cause severe wheel and/or rail damage. To help find a solution to this problem, wheel-rail dynamic adhesion characteristic tests were conducted under various third-body media conditions (dry, water, oil, leaves, and antifreeze) using wheel-rail rolling wear and contact fatigue testing machines. The results indicated that the adhesion curve exhibited a double peak in the loading stage under both dry and water conditions. However, under the other conditions (oil, leaves, and antifreeze), the adhesion characteristic curves were all single peak curves. Under the water conditions, the adhesion coefficient in the unloading stage was higher than in the loading stage, and the second peak point in the loading stage was higher than the first peak point. This phenomenon was related to the water volume at the wheel-rail interface, which affected the thickness of the water film. However, under dry conditions, the adhesion coefficient in the unloading stage was lower than in the loading stage, attributed to the formation and removal of oxides on the wheel-rail surface. Additionally, a wheel-rail adhesion model for the large slip ratio range was established, which provided the foundation for theoretical research on wheel-rail adhesion and for the design of locomotive adhesion control methods.

Evaluation and prediction of wheel-rail rolling contact fatigue (RCF) damage can provide important theoretical guarantees for the service safety of wheels and rails and help make maintenance easier to plan. This study aims to develop a novel method for evaluating and predicting RCF damage of the pearlite rail materials with various initial shear yield strengths (ke). Based on the rough set mathematical theory incorporated within the cloud model of the comprehensive evaluation index (P0/ke*mu t), a novel evaluation and prediction method for RCF damage states of various pearlite rail materials was constructed using the shakedown limits for pearlite rail materials with various initial shear yield strengths. To develop this novel prediction method, different evaluation indices for RCF damage states were designed. A comprehensive certainty approach was introduced to quantitatively analyze the actual measured values of distinct evaluation indices that corresponds to different RCF damage states, wherein the maximum value rule was applied. Moreover, the prediction results were confirmed after further verifying using the actual measured value of the P0/ke*mu t. The results indicated that the predicted results were consistent with the test outcomes. The key feature of this prediction method was that it involved both the intrinsic shear yield strength of evaluated pearlite rail materials and wheel-rail rolling contact variables. On the basis of the two-dimensional classical shakedown map, a three-dimensional shakedown limit diagram for rail materials with varying initial shear yield strengths was further constructed using this novel prediction method. The three-dimensional shakedown limit diagram featured an inclined curved surface. As the initial shear yield strength of the pearlite rail materials increased, the curved surface tilted downward, indicating that an increase in the initial ke value of the pearlite rail materials could result in a lower shakedown limit.

Wear and rolling contact fatigue (RCF) are two primary forms of rail damage. In this study, the relationship between wear and RCF damage was investigated, using an MJP rolling contact wear and fatigue testing machine. The experiments were conducted under dry-wet alternation conditions with various dry-wet time ratios, contact stresses, and slip ratios. The results indicated that as the dry-wet duration ratio increased, crack propagation was significantly accelerated due to the oil wedge effect, while wear initially increased before decreasing, reaching its peak when severe peeling occurred on the rail surface. With the increase in contact stress, the crack depth grew stably, while the wear depth initially increased gradually and then accelerated by large-scale severe spalling pits. As the slip ratio increased, rail wear exhibited a continuous increase, while crack depth initially increased but then decreased rapidly due to competition between the wear and RCF after exceeding a critical slip ratio value. The relationship between wear and RCF can be summarized into two states: RCF-dominant and wear-dominant. Under the RCF dominant state, the rail experienced severe peeling and spalling, leading to fatigue wear. In contrast, under the wear-dominant state, the crack propagation was suppressed due to the continuous removal of surface material and cracks, highlighting the competition between wear and RCF. Based on the competition between wear and RCF, a rail service life diagram was established, which can provide a framework for developing strategies for improving the rail service life.

