镁合金搅拌摩擦焊接技术

对5mm厚镁合金AZ31B板材的摩擦焊接技术进行了试验研究，结果表明：适合其板材的搅拌摩擦焊接的搅拌头，材料为W6MoSCr4V2高速钢，结构为凹面圆台形，根部直径5．5mm，端部直径为2．5mm，轴肩尺寸为12mm，长度为4．7mm。镁合金搅拌摩擦焊接头的抗拉强度可达母材的90％，延伸率可达母材的50％。搅拌摩擦焊接头焊合区为动态再结晶组织，在接头前进边焊合区与母材有明显的分界线，返回边过渡区有金属微熔的迹象。

Technique of Magnesium Alloy Friction Stir Welding

The experimentation and research of AZ31B magnesium alloy friction stir welding were carried out by using plates of 5 mm in thickness.The results showed that the material suitable for the stir welding head was W6Mo5Cr4V2 high-speed steel.Its structure was in shape of concave round platform,the root of which was 5.5 mm in diameter,the butt 2.5 mm,the shoulder 12 mm,and its length was 4.7 mm.The tensile strength of magnesium alloy friction stir welding joint could be 90% of that of the parent metal,and the specific elongation could be 50% of that of the parent metal.The structure of the weld area was dynamic recrystallization.Apparent boundary existed between the weld area of the forward border joint and the parent metal,while trails of little molten showed in the transitional area of the back border.