High-cycle fatigue behavior of nickel-base single crystal superalloy
(1.Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China2.Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China3.Department of Superalloys, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110016, China)
Abstract: High-cycle rotating bending fatigue behavior of SRR99 nickel-base single crystal alloy at 700 and 900℃ was investigated. The fatigue strengths for 107 cycles are 350 and 335MPa at 700 and 900℃, respectively. The total fatigue life becomes shorter when the temperature increases regardless of the loading stress and frequency. With the number of cycles decreasing, the difference in fatigue strength at the two temperatures becomes smaller. Typical fatigue rupture process including crack initiation site, crack propagation region and final rupture region exhibits at 700℃. The fracture surface is basically characterized by cleavage rupture at 900℃.
Key words: single crystal superalloy； high-cycle fatigue； fatigue limit stress