Enhanced Mechanical Properties of Nano/Ultrafine-Grained Structure Formed by Martensite Reversion in 18Cr–8Ni Austenitic Stainless Steel
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An NG/UFG austenitic stainless steel of type 18Cr–8Ni austenitic stainless steel was produced by strain-induced martensite phase reversion process. Severe cold deformation (70% reduction) at room temperature was carried out, followed by annealing in the conditions of 710 °C—10 min, 760 °C—5 min, and 950 °C—5 min. The nano/ultrafine grain size obtained was 400 nm, with the yield strength of 878 MPa and high ductility of 33%. The study of the deformation behavior of CG and NG/UFG steels found that the microstructure after ~11% tensile strain of NG/UFG steel included a number of dislocations and deformation twins. In addition, deformation bands and strain-induced martensite were observed in the deformed austenite grain. Whereas after ~11% tensile strain of CG steel, a large number of dislocations, stacking faults, and deformation bands were observed.
KeywordsAustenitic stainless steel Strain-induced martensite Nano/ultrafine-grained structure
The authors gratefully acknowledge support from the National Science Foundation of China (Grant No. 51474064, 51504064, 51234002), National Key Research and Development Program 2016 YFB 0300601, China Postdoctoral Science Foundation 2016M591443, and the Fundamental Research Funds for the Central Universities N160704002, N160708001.
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