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INTRODUCTION

ADIABATIC shear localization (adiabatic shear bands, ASBs) is a common form of localized plastic deformation of material at high strain rate deformation involving the impact loading, such as high-speed impact,[1] cutting,[2] explosive cladding,[3] and fracture.[4] Many researchers have studied microstructural characteristics of shear bands and dynamic deformation in stainless steel. Meyers et al.[5] studied the microstructural characterization of shear localization in an AISI 304L stainless steel and revealed that a unique microstructure formed by rotational dynamic recrystallization. Wang et al.[6] investigated the microstructure and microtexture of the shear band in a 200 series Fe-Cr-Ni austenitic stainless steel and showed that the center of the shear band consists of ultrafine equiaxed grains with diameter 0.1 to 0.3 lm and low dislocation density. Xue et al.[7] investigated the formation mechanisms of nanostructures within adiabatic shear bands

YANG YANG, Professor, is with the School of Material Science and Engineering, Central South University, Changsha 410083, China, and also with the Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China, and also with the National Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China, and also with Key Laboratory of Nonferrous Metals Material Science and Engineering of Ministry of Education, Central South University, Changsha 410083, China. Contact e-mail: [email protected] LIHONG JIANG, Doctoral Student, and SHUHONG LUO, Master Student, are with the School of Material Science and Engineering, Central South University. HAIBO HU and TIEGANG TANG, Researchers, are with the Institute of Fluid Physics, Chinese Academy of Engineering Physics. QINGMING ZHANG, Researcher, is with the State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology. Manuscript submitted November 20, 2015. Article published online August 17, 2016 METALLURGICAL AND MATERIALS TRANSACTIONS A

and proposed that twinning played a critical role in the initiation of nanostructures. Although the formation and microstructural characteristics of shear bands have been extensively reported in stainless steel, little systematic work has been conducted on the susceptibility to shear band formation. Adiabatic shear susceptibility is a standard for evaluating the ability of adiabatic shearing phenomena which appear in materials during dynamic deformation. And the higher adiabatic shear susceptibility of material indicates the higher possibility of adiabatic shearing. The microdefects such as microcracks are more inclined to nuclear within ASBs during the process of dynamic deformation. When microcracks become macrocracks, ASBs may result in significant damage and catastrophic failure of material at high strain rates. Thus, it is very important to investigate the adiabatic shear susceptibility of materials. Adiabatic shear susceptibility is affected by material microstructures and loadin