Abstract: The service performance of welded parts is directly impacted by the microstructure of the Inconel 718 welded joint； however， there is a lack of comprehensive research on the impact of the Mn element on the microstructure and perfor⁃ mance of the welded junction. In this study， the solid-solution Inconel 718 hot-rolled plates with varied Mn concentrations of <0. 01%，0. 24%， and 0. 34% were joined by using DC pulse arc welding before two stages of thermal aging. The ten⁃ sile test of these plates was performed at room temperature to determine the impact of Mn content on the microstructure and aging mechanical properties of welded joints. The results demonstrate that there are only the Laves phase and no δ phase in the welded joints with three different Mn concentrations. The volume proportion of Laves phase precipitates in the welded joints significantly increases as the Mn content rises from ＜0. 01% to 0. 34%. However， the content of Laves phases decreases slightly， and γ΄΄ begins to precipitate after a two-stage thermal aging treatment. In addition， the tensile strength and elongation of the welded joint are inferior to those of the aged base metal. The tensile properties of the aged welded joints are worsened by the increase in Mn content， causing a decrease in tensile strength from 1 250 MPa to 1 178 MPa and 1 213 MPa， respectively. The three welded joints are broken at the welded areas in the tensile test， all of which are ductile fractures.

Key words: Inconel718 Alloy, Mn Content, Laves Phase, Welding Performance

摘要： 采用w［Mn］＜0. 01%、0. 24%、0. 34%三种不同合金的固溶态Inconel718热轧板材进行直流脉冲电弧焊接， 经双级热时效处理后进行室温拉伸实验，研究 Mn 含量的变化对焊接接头微观组织及时效态力学性能影响规律。 结果表明，三种不同 Mn 含量焊接接头组织中只存在 Laves 相，没有 δ 相析出，随着 w［Mn］由＜0. 01％提高至 0. 34％，焊接接头中Laves相析出体积分数略有增多。经过双级热时效处理后，γ΄΄开始析出，焊接接头组织中Laves 相含量略有减少。与时效态母材拉伸性能相比，焊接接头拉伸强度和伸长率有所降低。且随着Mn含量的增加，时 效态焊接接头拉伸性能略有降低，抗拉强度由 1 250 MPa小幅降低至 1 178 MPa和 1 213 MPa，三种不同 Mn含量的 焊接接头时效态拉伸样品断裂位置皆为焊缝区域，且均为韧性断裂。

关键词: Inconel718合金, Mn含量, Laves相, 焊接性能, 板材