磁场对工业纯镍激光焊接组织与耐腐蚀性影响

Effect of magnetic field on microstructure and corrosion resistance of industrial pure nickel laser welding

为了研究磁场对激光焊接的影响,采用在焊件上方放置自制的悬挂式永磁体电磁搅拌装置提供横向旋转磁场的方法,对纯镍Ni201薄板进行了CO_2激光堆焊试验。焊后采用金相显微镜和扫描电子显微镜进行观测与分析,并利用电化学工作站对焊接接头进行了电化学腐蚀试验。结果表明,在不同磁场强度下,焊件均能完全焊透,焊缝成形良好,焊缝内部均为粗大的奥氏体柱状晶晶粒组成;磁场强度对激光焊接接头的宏观形貌影响不大;且随着磁场强度的增加,纯镍Ni201激光焊接接头的凝固组织逐渐细化,焊缝耐腐蚀性能逐渐提高;外加横向旋转磁场通过电磁搅拌作用促进熔池的传热和传质,增加过冷度,提高形核率,使晶粒细化,提高焊缝的耐腐蚀性能。该研究为旋转磁场辅助激光焊接技术的工业应用提供了参考数据与技术支持。

In order to study the influence of magnetic field on laser welding,a self-made suspended permanent magnet electromagnetic stirring device was placed above the weldment to provide a transverse rotating magnetic field,and a CO2laser welding test was performed on the pure nickel Ni201thin plate.After welding,metallographic microscope and scanning electron microscope were used for observation and analysis,and electrochemical workstation was used to conduct electrochemical corrosion test of welded joints.The test results show that,the weldments can be completely welded with different magnetic field intensity,and the welds are formed well,and the inside of the weld is composed of coarse austenite grain.The magnetic field intensity has little effect on the macroscopic appearance of laser welded joints.With the increase of magnetic field intensity,the solidification microstructure of pure Ni201laser welded joint is gradually refined,and the corrosion resistance of weld metal is gradually improved.The external rotating magnetic field can promote the heat transfer and mass transfer in the molten pool by electromagnetic stirring,increase the supercooling,increase the nucleation rate,make the grain refined,and improve the corrosion resistance of the weld.