Abstract:

The microstructure changes of TP347 austenitic stainless steel pipe welded joint after 1,050 ℃ solution heat treatment and 900 ℃ stabilization heat treatment are studied. The results show that in the as welded state, the grains in the heat affected zone grow and form different shapes ferrite and precipitate NbC and Cr carbides; after soild solution treatment, the ferrite content in the heat affected zone and fusion zone significantly decreases, and NbC with more dispersed distribution and smaller size is found; after solution treatment followed by stabilization heat treatment, the size of NbC further reduces, indicating that this heat treatment method can effectively disperse Nb carbide particles. Therefore, after solution heat treatment and stabilization heat treatment, TP347 steel undergoes ferrite transformation, NbC formation, and microstructure changes caused by reducing welding thermal cycle, which can effectively improve the material's resistance to intergranular corrosion.

Key words: solid solution, stabilization, heat treatment, TP347 steel, welded joint, microstructure, ferrite content, carbide

摘要：

对TP347钢管道焊接接头在经过1 050℃固溶热处理和900℃稳定化热处理后不同区域显微组织的变化进行了研究。结果表明：在焊态下，热影响区晶粒长大，形成不同形态的铁素体，并有NbC和Cr的碳化物析出；在固溶处理后，观察到热影响区和焊缝区中铁素体含量明显减少，并且发现有分布更分散且尺寸更小的NbC;在先固溶处理再稳定化热处理后，观察到NbC在尺寸上进一步变小，表明这种热处理方法能够有效地分散NbC颗粒。研究结果表明，TP347钢经固溶热处理和稳定化热处理后铁素体转变、NbC形成以及降低焊接热循环引起的显微组织变化，可以有效提高材料的抗晶间腐蚀性能。

关键词: 固溶, 稳定化, 热处理, TP347钢, 焊接接头, 组织, 铁素体含量, 碳化物