Abstract:

Through in situ transmission electron microscopy observation on SUS304 metastable austenitic stainless steel during stretching at room temperature, it is found that ε martensite plates were induced preferentially from the sites of dislocation pile-ups. With increasing deformation, some of ε thin martensite platelets disappear and reversibly transform to γ austenite without heating treatment, which is different from the previous result that ε martensite can entirely transform to α′ martensite. Then, some of deformation twins appear and grow along the vertical direction of ε martensite due to\( (111)_{\gamma }\, \bot (10\bar{1}0)_{\varepsilon } \). Moreover, it is directly observed that multiple transformation mechanisms via γ → ε → γ, γ → ε, γ → α′, γ → ε → α′, γ → deformation twins → α′ can co-exist.

Key words: In situ TEM, SUS304 stainless steel, Martensitic transformation, ε Martensite, Deformation twin