9Cr钢/Inconel 625镍基合金异种接头激光窄间隙焊接工艺研究

Research on Narrow Gap Laser Welding of Dissimilar Joint Between Nickel-Based Inconel 625 and 9Cr Steel

采用窄间隙激光填丝焊接技术实现了25mm厚度9Cr钢/Inconel 625镍基合金异种材料的连接,并对所获得的焊接接头组织和力学性能进行测试分析。结果表明:焊接接头在保持窄焊缝(宽度约4.5mm)条件下,有效避免了侧壁未熔合等缺陷,焊缝成形良好。焊接接头组织显示出典型的树枝晶形貌特征,其间距和生长方向受到焊接热循环的影响。硬度试验表明,9Cr钢一侧热影响区硬度达到450HV,高于Inconel 625镍基合金母材(205HV)、9Cr钢母材(215HV)及焊缝区(220HV)。焊接接头的室温抗拉强度为468MPa,断裂位置位于Inconel 625母材上。焊接接头焊缝区室温冲击功为68J,低于Inconel 625合金(105J),高于9Cr钢(49J)。本研究可为9Cr钢与镍基合金厚壁材料激光窄间隙焊接提供参考。

Dissimilar joint welding between nickel-based Inconel 625 and 9Cr steel on 25 mm thick plates were executed using the narrow gap laser welding with filler wire, then microstructures and the mechanical properties of different zones of joints were tested and analyzed. The results showed that the joint had sound appearance with narrow weld gap（about 4. 5mm）, as a result, side wall incomplete fusion was avoided. The mierostrueture of welded joint indicated typical dendritic morphology, and dendrite spacing and growth direction was affected by thermal cycle. The result of hardness test demonstrated that the hardness of heat affected zone （HAZ） in 9Cr steel reached 450 HV, higher than the hardness of the nickel-based Inconel 625 base（205 HV）, the 9Cr steel base（215 HV） and welded zone（220 HV）. The tensile strength of joint at room temperature achieved 468 MPa, and the fractures occurred in the Ineone1625 base. The impact energy of welded zone at room temperature achieved 68 J, lower than that of nickel-based Inconel 625 base（105 J）, but higher than that of 9Cr（49 J）. The study can provide reference for narrow gap laser welding on thick wall between 9Cr steel and nickel-based alloy.