激光深熔焊接304不锈钢焊缝成形工艺与控制

Study on Appearance of Weld during Deep-Penetration Laser Welding of 304 Stainless Steel

摘要: 针对高功率激光深熔焊接焊304奥氏体不锈钢缝成形质量差，易形成“钉子头”焊缝特征，研究了焊接速度、离焦量、侧吹保护气喷嘴直径对焊缝几何形貌的影响，同时研究了添加活性硫粉对焊缝熔池的控制作用和对焊缝成型的影响。结果表明：随焊接速度的增加或者随着离焦量由负值变到正值，焊缝深宽比和焊缝上部熔合线与中心线夹角θ均呈现出先增大后减小的趋势，当焊接速度为25 mm/s、离焦量为−3 mm时，焊缝的深宽比和夹角θ值最大，焊缝“钉子头”特征最不明显。在前置45度角侧吹氩气保护时，选择较大的吹气喷嘴直径，可得到深宽比和夹角θ较大值，有效抑制“钉子头”焊缝特征。表面活性元素硫粉的添加，能够实现对焊接熔池的有效控制，减小焊缝表面熔宽、增加焊缝熔深，抑制“钉子头”焊缝的形成。可见优化焊接工艺参数和添加活性粉是控制“钉子头”型焊缝的有效方法。

Abstract: For the reasons that bad weld shapes were easy to form during high-power deep-penetration laser welding, and the “nail-head” weld shape could generated easily, this paper carried out the exper-iments to study the effects of weld speed, defocused distance and jet orifice diameter of shielding gas on the weld seam geometry. The effects of surface-active sulfur powder on weld formation were studied. It was found that when the welding speed increased or the defocused distance changed from negative to positive, the depth-to-width ratio and the angle θ increased first and then decreased. When the welding speed was 25 mm/s and the defocused distance was −3 mm, the depth-to-width ratio and the angle θ were the biggest and the “nail-head” characteristic of weld shape was most non-obvious. During laser welding with argon shielding gas which was set prepo-sition and with 45 degree angle, the relative big jet orifice diameter should be chosen, then the relative big depth-to-width ratio and angle θ could be obtained and the “nail-head” weld shape could be better controlled. The addition of surface-active sulfur powder during laser welding could control the molten pool behavior, reduce the weld width and increase the weld depth, and then the “nail-head” weld shape could be suppressed. Therefore, optimizing welding parameters and adding active powder were two valid means to control “nail-head” weld shape, which could be used during actual production.