分别在焊缝深度方向、垂直焊接方向、沿焊接方向设置外加磁场后，对15Mn合金钢板进行电子束焊接，研究了外加磁场对电子束焊缝成形、组织及性能的影响。结果表明：不同外加磁场条件下电子束焊缝质量良好，无裂缝、气孔和夹渣等焊接缺陷；磁场方向垂直焊接方向和沿焊接方向时，焊缝在表面和深度方向均发生偏转。与未设置外加磁场相比，磁场方向沿焊缝深度方向时，焊缝的深度和宽度增大；磁场方向沿焊接方向时，焊缝的深度不变，宽度增加，深度方向偏转角较小；磁场方向垂直焊接方向时，焊缝的深度减小，宽度增大，深度方向偏转角较大；焊缝显微组织和截面显微硬度的分布规律不受外加磁场方向的影响。

The electron beam welding of 15Mn alloy steel plate was carried out after the applied magnetic field was set in weld depth direction, perpendicular to welding direction and along welding direction, respectively. The effect of the applied magnetic field on the electron beam weld formation, microstructure and properties was studied. The results show that the electron beam weld quality was good under different applied magnetic field condition, and no crack, porosity and slag welding defects existed. When the magnetic field direction was perpendicular to welding direction or along welding direction, the weld was deflected in both surface and depth direction. Under the condition of magnetic field direction along the weld depth direction, the depth and width of the weld increased, compared with those without applied magnetic field. Under the condition of magnetic field direction along the welding direction, the depth of the weld unchanged, the width increased, and the deflection angle in depth direction was relatively small. Under the condition of magnetic field direction perpendicular to the welding direction, the depth of the weld decreased, the width increased, and the deflection angle in depth direction was relatively large. The weld microstructure and distribution of section microhardness was not affected by the direction of the applied magnetic field.