Sigma phase in tube joints of austenitic heat-resistant steels for ultra supercritical boilers

电站锅炉奥氏体耐热钢管接头中的σ相 Sigma phase in tube joints of austenitic heat-resistant steels for ultra supercritical boilers 孙咸 SUN Xian 1 first-author 太原理工大学焊接材料研究所 太原理工大学焊接材料研究所 Institute of Welding Consumables,Taiyuan University of Technology Institute of Welding Consumables,Taiyuan University of Technology 综述了电站锅炉奥氏体耐热钢管接头中的σ相。结果表明,高温时效后的奥氏体钢接头中析出了形态各异的σ相。σ相的形成条件,一是成分因素,二是温度因素。在σ相形成影响因素中,化学成分的影响十分关键且较为复杂;σ相析出数量随时效温度和时间的增大而增多;热输入过高具有促进σ相析出趋势。试样经历高温蠕变,HAZ粗晶区出现了网状分布的σ相,接头的蠕变断裂强度明显下降。优化焊缝化学成分是控制焊缝中σ相形成的必要条件,而合理的热输入及其工艺措施则是控制接头σ相形成的充分条件。 The sigma phases in tube joints of austenitic heat-resistant steels for power boilers were reviewed. The results show that σ phases with different morphologies were precipi-tated in the austenitic heat-resistant steel joints after high temperature aging. There are two conditions for the formation of the σ phase,one is the composition factor,and the other is the temperature factor. Among the factors influencing the formation of σ phase,the influence of chemical composition is very critical and complex;the amount of σ phase precipitation increases with the increase of aging temperature and time;the excessive heat input has a tendency to promote the precipitation of σ phase.After the sample undergoes high temperature creep,the σ phase with network distribution appears in the HAZ coarse grain region,and the creep fracture strength of the joint is significantly reduced. Optimizing the chemical composition of the weld is the necessary condition to control the formation of σ phase in the weld,and reasonable heat input and its technological measures are the sufficient conditions to control the formation of σ phase in the joints. σ相 管接头 奥氏体耐热钢 电站锅炉 蠕变性能 sigma phase tube joint austenitic heat-resistant steel power boilers creep properties TM621.2 2022-03-08 6 50