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对Q345-R312耐热焊缝进行不同温度的焊后热处理,研究热处理工艺对接头组织及二氧化碳耐腐蚀性能的影响。结果表明,300℃退火后耐热接头焊缝的组织为铁素体和絮状珠光体,絮状珠光体分布均匀,显微硬度增加。600℃热处理后焊缝铁素体呈带状分布,珠光体含量很少,显微硬度降低。热处理后,焊缝和热影响区的自腐蚀电位升高,耐腐蚀性能提高,腐蚀后表面发生点蚀萌生现象,但并未形成明显的腐蚀蚀坑。600℃热处理后,母材的耐腐蚀性能较差,产生蚀坑,形成FeCO_3腐蚀产物。
The post-weld heat treatment of Q345-R312 heat-resistant weld at different temperatures was carried out to study the effect of heat treatment on joint structure and carbon dioxide corrosion resistance. The results show that the microstructure of the welded joint after heat annealing at 300 ℃ is ferrite and flocculent pearlite, the flocculent pearlite is uniformly distributed and the microhardness increases. The weld ferrite shows a ribbon shape after heat treatment at 600 ℃, with little pearlite content and low microhardness. After heat treatment, the self-corrosion potential of the weld and the heat-affected zone increases, and the corrosion resistance increases. After the corrosion, pitting initiation occurs on the surface, but no obvious corrosion pits are formed. After heat treatment at 600 ℃, the corrosion resistance of the base metal is poor, resulting in corrosion pits and the formation of FeCO_3 corrosion products.