The critical challenge in enhancing the fretting fatigue performance of A100 ultra-high strength steel (A100 steel) involved reconciling the conflicting attributes of strength and toughness. In our study, the ultrasonic surface rolling process (USRP) was harnessed to induce gradient nanostructures and a compressive residual stress field on the surface of A100 steel, with the goal of strengthening its wear and fatigue resistance. Through meticulous optimization of USRP parameters over 30 passes, a gradient nanostructure with a substantial depth of approximately 400 μm was successfully formed, while minimizing the martensite lath width on the surface to a mere 44.5 nm. The nanocrystalline mechanism of USRP treatment of A100 steel was the interaction of dislocation proliferation and nailing of nanoscale carbides to form high density low angle grain boundaries and smaller martensitic laths. The introduction of these gradient nanostructures resulted in a notable increase in the depth of the hardened layer and the compressive residual stress field, doubling the original state. Additionally, the fretting fatigue threshold was found to be enhanced by 14.3 %. A factor separation approach revealed that the combined influence of the gradient nanostructure and compressive stress field considerably improved resistance to fretting wear and extended fatigue life. This synergy effectively curbed the nucleation and growth of fretting fatigue cracks, with the compressive residual stress playing a pivotal role in bolstering fretting fatigue resilience.

中文翻译：

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超声表面轧制工艺下纳米梯度纳米组织和压缩残余应力对A100超高强度钢微动疲劳的影响


提高 A100 超高强度钢 （A100 钢） 的微动疲劳性能的关键挑战涉及调和强度和韧性的冲突属性。在我们的研究中，利用超声波表面轧制工艺 （USRP） 在 A100 钢表面诱导梯度纳米结构和压缩残余应力场，以增强其耐磨性和抗疲劳性。通过对 30 次通道的 USRP 参数进行细致的优化，成功形成了具有约 400 μm 深度的梯度纳米结构，同时将表面的马氏体板条宽度最小化到仅 44.5 nm。A100 钢 USRP 处理的纳米晶机制是纳米级碳化物的位错增殖和钉钉相互作用，形成高密度、低角度晶界和更小的马氏体板条。这些梯度纳米结构的引入导致硬化层的深度和压缩残余应力场的显着增加，使原始状态翻了一番。此外，发现微动疲劳阈值提高了 14.3 %。因子分离方法表明，梯度纳米结构和压缩应力场的综合影响显著提高了抗微动磨损能力并延长了疲劳寿命。这种协同作用有效地抑制了微动疲劳裂纹的成核和增长，压缩残余应力在增强微动疲劳弹性方面起着关键作用。