A comprehensive study of microstructure development and its corresponding tensile properties in nano/ultrafine-grained metastable austenitic steel during accumulative roll bonding (ARB)

作者：Jafarian H R; Anijdan S H Mousavi^*; Eivani A R; Park N

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2017, 703: 196-204.

DOI：10.1016/j.msea.2017.07.050

• Reversed austenite, Severe plastic deformation
• Ultra-fine grains
• Martensite start temperature
• Accumulative roll bonding (ARB)

The evolution of microstructure together with mechanical properties change of Fe-28.5Ni steel, used in design of marine and nuclear related products, processed by different deformation amount during ARB process was elaborated by Electron Backscattered Diffraction (EBSD) method. EBSD results showed that the initial structure of the material contained retained austenite as the main phase besides martensite phase. Martensite phase was diminished after successive ARB cycles due to reduction of martensite start (M-s) temperature. EBSD micro-structural results exhibited that a stabilized nano structure was attained by 6-cycle or 8-cycle of the ARB process with the latter having slightly higher grain size due to the grain growth effect of dynamic restoration mechanism resulting from extreme deformation. Tensile test data on different cycles of ARB processed specimens showed that yield and ultimate tensile strengths were substantially increased after the first cycle of the ARB coinciding with the substantial amount of dislocations in the form of low angle grain boundaries (LAGB). Strengths increased in the successive cycles, though in a much slower pace. Ultra-fine grains were formed instead after high cycles of ARB process. Although such increase in strength generally came at the expense of ductility, the material after 8-cycle had still substantial ductility.

• 出版日期2017-8-4