In the present investigation, an austenitic AISI 304 stainless steel was subjected to high strain rate surface deformation by Pipe Inner-Surface Grinding (PISG) technique. The depth-dependent deformation parameters (strain, strain rate and strain gradient) were evaluated and the microstructures were systematically characterized. Microstructural evolution from millimeter- to nano-scale was explored, with special attention paid to the localized deformation. Microstructural evolution begins with the formation of planar dislocation arrays and the twin-matrix lamellae, which is followed by the localized deformation characterized by the initiation and the development of shear bands. A twinning-dominated process that was supplemented with dislocation slip-dominated one governed the microstructural evolution inside shear bands. The twin-matrix lamellae transform into extended/lamellar structure and finally the nano-sized grains. Austenitic grains were substantially refined and martensitic transformation was effectively suppressed, of which the underlying mechanisms were analyzed.

在本研究中，奥氏体AISI 304不锈钢通过管道内表面磨削（PISG）技术经受了高应变率表面变形。对与深度有关的变形参数（应变，应变率和应变梯度）进行了评估，并对显微组织进行了系统表征。探索了从毫米级到纳米级的微观结构演变，并特别注意了局部变形。微观结构的演变始于平面位错阵列和双矩阵薄层的形成，然后是局部剪切变形，其特征是剪切带的产生和发展。孪晶为主的过程辅以位错滑移为主的过程控制了剪切带内部的微观结构演变。双矩阵薄层转变为扩展/薄层结构，最后转变为纳米尺寸的晶粒。对奥氏体晶粒进行了实质性的细化，并有效地抑制了马氏体相变，并分析了其潜在机理。