Compressive residual stress (CRS) is induced to delay fatigue crack initiation and prolong fatigue life, in which CRS amplitude and influence depth play an important role, but the traditional mechanical shot peening (MSP) treatment can not further increase the strengthening effect. An innovative thermal vibration MSP (TVMSP) coupling method is proposed to improve the distribution of induced residual stress (RS). Firstly, four strengthening treatments are performed in TA19 titanium alloy by coupling different loads. Subsequently, the gradient RS along the depth, surface morphology and roughness and the microstructure along the depth section are measured and characterized. The experimental results show that the maximum CRS (MCRS) amplitude is increased by 25.43 % and its depth is significantly increased by 100 %. The surface roughness increases slightly due to thermal softening, while the residual iron oxides are shaken off by vibration. The electron back scatter diffraction (EBSD) results indicate that grains are refined, and higher kernel average misorientation (KAM) is aggregated near the surface and deeper positions. Finally, based on these results, the macroscopic mechanical mechanism and microstructure evolution mechanism of RS formation and the formation of surface impact dimple are revealed.

中文翻译：

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一种新型热振动机械喷丸耦合强化方法


诱导残余压应力（CRS）可以延缓疲劳裂纹萌生，延长疲劳寿命，其中CRS幅值和影响深度起着重要作用，但传统的机械喷丸（MSP）处理不能进一步提高强化效果。提出了一种创新的热振动 MSP (TVMSP) 耦合方法来改善诱导残余应力 (RS) 的分布。首先，通过耦合不同载荷对TA19钛合金进行四次强化处理。随后，测量并表征沿深度的梯度RS、表面形貌和粗糙度以及沿深度截面的微观结构。实验结果表明，最大CRS（MCRS）振幅增加了25.43%，深度显着增加了100%。由于热软化，表面粗糙度略有增加，而残留的氧化铁则通过振动抖落。电子背散射衍射（EBSD）结果表明晶粒细化，较高的核平均取向误差（KAM）聚集在表面附近和更深的位置。最后，基于这些结果，揭示了RS形成和表面冲击韧窝形成的宏观力学机制和微观组织演化机制。