管式加热炉用TP347H与P5炉管异种钢GTAW焊接工艺研究

Research on GTAW Welding Technology for the Dissimilar Steels TP347H and P5 Furnace Tubes in Tubular Heaters

针对ASME SA312 TP347H奥氏体不锈钢管与ASTM SA335 P5铁素体耐热钢管的异种钢焊接存在金属稀释、碳迁移和残余应力等问题,在考虑稀释影响的基础上,选择ER309和ERNiCr-3两种焊接材料根据是否焊后热处理以及是否堆焊隔离层制定了6种焊接工艺方案,并通过焊接试验、力学性能试验和金相检验,对比分析了不同工艺下焊接接头的性能。结果表明:外观检查和RT结果均符合相关标准要求;所有试件的抗拉强度均达到标准规定的415 MPa以上,其中最大值达到505 MPa,且断后伸长率在25%以上,TP347H侧热影响区的冲击吸收功平均值为54.0~70.5 J,均满足标准规定;直接焊接法未经焊后热处理的焊接接头P5侧母材热影响区附近硬度超标,而经焊后热处理的焊接接头硬度值均满足标准要求;经焊后热处理的焊接接头碳扩散更明显,而采用ERNiCr-3焊丝进行堆焊隔离层,并进行后热处理的焊接接头碳扩散程度最小。综合分析,ERNiCr-3堆焊隔离层+后热工艺方案得到的焊接接头性能最佳,满足标准要求,且无需进行焊后热处理,更适合现场焊接。

Welding between ASME SA312 TP347H austenitic stainless steel pipes and ASTM SA335 P5 ferritic heatresistant steel pipes presents challenges such as metal dilution,carbon migration,and residual stress.Considering the impact of dilution,two welding materials,ER309 and ERNiCr-3,were selected to create six welding procedure specifications based on whether post-weld heat treatment(PWHT)was applied and whether a cladding layer was welded.These specifications were tested through welding experiments,mechanical property tests,and metallographic examination to analyze the performance of welded joints under different procedures.The results show that the appearance inspection and RT results meet the relevant standards.The tensile strength of all specimens exceeds the standard requirement of 415 MPa,with a maximum reaching 505 MPa,and the elongation after fracture is above 25%,fulfilling the standard requirements.Impact test results also meet the standard requirements,with the average impact absorbed energy of the TP347H side heat-affected zone ranging from 54.0 to 70.5 J.The hardness near the P5 side base metal heat-affected zone of the welded joint without PWHT exceeds the standard in the direct welding method,while the hardness values of welded joints with PWHT meet the standard requirements.Carbon diffusion is more pronounced in welded joints with PWHT,while the least carbon diffusion occurs in welded joints that use ERNiCr-3 welding wire for cladding and undergo post-weld heat treatment.Based on the comprehensive results,the welding joint performance is optimal with the ERNiCr-3 cladding layer and post-weld heat treatment process,meeting the standard requirements without the need for PWHT,making it more suitable for on-site welding.