【摘要】 研究了K495合金在700、900℃的高周疲劳性能。测试的疲劳为拉伸疲劳曲线,采用正弦波,应力比R=0.1。结果表明,K495合金在这两个温度下都具有较好的疲劳性能,其疲劳强度极限分别为322、314MPa。在700℃时,当应力较小时,其疲劳裂纹由驻留滑移带在晶界的冲击而产生;当应力较大时,其疲劳裂纹萌生于试样的冶金缺陷处,如凝固缩孔和夹杂物处和一种体心立方结构的富Y相;随最大应力的增加,裂纹源由单一裂纹源向多裂纹源转变;在900℃,裂纹产生于靠近表面的冶金缺陷处。更多还原

【Abstract】 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.更多还原