长期高温服役乙烯裂解炉管焊接接头损伤分析

摘要

To investigate the damage situation of welding joints of ethylene cracking furnace tubes after long-term service under high temperature,the microstructure,high-temperature endurance property and hardness of welding joints of Cr35Ni45Nb alloy after a six-year service was analyzed.The results show that:after a high temperature and long term service,the primary eutectic carbides in base metal and welding seam of welding joints of Cr35Ni45Nb alloy coarsened and formed a continuous network structure,and the secondary carbides agglomerated together to blocky shape;the carbides of M7C3 and NbC transformed into M23C6 and G phase respectively;the high-temperature endurance property of welding joints decreased and the hardness increased;the area around the fusion line was the weakest zone of the entire welding joints;the damage of the heat affection zone of welding seam of ethylene cracking furnace tubes was comparatively serious after a 6-year service,and the furnace tubes should not be used any more.%为了研究长期高温服役后乙烯裂解炉管焊接接头的损伤情况,对服役6 a(年)后的Cr35Ni45Nb合金焊接接头的显微组织、高温持久性能、硬度等进行了分析.结果表明:经过长期高温服役后,Cr35Ni45Nb合金焊接接头母材及焊缝区域的原始共晶碳化物发生粗化,形成了连续的网状结构,二次碳化物聚集长大成块状;碳化物M7C3和NbC分别转变为M23C6和G相;焊接接头的高温持久性能下降,硬度升高;熔合线附近区域是整个焊接接头的最薄弱区域;该乙烯裂解炉管服役6 a后焊缝热影响区的损伤较为严重,炉管不宜继续使用.