A356-T6/6061-T6异种铝合金搅拌摩擦焊的工艺研究

通过对6 mm厚的A356-T6/6061-T6异种铝合金的搅拌摩擦焊工艺试验研究,采用OM、SEM、万能拉伸试验机、显微硬度仪等分析了母材位置、焊接速度对接头组织和性能的影响。研究结果表明:当旋转速度为1 000 r/min、焊接速度为100~400 mm/min时,均可获得内部无明显缺陷、外观良好的异种铝合金接头;A356-T6铝合金置于前进侧时有利于材料的迁移,焊缝区组织由典型的焊核区、热机械影响区和热影响区特征组织组成,焊核区域晶粒由表层向底层逐渐细化;接头拉伸性能随焊接速度的增加而增大;焊接速度较低时,A356合金位于前进侧有利于获得强度更高的接头,而焊接速度较高时,6061位于前进侧有利于获得高性能接头,且接头的屈服强度和延伸率均较A356位于前进侧时高;无论A356还是6061置于前进侧,接头的断裂位置均位于A356侧热影响区,与母材放置位置无关,这与焊缝硬度最小值区位置相吻合。

Study on The FSW Process of A356-T6/6061-T6 Dissimilar Aluminum Alloy

The friction stir welding process of 6 mm A356-T6 and 6061-T6 dissimilar aluminum alloy were study. And the joint organization and performance affects on welding speed and base metal position were investigated by using OM, SEM, universal tensile testing and micro hardness testing.The results show that no obvious defects and good appearance dissimilar aluminum joints could be acquire when the rotational speed of 1 000 r/min, welding speed about 100 to 400 mm/min were used. The material migration increased with welding speed decreasing, and A356 -T6 aluminum which located in advancing side was beneficial to transport materials. The joint consisted of nugget zone, thermal mechanical affected zone and heat affected zone,which are typical characterized organizations in FSW joints. The grain of weld nugget refined from surface to the bottom gradually. The tensile properties of the joints were increased with the welding speed increases. A356 alloy in the advancing side could be obtain higher strength joints at low welding speed, while higher strength were obtained at higher welding speed when 6061 in the advancing side. However,the yield strength and elongation of joint when A356 located in advancing side were higher than 6061 located in the advancing side. The fracture location of joints located in the heat affected zone of A356 side regardless of which base metal located in advancing side, and had nothing to the base metal location. And the hardness test exhibited that fracture location of joints correspond to the zone of the lowest hardness value.