采用疲勞性能測試與回歸分析相結(jié)合的方法,研究了S135鉆桿鋼在不同應(yīng)力比下的疲勞裂紋擴(kuò)展行為,獲得了其在穩(wěn)定擴(kuò)展區(qū)和近門檻區(qū)的疲勞裂紋擴(kuò)展速率表達(dá)式,并探討了其疲勞斷裂機(jī)制.結(jié)果表明:隨著應(yīng)力比R的增加,疲勞裂紋擴(kuò)展速率曲線向左上方移動,da/dN增大,△Kth呈線性減小的趨勢;近門檻區(qū)斷口為解理斷裂機(jī)制,穩(wěn)定擴(kuò)展區(qū)斷口以疲勞條帶擴(kuò)展機(jī)制為主,同時也存在解理斷裂.%The fatigue cracks propogation behavior of S135 drill pipe steel at different stress ratios was studied by combining fatigue properites test and data regression analysis methods,the expressions of fatigue cracks propogation rates were obtained in the steady propagation region and near-threshold region,and the fatigue fracture mechanism was discussed.The results show that the increase of stress ratio made fatigue crack propogation rate curves move to the left upper side,da/dN increase,and △Kth decrease in linear.The fracture of near-threshold region was cleavage fracture,and that of steady propogation region was mainly fatigue strip propogation mechanism with cleavage fracture.
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