The Effect of Laser Shock Peening on Back Stress of Additively Manufactured Stainless Steel Parts
The Effect of Laser Shock Peening on Back Stress of Additively Manufactured Stainless Steel Parts
复制标题
激光冲击强化对增材制造不锈钢零件背应力的影响
DOI：
10.1115/1.4056571
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Lawrence Yao, Y.
中科院分区：
文献类型：
--
作者：
Over, Veronica;Donovan, Justin;Lawrence Yao, Y.
这项工作研究了使用激光冲击强化（LSP）来改善增材制造（AM）316 L零件的背应力。由于曲折的微观结构和强烈的纹理，AM金属中不寻常的硬化行为带来了额外的设计挑战。各向异性的机械行为使机械设计的应用变得复杂，因为在相同的负载条件下，3D打印零件的行为与传统制造的零件不同。背应力硬化或Bauschinger效应的普遍存在导致随机载荷下的疲劳寿命降低，并消散了防止裂纹扩展的有益的压缩残余应力。已知LSP通过诱导压缩残余应力来提高疲劳寿命，并且已经被应用于AM金属部件并具有有希望的结果。它在这里表明，LSP也可以被用作一种工具，用于减轻拉伸背应力硬化AM部件，从而减少各向异性硬化行为和改善设计使用。研究还表明，将LSP应用于增材制造部件的方法是实现有效降低背应力的关键。使用滞后拉伸从在XY和XZ方向上构建的增材制造的狗骨样品中提取背应力。测试和比较了LSPed和竣工条件，表明当激光加工沿沿着建造方向施加到样品时，LSPed样品表现出背应力的显著降低。在这些条件下进行的电子背散射衍射（EBSD）阐明了晶粒形态和纹理如何有助于观察到的改善。晶体塑性有限元（CPFE）建模开发的见解，这种减少是通过比较EBSD结果实现的机制。特别是，在确定的晶面和晶粒家族的构建方向上的塑性行为的差异被证明会影响LSP诱导的背应力降低的程度，该程度通过拉伸载荷来维持。
This work studies the use of laser shock peening (LSP) to improve back stress in additively manufactured (AM) 316L parts. Unusual hardening behavior in AM metal due to tortuous microstructure and strong texture poses additional design challenges. Anisotropic mechanical behavior complicates application for mechanical design because 3D printed parts will behave differently than traditionally manufactured parts under the same loading conditions. The prevalence of back-stress hardening or the Bauschinger effect causes reduced fatigue life under random loading and dissipates beneficial compressive residual stresses that prevent crack propagation. LSP is known to improve fatigue life by inducing compressive residual stress and has been applied with promising results to AM metal parts. It is here demonstrated that LSP may also be used as a tool for mitigating tensile back-stress hardening in AM parts, thereby reducing anisotropic hardening behavior and improving design use. It is also shown that the method of application of LSP to additively manufactured parts is key for achieving effective back-stress reduction. Back stress is extracted from additively manufactured dog bone samples built in both XY and XZ directions using hysteresis tensile. Both LSPed and as-built conditions are tested and compared, showing that LSPed samples exhibit a significant reduction to back stress when the laser processing is applied to the sample along the build direction. Electron backscatter diffraction (EBSD) performed under these conditions elucidates how grain morphologies and texture contribute to the observed improvement. Crystal plasticity finite element (CPFE) modeling develops insights as to the mechanisms by which this reduction is achieved in comparison with EBSD results. In particular, the difference in plastic behavior across build orientations of identified crystal planes and grain families are shown to impact the degree of LSP-induced back-stress reduction that is sustained through tensile loading.