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<p>To systematically investigate the effects of ultrasonic surface rolling process (USRP) on the surface integrity and fatigue properties of 20CrNiMo carburised steel, a three-dimensional model of USRP was constructed based on a combination of finite element simulation and experimental validation, revealing the mechanism of ultrasonic amplitude, static load and other parameters on the distribution of residual stresses and plastic deformation behaviour. The results show that the residual compressive stress value of the surface layer increases with the optimization of processing parameters due to the USRP treatment, and the maximum residual compressive stress is located on the subsurface, and the simulation and experimental errors of multi-pass processing are controlled within 5%, which verifies the reliability of the model. Through the orthogonal experimental design combined with grey correlation analysis and principal component analysis, the optimized parameter combinations were obtained: static load of 1400 N, ultrasonic amplitude of 6&#xa0;μm, rolling passes: 6, and step distance of 0.05&#xa0;mm. Under these parameters, the surface microhardness was increased by 8.7% to 751.3 HV<sub>0.5</sub>, roughness was reduced by 34% to 0.29&#xa0;μm, grain size was refined by 11% to 0.81&#xa0;μm, the ratio of small. The proportion of angular grain boundaries increased, and the KAM value increased from 1.60° to 1.99°, indicating a significant increase in dislocation density. USRP did not change the phase composition of the material, but the martensitic microstructure was converged through intense plastic deformation, forming a gradient nanostructure. Corrosion resistance tests showed that the corrosion potential was positively shifted and the corrosion tendency was reduced after USRP treatment. Rotational bending fatigue experiments show that the median fatigue life of the specimen with optimal parameters reaches 18,503 cycles, which is 268% higher than the original specimen. The fatigue crack source is shifted from the surface to the subsurface layer, which is attributed to the synergistic effect of the reduction of surface roughness, the introduction of residual compressive stresses and grain refinement. The study confirms that at a static load of 1000 N, the improved corrosion resistance effect of surface quality enhancement counteracts the negative impact of increased geometric dislocation density.</p>

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Ultrasonic Surface Rolling Process with Multi-Parameter Coupling for Surface Integrity and Fatigue Life Enhancement of 20CrNiMo Steel

  • 期刊论文

  • 发表日期：

    2025年10月10日

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  • Shubo Xu,
  • Yanrui Wang,
  • Kangwei Sun,
  • Hongliang Zhou,
  • Yuefei Pan,
  • Xiaojuan Lin,
  • Tingting Li,
  • Tianhua Li,
  • Chen Xu,
  • Wei Zheng,
  • Lili Huang

摘要

To systematically investigate the effects of ultrasonic surface rolling process (USRP) on the surface integrity and fatigue properties of 20CrNiMo carburised steel, a three-dimensional model of USRP was constructed based on a combination of finite element simulation and experimental validation, revealing the mechanism of ultrasonic amplitude, static load and other parameters on the distribution of residual stresses and plastic deformation behaviour. The results show that the residual compressive stress value of the surface layer increases with the optimization of processing parameters due to the USRP treatment, and the maximum residual compressive stress is located on the subsurface, and the simulation and experimental errors of multi-pass processing are controlled within 5%, which verifies the reliability of the model. Through the orthogonal experimental design combined with grey correlation analysis and principal component analysis, the optimized parameter combinations were obtained: static load of 1400 N, ultrasonic amplitude of 6 μm, rolling passes: 6, and step distance of 0.05 mm. Under these parameters, the surface microhardness was increased by 8.7% to 751.3 HV0.5, roughness was reduced by 34% to 0.29 μm, grain size was refined by 11% to 0.81 μm, the ratio of small. The proportion of angular grain boundaries increased, and the KAM value increased from 1.60° to 1.99°, indicating a significant increase in dislocation density. USRP did not change the phase composition of the material, but the martensitic microstructure was converged through intense plastic deformation, forming a gradient nanostructure. Corrosion resistance tests showed that the corrosion potential was positively shifted and the corrosion tendency was reduced after USRP treatment. Rotational bending fatigue experiments show that the median fatigue life of the specimen with optimal parameters reaches 18,503 cycles, which is 268% higher than the original specimen. The fatigue crack source is shifted from the surface to the subsurface layer, which is attributed to the synergistic effect of the reduction of surface roughness, the introduction of residual compressive stresses and grain refinement. The study confirms that at a static load of 1000 N, the improved corrosion resistance effect of surface quality enhancement counteracts the negative impact of increased geometric dislocation density.