High Cycle Fatigue Properties of K495 Superalloy
The high cycle fatigue properties of K495 alloy at 700℃ and 900℃ were investigated.The fatigue curve was tested,the loading cycle was sinusoidal,and the ratio of stress was 0.1.The test results show that K495 has good fatigue properties under those two temperatures,the fatigue limit is 322MPa and 314MPa,respectively.At 700℃,when the stress is low,the fatigue crack initiates from the accumulation of PSB on the grain boundary;when the stress is high,the crack originates from the inner defects of specimen,such as solidification pores,inclusions and a BCC structured Y rich phase.With the increase of maximum stress,the crack origins switch from single point into multiples sites.At 900℃,the crack originates from the inner metallurgical defects near the surface.