ABSTRACT Creep deformation, damage and rupture behaviour of 304HCu austenitic stainless steel have been studied at temperatures 923, 973 and 1023 K over the stress range 100–240 MPa. The material exhibited relatively short primary stage of creep deformation followed by secondary (steady-state creep) stage and relatively extensive tertiary stage of creep deformation. The transient creep deformation is analysed based on the Garofalo relationship, The variations of (i) rate of exhaustion of transient creep creep rate and time to onset of secondary creep and (ii) initial creep rate with were found to obey power-law relationship with powers close to unity, thereby facilitating the development of master transient creep curve. The variation of with stress and temperature obeyed Dorn’s equation modified with back stress concept. The time to onset of tertiary creep is found to be proportional to rupture life (tr) while the damage tolerance factor decreased with increase in tr. In view of the prolonged tertiary creep, associated with microstructural change and intergranular creep cavitation, Kachanov–Rabotnov model has been used to assess the creep damage behaviour of the steel. The damage assessment coupled with finite-element analysis closely predicted the creep deformation and rupture life of the steel.

中文翻译：

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304HCu奥氏体不锈钢蠕变变形及损伤行为分析

摘要 研究了 304HCu 奥氏体不锈钢在 923、973 和 1023 K、应力范围 100–240 MPa 下的蠕变变形、损坏和断裂行为。该材料表现出相对较短的初级蠕变变形阶段，然后是次级（稳态蠕变）阶段和相对广泛的蠕变变形三级阶段。基于 Garofalo 关系分析瞬态蠕变变形，发现 (i) 瞬态蠕变速率的耗尽率和二次蠕变开始的时间和 (ii) 初始蠕变速率的变化服从幂律关系功率接近统一，从而促进主瞬态蠕变曲线的发展。随应力和温度的变化服从用背应力概念修正的多恩方程。发现三次蠕变开始的时间与破裂寿命 (tr) 成正比，而损伤容限因子随着 tr 的增加而降低。鉴于与微观结构变化和晶间蠕变空化相关的延长三次蠕变，Kachanov-Rabotnov 模型已被用于评估钢的蠕变损伤行为。损伤评估与有限元分析相结合，可以准确预测钢的蠕变变形和断裂寿命。