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为研究喷丸强化对FGH96粉末高温合金疲劳性能应力集中敏感性的影响,采用不同强度陶瓷丸喷丸强化对合金磨削表面进行了表面处理,并研究了疲劳性能和表面完整性状态。研究结果表明:在650℃下,当应力集中系数由Kt=1提高到Kt=1.7时,FGH96合金磨削状态疲劳极限由583MPa下降到465MPa;经过大强度喷丸强化后,Kt=1.7疲劳极限回复到530MPa;小强度喷丸强化对Kt=1.7疲劳极限无增益作用。大强度喷丸强化消除了加工刀痕,表面粗糙度略有增大,引入了深度达到100μm的残余应力场,在600MPa下疲劳源萌生于次表层,呈单源疲劳模式;小强度喷丸强化无法消除加工刀痕,在600MPa下疲劳源萌生于表层,呈多源疲劳模式。结果证明适宜的喷丸强化工艺可以缓解结构应力集中对粉末合金疲劳性能的削弱。
In order to study the effect of shot peening on the stress concentration sensitivity of the fatigue properties of FGH96 powder superalloys, the surface of the alloy was surface-treated with different strength ceramic shot peening, and the fatigue properties and the surface integrity state were studied. The results show that when the stress concentration factor is increased from Kt = 1 to Kt = 1.7 at 650 ℃, the fatigue limit of FGH96 alloy decreases from 583MPa to 465MPa. After the intense shot peening, Kt = 1.7 fatigue limit Back to 530MPa; small intensity shot peening Kt = 1.7 fatigue limit no gain effect. High-intensity shot peening eliminates the machining marks and slightly increases the surface roughness. A residual stress field of 100 μm in depth was introduced. At 600 MPa, the fatigue source was initiated on the subsurface and presented a single-source fatigue mode. Can not eliminate the processing marks, the source of fatigue in the 600MPa sprout in the surface layer, was multi-source fatigue mode. The results show that proper shot peening can alleviate the weakening of the fatigue properties of the powder alloy by the structural stress concentration.