Wheel idling can cause the formation of white etching layer (WEL) on rails, posing a threat to the safety of train operation. As a tribological phenomenon, the microstructure of rail materials might have different effects on WEL formation behavior. Therefore, the influence of rails with different microstructures (two pearlitic rails and one bainite rail) on the formation mechanism of WEL is studied by using a twin-disk machine tool. The results showed that with the increase in the pearlitic material hardness, the thickness of WELs initially decreased and then increased. For bainitic rail, the parent austenite grain boundaries and bainite microstructure growth were observed during the formation of WELs. The existence of grain boundaries would hinder the development of plastic deformation. During scratching, the pearlite grains had better resistance to dynamic recrystallization and deformation than bainite; as a result, WELs' thickness of pearlitic rails was lower than bainitic rail. The WEL development was a process based on the "thermo-mechanical coupling" mechanism. With the increase in the WEL thickness, the plastic deformation caused by mechanical action would be weakened until it disappeared. After that, the energy for WELs' development downward was from the surface friction heat.

This study investigated the correlation between rail surface hardening behavior and wear/rolling contact fatigue (RCF) damage through a series of rolling contact tests under varying curve radii and axle loads. Three rail steels with different hardness levels were examined: U75VH pearlitic steel (396 HV0.5), 1250B and 1380B bainitic steel (433 and 499 HV0.5, respectively). Results indicated that rail wear increased significantly with decreasing curvature radius or increasing axle load, with a generally slight increase in both crack length and depth. Notably, U75VH with the lowest matrix hardness exhibited the lowest wear rate, while the bainitic rail steel 1250B with intermediate hardness demonstrated the highest wear rate, accompanied by a significant increase in crack length as curvature radius decreased or axle load increased. Further Pearson correlation analysis revealed that wear rate exhibited a more significant negative correlation with post-test rail surface hardness (-0.54, P<0.05), whereas no correlation was observed with matrix hardness (-0.0053), indicating that rail surface hardening behavior played a pivotal role in directly determining wear resistance. The difference in hardening degree was related to the varying microstructural deformation of rail steels. The 1250B with the lowest hardening level was characterized by a discrete granular structure near the surface, in contrast to the fibrous structure seen in U75VH and 1380B rail steels. These findings highlight the importance of considering not only bulk mechanical properties but also surface hardening capability in rail material design.

Rails are subjected to severe corrosion challenges in marine atmospheres. In this study, U75V rail marine atmospheric corrosion behavior and dynamic coupling effects of corrosion on wear and rolling contact fatigue (RCF) were investigated using a marine atmospheric simulation system (NaCl deposition) and a twin-disc rolling contact simulation testing machine. The results indicated that rail marine atmospheric corrosion damage exhibited a typical pitting-dominated characteristic. As exposure time increased, initial discrete pitting coalesced laterally to form continuous corrosion patches, and the corrosion-induced thickness loss followed an exponential growth pattern (exponent n + 1 =1.97>1). Moreover, as the NaCl deposition rate increased, rail corrosion became more severe, and the corrosion-induced thickness loss rapidly increased at first and then slowly, also following an exponential pattern (exponent C=0.5<1). Under rail corrosion and wheel-rail rolling contact alternating conditions, compared to independent corrosion and rolling contact, the increment of rail mass loss accounted for 31 %-42 % of the total wear in the running-in test and 18 %-27 % in the alternating test. This increment was due to the increased local stress concentration and decreased work-hardening capacity caused by the uneven pitting and softened surface material under marine atmospheric corrosion. Also, due to the plastic flow during rolling contact, the micro-cracks embedded with corrosion products were initiated at the bottom of corrosion pitting, and continuous pitting led to surface cracks and material spalling. In addition, the rough rail surface and cracks caused by rolling contact further accelerated both the rate and uniformity of corrosion.

The widespread adoption of tread braking has made it necessary to study the wear and fatigue damage behavior of wheels under the combined action of brake shoes and rails. This study aims to investigate the influence of brake shoe pressure on wheel damage with an innovative small-scale test rig, the 'shoe-wheel-rail contact machine'. Two contact modes were designed: shoe-wheel contact and shoe-wheel-rail contact. The results indicated that, with the increase in brake shoe pressure, both the wear loss of the wheel and braking temperature increased significantly. However, compared to the shoe-wheel contact, the wheel wear and fatigue damage were more severe after the shoe-wheel-rail contact, and they were more sensitive to changes in the brake shoe pressure. Notably, under the shoe-wheel-rail contact, wheel fatigue damage was dominated by sub-surface cracks, whereas almost no fatigue cracks were observed under the shoe-wheel contact. Furthermore, when the braking temperature reaches 350 degrees C, the synergistic effect of the braking temperature and the plastic deformation caused by wheel-rail rolling contact induced the refinement of the microstructure of the wheel material.

