服役HPM S-C合金炉管焊接接头研究

Study on welding joint of serving HPM S-C alloy furnace tubes

HPM S-C合金炉管具有耐高温、耐腐蚀、抗渗碳和抗蠕变等特点。对比研究该炉管在乙烯裂解炉辐射段服役前后组织的性能变化,重点分析背面充氩气保护小线能量TIG焊焊接新炉管与新炉管、服役炉管与新炉管、服役炉管与服役炉管的焊接接头的金相组织、拉伸性能、弯曲性能和冲击性能。结果表明,服役后的HPM S-C合金炉管内壁存在渗碳,晶界析出大量脆性相,塑形指标显著降低,焊接接头热影响区的粗晶脆化进一步恶化了合金的变形能力。

HPM S-C alloy furnace tube has high temperalure resistance,corrosion resistanee,carburizing and creep resistance.In this paper,microstructure and performanee of tube used for radiant section were studied before and after service in ethylene cracking furuaee.Comparative perfurmances of three weht joint （joint between new fumace tubes,joint between new tube and furnace tube after service,joint between furnace tubes in service） wehted by TIG process with less heat input and back argon protection were made by metallographie examination,tensile test,bend lest and impact lest.The results show that the inner wall of HPM S-C alloy furnace tube after service exists carburized layer.grain buuudary precipitation of brittle phase,deformability degradation significantly.Coarse- grained brittle microstuucture in heat affected zone of the weld joint may further deteriorate the deformation ability of the alloy.