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对BSTMUF601合金在不同温度和应力条件下进行了拉伸蠕变实验,获得了该合金的高温蠕变的变形规律,基于此提出了一种新的修正q映射法蠕变本构模型,该模型考虑了蠕变3阶段的蠕变特点.模型预测结果与实验结果吻合较好,平均相对误差为1.86%,相对于没有考虑第2阶段的θ映射法模型和没有考虑第1阶段的修正q映射法模型相对误差分别减少0.10%和6.02%,表明该模型具有较强的适用性,且不降低预测精度.对蠕变和蠕变断裂试样的位错组态和空洞演化进行了显微分析,结果表明,稳态蠕变阶段蠕变应力指数都接近5,合金主要通过位错攀移越过γ′相的方式变形,并未观察到层错和微孪晶存在于γ′相或基体中,蠕变变形机制主要是位错攀移.空洞在晶界上形核,长大连接形成裂纹,在应力集中作用下,裂纹沿晶界扩展,最终导致断裂,蠕变断裂机制主要是晶界断裂.
The tensile creep experiment of BSTMUF601 alloy under different temperature and stress conditions was carried out, and the deformation law of high temperature creep of the alloy was obtained. Based on this, a new modified q-mapping creep constitutive model was proposed. The model Considering the creep characteristics of creep stage 3, the model predictions agree well with the experimental results, with an average relative error of 1.86%. Compared with the θ mapping model without considering the second stage and the modified q map without considering the first stage, The relative error of the law model is reduced by 0.10% and 6.02% respectively, which shows that the model has strong applicability and does not reduce the prediction accuracy. The dislocation configuration and the cavity evolution of creep and creep rupture samples are analyzed microscopically The results show that the creep stress exponents are all close to 5 in the steady-state creep phase, and the deformation of the alloy mainly crosses the γ ’phase through dislocation climbing. No stacking faults and micro-twins are observed in the γ’ phase or the matrix , The mechanism of creep deformation is mainly dislocation climbing.The voids nucleate on the grain boundaries and grow up and connect to form cracks. Under stress concentration, the cracks expand along the grain boundaries and eventually lead to the fracture. The mechanism of creep and fracture is mainly the grain boundaries fracture.