焊接热输入对25Cr35NiNb+微合金炉管焊接接头性能的影响

Effects of welding heat input on the properties of 25Cr35NiNb+microalloyed furnace tube welded joint

选用6组焊接热输入对25Cr35NiNb+微合金材质的乙烯裂解炉炉管进行焊接,研究各组焊接热输入对应的焊缝组织和焊接接头高温持久性能。结果表明:在试验温度1050℃、试验应力25 MPa的条件下,焊接热输入为9 kJ/cm、11 kJ/cm时,高温持久断裂时间分别为132 h、119 h;焊接热输入为6、8、12、16 kJ/cm时,高温持久断裂时间分别为78 h、84 h、105 h、109 h;热输入为9~11 kJ/cm的25Cr35NiNb+微合金炉管焊接接头能够获得较长的高温持久断裂时间。微观组织观察发现,不同的焊接热输入下焊缝金属的微观组织形貌存在明显差异,是造成焊接接头的高温持久性能变化的主要原因。

In this paper,six groups of welding heat input were used to weld the 25Cr35NiNb+microalloyed ethylene cracking furnace tubes.The weld structure and high temperature durability of each group of welding heat input were studied.The results show that under the condition of 1050℃and 25 MPa,when the welding heat inputs are 9 kJ/cm and 11 kJ/cm,the high temperature lasting fracture time are 132 h and 119 h respectively.When the welding heat inputs are 6 kJ/cm,8 kJ/cm,12 kJ/cm and 16 kJ/cm,the high temperature lasting fracture time are 78 h,84 h,105 h and 109 h respectively.When the range of welding heat inputs is 9~11 kJ/cm,the 25Cr35NiNb+microalloyed furnace tube welding joint can obtain longer high temperature rupture time.The microstructure observation shows that the microstructure of weld metal is obviously different under different welding heat input,which is the main reason for the change of high temperature durability of welded joint.