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针对发动机用C250钢、TA29钛合金和FGH96粉末合金,开展应力集中系数K_t=1和K_t=1.7条件下疲劳曲线研究,并研究喷丸对应力集中条件下疲劳极限的影响。结果表明:当应力集中系数由K_t=1提高到K_t=1.7时,C250钢、TA29钛合金和FGH96粉末合金的107周次疲劳极限分别从757 MPa,366 MPa和566 MPa降低到526 MPa,240 MPa和465 MPa,说明上述三个高强度合金都存在明显的疲劳极限应力集中敏感性;喷丸强化后,K_t=1.7条件下的疲劳极限提高至597 MPa,297 MPa和530 MPa,说明喷丸有助于从工艺角度缓和高强度合金的疲劳极限应力集中敏感性;随着应力集中系数增加,TA29钛合金和FGH96粉末合金的10~5周次和10~7周次对应疲劳强度差也随之减小,喷丸处理能够使疲劳性能数据的分散性有所降低。
For the engine C250 steel, TA29 titanium alloy and FGH96 powder alloy, the fatigue curve under stress concentration factor K_t = 1 and K_t = 1.7 was studied, and the effect of shot peening on the fatigue limit under stress concentration condition was studied. The results show that when the stress concentration factor is increased from K_t = 1 to K_t = 1.7, the 107th fatigue limit of C250 steel, TA29 titanium alloy and FGH96 powder alloy decreases from 757 MPa, 366 MPa and 566 MPa to 526 MPa, 240 MPa and 465 MPa, respectively, indicating that the above three high-strength alloys have obvious fatigue limit stress concentration sensitivity; after shot peening, the fatigue limit under K_t = 1.7 is increased to 597 MPa, 297 MPa and 530 MPa, Which helps to alleviate the fatigue limit stress concentration sensitivity of high-strength alloys from a technological point of view. With the increase of stress concentration coefficient, the difference of corresponding fatigue strength between 10-5 weeks and 10-7 cycles of TA29 titanium alloy and FGH96 powder alloy also Shot peening reduces the dispersion of fatigue performance data.