Effect of Rolling Temperature on Microstructure Evolution and Mechanical Properties of AISI316LN Austenitic Stainless Steel
School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, Henan, China
Collaborative Innovation Center of Nonferrous Metals, Luoyang 471023, Henan, China
National United Engineering Laboratory for Advanced Bearing Tribology, Henan University of Science and Technology, Luoyang 471023, Henan, China
Nano and Molecular Systems Research Unit, University of Oulu, 90014 Oulu, Finland
School of Mechanical and Automotive Engineering, Anhui Polytechnic University, Wuhu 241000, Anhui, China
Author to whom correspondence should be addressed.
Materials 2018, 11(9), 1557; https://doi.org/10.3390/ma11091557
Received: 10 July 2018 / Revised: 10 August 2018 / Accepted: 12 August 2018 / Published: 29 August 2018
(This article belongs to the Section Structure Analysis and Characterization)
The impacts of rolling temperature on phase transformations and mechanical properties were investigated for AISI 316LN austenitic stainless steel subjected to rolling at cryogenic and room temperatures. The microstructure evolution and the mechanical properties were investigated by means of optical, scanning, and transmission electron microscopy, an X-ray diffractometer, microhardness tester, and tensile testing system. Results showed that strain-induced martensitic transformation occurred at both deformation temperatures, and the martensite volume fraction increased with the deformation. Compared with room temperature rolling, cryorolling substantially enhanced the martensite transformation rate. At 50% deformation, it yielded the same fraction as the room temperature counterpart at 90% strain, while at 70%, it totally transformed the austenite to martensite. The strength and hardness of the stainless steel increased remarkably with the deformation, but the corresponding elongation decreased dramatically. Meanwhile, the tensile fracture morphology changed from a typical ductile rupture to a mixture of ductile and quasi-cleavage fracture. The phase transformation and deformation mechanisms differed at two temperatures, with the martensite deformation contributing to the former, and austenite deformation to the latter. Orientations between the transformed martensite and its parent phase followed the K–S (Kurdjumov–Sachs) relationship.