Deformation behavior of austenitic stainless steel at deep cryogenic temperatures

• Published in: Journal of nuclear materials 2018-06, Vol.504, p.29-32
• Main Authors: Han, Wentuo, Liu, Yuchen, Wan, Farong, Liu, Pingping, Yi, Xiaoou, Zhan, Qian, Morrall, Daniel, Ohnuki, Somei
• Format: Article
• Language: English
• Subjects: Austenitic stainless steel; Austenitic stainless steels; Austenitic steel; Cryogenic temperature; Defamation; Deformation; Dislocations; Fusion reactors; Low temperature; Martensite; Martensitic stainless steels; Martensitic transformation; Martensitic transformations; Nuclear reactors; Phase transitions; Serrated yielding; Stainless steel; Strain; Stress-induced evolution; Superconductors; Temperature; Twinning
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2018.03.019

The nonmagnetic austenite steels are the jacket materials for low-temperature superconductors of fusion reactors. The present work provides evidences that austenites transform to magnetic martensite when deformation with a high-strain is imposed at 77 K and 4.2 K. The 4.2 K test is characterized by serrated yielding that is related to the specific motion of dislocations and phase transformations. The in-situ transmission electron microscope (TEM) observations in nanoscale reveal that austenites achieve deformation by twinning under low-strain conditions at deep cryogenic temperatures. The generations of twins, martensitic transformations, and serrated yielding are in order of increasing difficulty. •316LN can be martensitic and magnetic when imposing large strains at 4.2 K and 77 K.•The deformation under low strains at low temperatures is achieved by twinning.•The specific serrated yielding at 4.2 K is characterized in detail.•An equation for judging the serration generation is proposed.•In-situ TEM observations of deformations at low temperatures are achieved.