In this research, the hot deformation behavior and dynamic recrystallization (DRX) of strategic Nb and V‐bearing high‐Mn steels are investigated. Therefore, the hot compression tests are performed at ...temperature range of 850–1150 °C with temperature interval of 100 °C and strain rates of 0.001, 0.01, 0.1, and 1 s−1. The peak stress, temperature, and strain rate for steels are related by the hyperbolic sine function and the average activation energies for high Mn‐steel, V‐bearing steel and Nb‐bearing steel are obtained 495, 510, and 433 kJ mol−1. The peak stress‐temperature plots show the higher peak stress for Nb bearing steel due to finer initial grains and the presence of NbC precipitates in microstructure. Microstructure results show that DRX as necklace structure is the main mechanism of work softening during process for steels whiles the start of DRX for Nb‐bearing steel is occurred at lower strains than other steels.
In this research, the hot deformation behavior and dynamic recrystallization (DRX) of strategic Nb and V‐bearing high‐Mn steels are investigated at temperature range of 850–1150 °C. Results show that DRX as necklace structure is the main mechanism of work softening during process whiles the start of DRX for Nb‐bearing steel is occurred at lower strains than other steels.
Herein, the Ce‐containing inclusions in8Cr4Mo4V‐bearing steel are taken as the research objective to develop anumerical model of inclusions motions behavior. The model is validated bycomparing it ...with experimental data. During the vacuum arc remelting process, inclusions move along the molten pool's surface toward the edge under theaction of resultant force, and finally become trapped within the mushy zone. Notably, the majority of inclusions are concentrated near the ingot's edge, andtheir numbers decrease as the radial distance decreases. Furthermore, thenumber of Ce‐Mg‐O‐S inclusions exceeds that of Ce‐O‐S inclusions near the ingot's center. This discrepancy arises due to lower density of Ce‐Mg‐O‐Sinclusions, which exhibits a stronger tendency to migrate toward the moltenpool's center. Additionally, as the inclusion diameter increases, buoyancy forceacting on the inclusions increases, resulting in a higher number of inclusionsnear the ingot's center. When considering the effect of gas cooling, theinclusion distribution becomes more pronounced at the ingot's edge. This isattributed to the enhanced cooling capacity of the mold resulting in the decreasing of molten pool depth and consequently a stronger ability of themushy zone to trap inclusions.
The motion behavior of Ce‐containing inclusions in vacuum arcremelting is closely related to the inclusion characteristics. The decrease in density and increase in diameter of inclusions make the net effect of buoyancy and gravity increase, and the inclusions are more likely to escape from mushy zone and exhibit a stronger tendency to migrate toward the molten pool's center.
Microstructures and mechanical properties after spheroidizing annealing (SA) of GCr15 bearing steel with and without an alternating magnetic field (AMF) were investigated. It was found that the ...application of the AMF at the austenitizing stage promoted the dissolution of carbides, accelerated the austenitizing process and increased the hardness of the quenched sample. After isothermal annealing, the carbides in the sample with an AMF more uniformly distributed and became finer in comparison with those without an AMF. The average hardness of the sample treated in the AMF was lower than that without an AMF. The phenomena could be attributed to the enhanced diffusivity in the AMF.
•New method is proposed to determine thermal resistance R in multilayer systems.•The method relies on analyzing thermal response discontinuities at interfaces.•Investigating R in liquid/solid ...interfaces under mechanical loads is feasible.•The method is useful for thermal impedance analysis in multilayer structures.
This study introduces a versatile method for measuring thermal contact resistance in bearing steel with solid–solid and liquid–solid interfaces using lock-in thermography (LIT) technique. The method relies on analyzing the lock-in thermal response across the layers of the bearing structure induced by periodic surface-laser heating. Thermal contact resistance is determined from the discontinuous behavior analysis of the thermal response at the solid–solid or liquid–solid contact interface, based on the resolved heat equation for the multilayered structure. The usability of the method is demonstrated through measurements conducted on a conventional bearing steel configuration, using air and lubricating oil as the interface mediums. Furthermore, the versatility of the method allows for investigating the impact of mechanical load on thermal contact resistance. This proposed approach represents an advanced tool for analyzing thermal contact resistance with applications beyond bearing steel to various multilayered materials. It has the potential to assist in enhancing thermal analysis, improving reliability, extending the lifetime, and reducing maintenance costs of different thermal engineering applications including bearings.
