2219铝合金搅拌摩擦焊焊缝夹杂的形成原因分析与控制

Cause analysis and control of inclusion in 2219 aluminum alloy friction stir weld

在2219铝合金搅拌摩擦焊焊缝中发现月牙状夹杂,通过X射线、光学显微镜、能谱分析研究其分布特征、微观形貌及化学成分,通过试验确定了夹杂形成原因,并分析其形成机理和对接头拉伸性能的影响。结果表明:月牙状夹杂是由诸多异常长大的Al2Cu组成,而Al2Cu的异常长大是由于焊接过程中搅拌头上存在被焊材料的滞留,Al2Cu在高温下发生了粗化,随着焊接的进行,粗化的Al2Cu随机剥落到焊缝中,在搅拌头的作用下形成月牙状夹杂;通过改进搅拌头结构可以避免夹杂。拉伸测试结果表明,夹杂对接头的拉伸性能没有影响。

Crescent-shaped inclusion was found in the friction stir weld of 2219 aluminum alloy,X-ray detection,optical microscopy and energy spectrum analysis were used to study the distribution characteristics,microstructure and chemical composition of inclusions.The cause of inclusion formation was determined by experimental verification.At last,the influence of inclusion formation mechanism and tensile properties on joints was analyzed.The results show that the inclusions were composed of many abnormally grown Al2Cu particles.The abnormal growth of Al2Cu was due to metal material attached at the thread and the groove of friction stir weld tool during the welding process.Al2Cu particles coarsened under high temperature,Al particles were segregated and peeled off into the weld during welding randomly,the separated Al2Cu formed crescent-shaped inclusion under the action of friction stir weld tool.Crescent-shaped inclusions could be avoided by improving friction stir weld tool structure.It was found by tensile test that the inclusion had no effect on the tensile properties of the joint.