Research on factors affecting rolling contact fatigue (RCF) damage of rail materials has become increasingly important since developing effective measures to mitigate RCF damage is crucial. This study focuses on exploring the influence of full slip and partial slip contact modes at the wheel-rail contact patch on the RCF damage behavior and the shakedown limit of the pearlite rail material through wheel-rail RCF rolling-sliding tests. Firstly, based on the wheel-rail adhesion-creep curves in dry, water and oil environments, the creepage required to achieve full slip during the rolling-sliding tests was determined. Then, rolling-sliding tests under full slip contact with different adhesion coefficients were carried out in a dry atmosphere and with the assistance of a third body medium (i.e., oil and water), respectively. Meanwhile, rolling-sliding tests under partial slip contact with the similar contact parameters were performed in a dry atmosphere. The results indicated that RCF damage and wear rates of the rail material under a full slip contact with an adhesion coefficient below the saturation peak on the adhesion-creep curve were significantly less than those under partial slip contact with similar contact parameters. Moreover, under full slip contact with an adhesion coefficient below the saturation peak on the adhesion-creep curve, the pearlite rail materials could exhibit a higher shakedown limit. Furthermore, the influence of full slip and partial slip contact on wheel-rail contact behavior was further analyzed using finite element simulations. Finally, a novel friction modification strategy to mitigate RCF damage and wear of rails was proposed. By applying a specific low-coefficient friction modifier to the wheel-rail interface, the operation of powered wheelsets under controlled creepage conditions that reach the threshold of full slip contact at the wheel-rail contact interface could be employed to achieve the desired adhesion coefficient. Thus, this approach could ensure that the achieved adhesion coefficient met the on-site target adhesion force while reducing RCF damage and wear of rail materials.

Rail materials with different shear yield strengths can exhibit different rolling contact fatigue (RCF) damage response during cyclic contact loading. The objective of this work is to achieve the actual shakedown limits in the shakedown map for rail materials with different shear yield strengths through RCF simulation tests of wheel-rail, and to investigate the relationship between the shear yield strength (ke) and the shakedown limit. Rolling-sliding tests were performed to investigate the RCF damage states of three types of rail materials with different shear yield strengths. Then, according to the differences of RCF damage states for each rail material and the method of nonlinear curve fitting, the actual shakedown limits for three types of rail materials were obtained. The actual shakedown limits for the three types of rail materials were lower than the original one in the classical shakedown map. With an increase in the shear yield strength (ke) of the rail material, the actual shakedown limit is reduced. Moreover, a relationship emerged which allowed a simple method to be proposed to obtain the actual shakedown limit based on the shear yield strength. The changing process and differences in the impact of different shear stress levels on the microstructural damage transformation of rail materials from the perspective of contact mechanics have been discussed. The behavior of severe accumulation of residual stresses during cyclic loading and more likely initiation of microcracks are the main reasons why rail materials with a higher shear yield strength (ke) under great contact loads are more prone to developing RCF crack damages. That is, the shakedown limit for the material with a higher shear yield strength (ke) is much lower. In view of the application of the shakedown map in the evaluation and prediction for RCF damage of rail materials with different shear yield strengths, different shakedown limits should be applied to different rail materials when analyzing their likely performance.

Deformed microstructure and rolling contact fatigue (RCF) cracks are the two predominant damage characteristics of the field wheel and rail materials from the cross-sectional view. The proportion of two damage characteristics varied under different operating conditions. Thus, this study aims to investigate the correlation between material deformed microstructure and RCF crack propagation of U71Mn rail when matching with CL60 wheel using a twin-disc testing machine. An initial deformed microstructure layer on U71Mn rail material was first obtained by testing under dry condition, and then the RCF crack propagation tests were conducted under water condition. Results indicated that when the crack depth was smaller than the initial deformed microstructure layer depth, the deformed orientation dominated the crack propagation direction; when the depth of crack propagation towards the matrix exceeded the depth of newly formed deformed microstructure region, crack propagation direction dominated the microstructure deformed orientation. The increase in the initial deformed microstructure layer depth would intensify both the crack length and depth, and also would result in thicker newly formed deformed microstructure region. The Pearson correlation coefficient between initial deformed microstructure layer depth and crack depth was 0.998. The influence of initial deformed microstructure layer depth on wear rate was slightly greater than crack depth.