Bearings are the most important component of nearly all mechanical equipment, as they guarantee the steady running of the equipment, which is especially important for high-end equipment such as ...high-speed trains and shield tunneling machines. Requirements regarding the quality of bearings are increasing with the rapid development in technology. A country’s bearings manufacturing level directly reflects the level of that country’s steel metallurgy and machinery manufacturing. The performance of the bearing steel is the critical factor that determines the quality of a bearing. The development of new bearing steel with higher performance is the ambition of material researchers and the expectation of the manufacturing industry. Many famous bearing manufacturing enterprises are competing to develop the new generation of bearing steel. Nanostructured bainitic bearing steel (NBBS), which is a newly developed bearing steel, not only possesses high strength and toughness, but also exhibits excellent wear resistance and rolling contact fatigue (RCF) resistance. In recent years, relevant achievements in NBBS in China have led to significant progress in this field. NBBS was first used in China to manufacture large bearings for wind turbines and heavy-duty bearings, with excellent performance. As a result, NBBS and its corresponding heat-treatment process have been included in the national and industry standards for the first time. The bearing industry considers the exploitation of NBBS to be epoch-making, and has termed this kind of bearing as the second generation of bainitic bearing. In this paper, the development of NBBS is reviewed in detail, including its advantages and disadvantages. Further research directions for NBBS are also proposed.
•The effects of laminar plasma quenching on the microstructure of AISI 52100 bearing steel were studied.•Laminar plasma quenching can refine grains and increase carbon content in martensite to ...enhance mechanical properties.•Laminar plasma quenching can reduce the carbides in the matrix and reduce the self-corrosion current density, and improve the corrosion resistance.
In this work, the effect of laminar plasma quenching on microstructure and corrosion resistance of AISI 52100 bearing steel was studied and its mechanism was discussed. The results indicate that the microstructure of bearing steel material treated by laminar plasma quenching changed from tempered martensite to fine cryptocrystalline martensite, and the quantity of carbide obviously decreased. The average grain size is 746 nm, the carbide content is 3.5 %, and the microhardness is 900 HV0.5. The self-corrosion current density of the treated material is 1.8456 × 10−5 A/cm2 in 3.5 wt% NaCl solution, and it has excellent corrosion resistance. The carbon atoms more easily dissolved into α-Fe to form a supersaturated solid solution due to rapid high-temperature heating and cooling during laminar plasma treatment. The decrease in the amount of carbides after laminar plasma quenching is the cause for the improvement in the corrosion resistance of the bearing steel.
This study aims to obtain key parameters such as the fretting wear coefficient and wear rate of M50 bearing steel through fretting wear experiments. By integrating the Umeshmotion subroutine, a ...validated 3D ball-plane energy dissipation fretting wear model was established. The research explores wear behavior and transition mechanisms under different normal loads and displacement amplitudes. Experimental and finite element analyses show that fretting wear rate is negatively correlated with normal load and positively correlated with displacement amplitude. These variables influence contact stress, shear stress, and slip distance, affecting wear morphology. Results indicate that increasing normal load transitions fretting wear from gross slip to partial slip, while increasing displacement amplitude shifts it from partial slip to gross slip.
To prolong service life of M50 steel for the main shaft bearing, ultrasonic surface rolling process (USRP) was utilized to improve surface performances. The effects of USRP on surface integrity and ...tribological behavior were investigated. The results show the effect of USRP parameters on surface performances follows the order: feed rate > load > rolling times. During the USRP treatment, plastic deformation layer with 24 µm thickness is formed, and fine grain strengthening increases the microhardness (15.56%) and residual stress (79.61%) and decreases the surface roughness (−68.09%), respectively. Friction coefficient and wear rate of USRP sample are lower than those of untreated sample, because USRP helps form a smooth tribolayer and changes the main wear mechanism to slight adhesive wear.
•Ultrasonic surface rolling process (USRP) is used to increase M50 steel service life.•Smooth surface layer with high hardness is formed by plastic deformation.•USRP treatment helps forming a smooth tribolayer and improves friction behavior.•The main wear mechanism changes from adhesive wear to abrasive wear.
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