Study on High-Cycle Fatigue Behavior of Candidate Stainless Steels for SCWR

The fatigue experiments of commerce stainless steels including 347,316Ti and 310 were conducted under bending and rotating loadings.The environments were at room temperature（RT） as well as at 550℃ in air.The fracture morphology was observed by SEM,and the S-N curves were processed according to the experimental data.The results indicate the fatigue limited stresses for the 3 stainless steels were in the order of 347＜316Ti＜310,which consistent with the order of their tensile strength.Elevated temperature would accelerate the oxidation and therefore the fatigue life would decrease,among them 347 was more sensitive to temperature with the maximum decreasing tendency.All the 3 stainless steels have good resistance to high cycle fatigue when comparing their experimental data with the calculated value from the empirical formula.The fracture morphology presents areas of crack initiation,crack growth and fracture,the width of fatigue ripples is about 1μm,the fracture area has much dimples,and 347 presents much cavities of different sizes in dimples.