FGH97高温合金不同控制模式低周疲劳性能研究

Study on the Low Cycle Fatigue Properties of an FGH97 P/M Superalloy with different test control modes

摘要:

研究了氩气雾化制粉+热等静压+热处理的全尺寸FGH97合金盘件不同位置组织、650℃拉伸性能、应力和应变控制方式低周疲劳性能及其断口形貌，结果表明：盘件不同位置晶粒度、γ′相尺寸形貌相似，650℃抗拉强度在1325-1340MPa间，650℃屈服强度1010-1025MPa。应力控制低周疲劳寿命（Nf）均值约200000周次，Weibull分布尺度因子η=215194，尺寸＜80μm的夹杂物对Nf影响不明显。应变控制Nf＜20000周次时，η=14622，Nf＞20000周次时，η=44342；夹杂物面积变化引起Nf值Weibull分布特征值β不同。两种控制方式下，疲劳断口裂纹源都主要由夹杂物引起，断口形貌无明显差异。应变控制对夹杂物更敏感。

Abstract:

The low cycle fatigue properties with Stress and Strain constant-ampitude controlled test methods，the tensile properties at 650℃, the microstructure at different positions and the fatigue fracture of an FGH97 superalloy disc, which was manufactured by Argon Atomization (AA) + Hot Isostatic Pressing (HIP)+Heat Treatment process, were investigated. The results reveal that the grains size and the γ′ weresimilar at different positions. The tensile strengthes at 650℃ were between 1325 to 1340MPa, and the Yield Strengthes were between 1010 to 1025MPa, which are relatively stable. The average Nf by Stress-controled was 200000 cycles at different positions, Weibull distribution η was 215194.The effect of the inclusion size of less than 80μm on Nf was not obvious. The Weibull distribution η of the Strain-controled was 14622 when the Nf was less than 20000 cycles, and 44342 when Nf was more than 20000 cycles. The variation of inclusion area leads to the difference of characteristic value beta of Nf Weibull distribution. The crack source of fatigue fracture was mainly the inclusions, and the fracture morphologies were rather similar. The fatigue by the strain controled test was more sensitive to the inclusions.