Effects of Nickel Content and Deformation-Induced Martensitic Transformation on the Fatigue Properties of Type 304 Stainless Steel Sheets at Room and Cryogenic Temperatures

摘要

Deformation-induced martensitic transformation on the bending and zero to tension fatigue behavior of Type 304 stainless steel used for the membrane of LNG storage tank at room and cryogenic temperature were investigated. The bending fatigue life at room temperature was decreased at the high level of total strain amplitude. It would be attributed to the crack initiation at γ/α′ interface and the low ductility with the increase of α′ contents. However, at the low level of total strain amplitude, lowering the Ni content increased the bending fatigue life. It was due to the suppression of crack propagation by α′-martensitic transformation around crack tip and the increase of tensile strength. At cryogenic temperature, lowering the Ni content showed beneficial effect on the bending fatigue life due to the increase of slip deformation resistance. In the zero to tension fatigue test, lowering the Ni content showed better fatigue characteristics regardless of the temperature variation. In this case, the hight tensile with the α′-Martensite transformation mostly attests material's life.