为改善激光立体成形GH4169镍基高温合金的组织和力学性能,将旋转磁场引入到激光立体成形系统中,进行了不同磁场强度下GH4169镍基高温合金的激光立体成形,分析了电磁场对沉积态试样显微组织和硬度的影响。结果表明: 电磁搅拌激光立体成形GH4169合金仍具有外延连续生长粗大柱状晶特征,组织致密,无冶金缺陷;在一定范围内,随着磁场强度的增加,沉积态组织中枝晶间共晶Laves 相呈减少趋势,且其相形貌由不规则蠕虫状变为颗粒状;枝晶间合金元素微观偏析程度也逐渐减弱。显微硬度测试结果显示随着磁场强度的增加材料硬度有所提高。以上分析表明,电磁搅拌引起的激光立体成形熔池中液态金属的强烈对流对材料显微组织有影响。

In order to improve the microstructure and mechanical properties of GH4169 superalloy fabricated by laser solid forming (LSF), rotating magnetic field is introduced to LSF processing. The microstructurs of LSF GH4169 superalloy with different magnetic field parameters have been investigated and the microhardness of the as-deposited samples was tested. The results show that the microstructure of GH4169 superalloy fabricated by electromagnetic stirring assisted laser solid forming (EMS+LSF) still possesses the feature of coarse dendrites, which growing epitaxially along the deposition direction, and the microstructure is dense without any significant metallurgical defect. Meanwhile, with the increasing of magnetic field intensity in a certain range, the amount of Laves eutectic phase formed in interdendritic area decreases, and the morphology of Laves eutectic phase changes from irregular vermicular shape to granular shape. The element micro-segregation becomes weaker. Furthermore, the results of hardness test show that the microhardness of that material is somewhat increased with the increasing of magnetic field. The above analysis indicates that EMS has an influence on the microstructure of LSF GH4169 alloy through the strong convection of liquid metal in laser molten pool.