6013—T4铝合金薄板搅拌摩擦焊热输入对焊缝成形及组织性能的影响

Effect of friction stir welding heat input on weld appearance and mechanical properties of 6013-T4 Al alloy joint

针对2 mm厚6013—T4铝合金薄板进行了搅拌摩擦焊接工艺试验,用搅拌头旋转速度和焊接速度的比值ω/v表征搅拌摩擦焊的热输入,试验研究了焊接热输入对接头的焊缝成形和力学性能的影响,并分析了接头的显微组织.结果表明,搅拌摩擦焊接头的综合性能较好,抗拉强度和屈服强度分别达到母材的83.3%和75.8%;在不同的搅拌头旋转速度下,随着焊接热输入的增加,接头的屈服强度和抗拉强度降低;ω/v在3 r/mm左右,焊缝成形美观,飞边毛刺少.母材为板条状组织;热影响区晶粒与母材相似,但稍微有粗化;热力影响区的晶粒极不均匀,既有等轴晶,也有拉长的带状组织;焊核区为细小的等轴晶组织.

2 mm Al 6013-T4 alloy thin plates were welded by friction stir welding in experiment,and the ratio of rotating speed of the stir pin to the welding speed ω/v,was used to indicate the friction stir welding heat input.The effect of friction stir welding heat input on the weld appearance and mechanical properties of the joint was studied and the microstructure of the joint was analyzed.The results show that the 6013-T4 Al alloy joint by friction stir welding has the better mechanical properties,the yield strength and tensile strength of the joint can reach up to 75.8% and 83.3%,respectively,ant they decrease with the heat input being increased at the different rotating speed of the stir pin.When the ω/v is 3 round/mm or so,the 6013-T4 Al alloy weld appearance will be good with few flashes.The analysis on the microstructure of the joint shows that the microstructure in the base metal is lath,the microstructure in the heat affected zone is similar to and little larger than that in the base metal.The microstructure in thermal-mechanical affected zone is much coarse and uneven in size,which includes the equiaxed grains and some elongated banded microstructure.In weld nugget zone,the microstructure consists of fine equiaxed grains.