【摘要】 喷丸残余压应力能有效提高材料的抗疲劳性能，但服役过程中残余压应力不稳定，会出现松弛。为深入研究喷丸残余压应力的松弛规律，对喷丸2024铝合金标准拉伸试样在两种拉伸载荷强度下进行疲劳试验研究，采用基于cosα法的μ-X360n型X射线衍射仪分析了残余应力在疲劳过程中的变化规律。结果表明：在载荷10 kN时，残余压应力出现了常规松弛，即在首次循环加载后残余压应力大幅度下降，在剩余的疲劳加载过程中，残余压应力基本保持不变或缓慢下降，且引入的残余应力分布始终同初始分布保持一致；在载荷15 kN时，残余压应力出现了反向松弛，即在首次循环加载后残余压应力变为残余拉应力，残余应力分布由初始的“√”型分布变为了近似于一条直线分布，由内向外逐渐减小。为描述喷丸残余压应力的松弛行为及过程，在已有试验模型基础上，提出了考虑喷丸表面状态的残余应力松弛模型。更多还原

【Abstract】 The residual compressive stress of shot peening can effectively improve the fatigue resistance of the material, but the residual compressive stress is unstable during service and will relax. In order to further study the relaxation rule of the residual compressive stress, the fatigue test of the standard tensile specimen of the shot peening 2024 aluminum alloy under two kinds of load was carried out. μ-X360 n X-ray diffractometer based on cosα method was used to analyze the variation law of residual stress during fatigue test. The results show that when the load is 10 kN the residual compressive stress shows regular relaxation, that is, the residual compressive stress drops significantly after the first cycle loading and the residual compressive stress basically remains unchanged or slowly decreased. At the load of 15 kN, the residual compressive stress appears to relax in reverse, that is, the residual compressive stress becomes a residual tensile stress after the first cyclic loading, and gradually decreases with the number of fatigue cycles and the residual stress distribution changed from the initial “√”-shaped distribution to an approximate linear distribution, gradually decreasing from the inside to the outside. In order to describe the relaxation behavior and process of residual compressive stress of shot peening, based on the existing experimental models, a new residual stress relaxation model considering the surface state of shot peening was proposed.更多还原