45鋼的疲勞裂紋擴(kuò)展速率及其工程構(gòu)件的壽命預(yù)測45鋼的疲勞裂紋擴(kuò)展速率及其工程構(gòu)件的壽命預(yù)測Fatigue Crack Growth Rate of 45 Steel and Fatigue Life Prediction of Its Engineering Components 在常溫下對調(diào)質(zhì)態(tài)和正火態(tài)45鋼緊湊拉伸試樣進(jìn)行了疲勞裂紋擴(kuò)展速率試驗(yàn), 并根據(jù)Paris公式確定了兩種狀態(tài)試樣在穩(wěn)定擴(kuò)展階段的疲勞裂紋擴(kuò)展速率; 分析了含缺陷的45鋼工程構(gòu)件的張開型(I型)裂紋尖端的應(yīng)力強(qiáng)度因子, 然后采用損傷容限設(shè)計(jì)原則, 根據(jù)斷裂力學(xué)試驗(yàn)結(jié)果計(jì)算了構(gòu)件的疲勞裂紋擴(kuò)展壽命, 并進(jìn)行了含缺陷45鋼構(gòu)件的動態(tài)彎曲疲勞試驗(yàn), 以驗(yàn)證理論推算的合理性。結(jié)果表明: 正火態(tài)45鋼的疲勞裂紋擴(kuò)展速率略大于調(diào)質(zhì)態(tài)45鋼的; 采用損傷容限設(shè)計(jì)原則估算的含缺陷45鋼構(gòu)件的疲勞裂紋擴(kuò)展壽命為2.3×106次,與動態(tài)彎曲疲勞試驗(yàn)結(jié)果相吻合。 The fatigue crack growth rate (FCGR) test of 45 steel CT specimens (quenching and tempering condition and normalizing condition) was done at room temperature, and the FCGR equation in the stably expanding stage was determined by Paris formula. The stress intensity factor of open-type (type I) crack tip of 45 steel engineering components with defects was analyzed, and then according to the test results of FCGR and using the design method of damage tolerance, the fatigue lifetime for crack growth was calculated. At the same time, dynamic bending fatigue test on 45 steel components with defects was also done to validate the correctness of theoretical analysis. The results show that the FCGR of normalizing 45 steel was greater than that of quenching and tempering 45 steel. The calculated fatigue lifetime for crack growth of 45 steel components with defects by the design method of damage tolerance was 2.3×106 times, which agreed with the results of dynamic bending fatigue test.
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