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通过宽载荷水平大子样试验研究了缺陷对粉末冶金镍基高温合金FGH96的疲劳寿命分散性的影响,获得FGH96在宽载荷水平下的疲劳寿命分布特征.通过扫描电镜对疲劳失效断口进行统计分析,揭示缺陷在不同载荷条件下的作用.结果表明:1FGH96中导致疲劳失效的缺陷主要为非金属夹杂;2在高应力水平下(1 200,1 100MPa)下,导致表面萌生裂纹的夹杂是最差疲劳寿命的主导因素,使得疲劳寿命分散性较大;3在中间应力水平(1 000MPa)下,在材料内部萌生裂纹的夹杂并不影响疲劳寿命的分散性;4在低应力水平(900MPa)下,疲劳破坏均萌生于内部,在材料内部夹杂处萌生的裂纹并不影响疲劳寿命的分散性.因此,在高应力水平下的寿命预测需要考虑缺陷信息.
The effect of defects on the fatigue life distribution of powder metallurgy Ni-base superalloy FGH96 was studied by wide-load large-scale test, and the fatigue life distribution of FGH96 under wide load was obtained. The fatigue failure fracture was analyzed by scanning electron microscopy , Revealing the role of defects under different loading conditions.The results show that: 1FGH96 leading to fatigue failure defects are mainly non-metallic inclusions; 2 under high stress levels (1 200,1 100MPa), resulting in surface inclusions crack initiation is the most The dominant factor of poor fatigue life makes the fatigue life more dispersive.3 The inclusions in the material inner sprout crack did not affect the dispersibility of fatigue life under the intermediate stress level (1 000 MPa). 4 At the low stress level (900 MPa) Under the condition of high stress level, the fatigue life is sprouted in the interior, and the crack initiation in the inclusions in the material does not affect the dispersion of fatigue life. Therefore, the prediction of life under high stress level needs to consider the defect information.