Abstract Welded ferritic steel rotors are a critical dynamic component of fossil-fired power plants. It is essential to investigate residual stress distribution in welded rotors and investigate methods to reduce residual stress for improving structural integrity. In the present study, a creep model that considers back stress is introduced in the residual stress relief simulation of welded ferritic steel rotors in furnace-based uniform post weld heat treatment. Comparisons between the new and Norton–Bailey creep model were conducted numerically, and results indicate that the new creep model can inherit the as-welded residual stress distribution and simulate post weld heat treatment (PWHT) residual stress more accurately, which has been validated with experimental results. Furthermore, it is discovered that the dominant stress relief mechanism of ferritic steel is creep-strain-induced stress relaxation. The creep strain occurred primarily in a short time with a dislocation creep mechanism, and the holding time hardly affected the generation of creep strain. Increasing the PWHT temperature enables more stress relaxation at low temperatures. Additionally, stress relaxation almost no longer occurred when the PWHT temperature exceeded a critical value (approximately 520 °C in this study) that was lower than the recrystallisation temperature. Hence, it is important to control the welded residual stress.

中文翻译：

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考虑焊接转子背应力的蠕变模型应力消除研究

摘要 焊接铁素体钢转子是火力发电厂的关键动力部件。必须研究焊接转子中的残余应力分布，并研究降低残余应力以提高结构完整性的方法。在本研究中，在炉基均匀焊后热处理中焊接铁素体钢转子的残余应力消除模拟中引入了考虑背应力的蠕变模型。对新蠕变模型和 Norton-Bailey 蠕变模型进行了数值比较，结果表明，新蠕变模型可以继承焊后残余应力分布，更准确地模拟焊后热处理 (PWHT) 残余应力，这已得到验证实验结果。此外，发现铁素体钢的主要应力消除机制是蠕变应变引起的应力松弛。蠕变应变主要发生在短时间内，具有位错蠕变机制，保持时间几乎不影响蠕变应变的产生。提高 PWHT 温度可以在低温下实现更多的应力松弛。此外，当焊后热处理温度超过低于再结晶温度的临界值（在本研究中约为 520°C）时，应力松弛几乎不再发生。因此，控制焊接残余应力很重要。提高 PWHT 温度可以在低温下实现更多的应力松弛。此外，当焊后热处理温度超过低于再结晶温度的临界值（在本研究中约为 520°C）时，应力松弛几乎不再发生。因此，控制焊接残余应力很重要。提高 PWHT 温度可以在低温下实现更多的应力松弛。此外，当焊后热处理温度超过低于再结晶温度的临界值（在本研究中约为 520°C）时，应力松弛几乎不再发生。因此，控制焊接残余应力很重要。