基于压焊原理的搅拌摩擦焊匙孔填补技术

A key-hole filling technology for friction stir welding based on the theory of pressure welding

搅拌摩擦焊焊缝尾部匙孔是阻碍搅拌摩擦焊应用推广的主要问题之一,文中提出并研究了一种基于压焊原理的匙孔填补技术.以三相次级整流电阻点焊机为试验平台,2024-T4铝合金3.0mm+3.0mm的搅拌摩擦点焊匙孔为填补对象,具体研究了匙孔填补后各区域的硬度、微观组织及其与塞棒的连接机理.结果表明,引入压焊原理,采用电阻点焊机可以实现匙孔填补,填补后匙孔可分为熔合区、压合区、熔化区及塑性变形区,塞棒与匙孔之间的连接形式以扩散焊接形式为主,局部有熔化焊接形式,且填补过程未对匙孔周围组织及硬度产生明显影响.

The key-hole in the end of friction stir welding (FSW) joint is one of the application and promotion barriers.For overcoming the barrier,a new technology based on the theory of pressure welding for filling key-hole is invented and researched on the three phase secondary rectifier resistance spot welder in the paper.The key-hole in the friction stir spot welding lap joint of 3.0 mm + 3.0 mm thickness 2024-T4 aluminum alloy is filled.In the paper,micro hardness and micro structure about the filled joint are all studied,and the bonding mechanism is analyzed according the welding theory and crystallography.The results prove that the filled joint including the fusion welding zone ,pressure welding zone,plastic deformation zone and melted stopper zone.The diffusion welding is the major metallurgy bond and fusion welding is the minor form of bond between the stopper and key-hole.The micro hardness and structure around the filled key-hole are not changed by the high-efficiency filling technology.