BSTMUF601合金的高温蠕变变形机制

发布时间：2018-05-16 12:32

本文选题：BSTMUF合金 + 蠕变变形　；参考：《金属学报》2015年03期

【摘要】：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.
[Abstract]:Tensile creep experiments of BSTMUF601 alloy at different temperatures and stresses were carried out, and the deformation law of creep at high temperature was obtained. Based on this, a new creep constitutive model of modified q-mapping method was proposed. This model takes into account the creep characteristics of three stages of creep. The model prediction results are in good agreement with the experimental results. The average relative error is 1.86, which is 0.10% and 6.02% less than that of the 胃 mapping model without considering the second stage and the modified Q mapping model without considering the first stage, respectively, which indicates that the model has strong applicability. And the prediction accuracy is not reduced. The dislocation configuration and cavity evolution of creep and creep fracture specimens are analyzed microscopically. The results show that the creep stress exponents are close to 5 in the steady state creep stage, and the alloy is deformed mainly by dislocation climbing over 纬 'phase. No stacking faults and micro-twins were observed in 纬 'phase or matrix, and the creep deformation mechanism was mainly dislocation climbing. The cavities nucleate at grain boundaries and form cracks at long and large joints. Under the action of stress concentration, the cracks propagate along grain boundaries and eventually lead to fracture, and the creep fracture mechanism is mainly grain boundary fracture.
【作者单位】：北京科技大学机械工程学院;宁波宝新不锈钢有限公司;宝山钢铁有限公司特殊钢事业部;
【基金】：国家自然科学基金项目50831008和51105029 国家科技重大专项项目2014ZX04014-51资助~~
【分类号】：TG132.3

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