A356Al/TiB_2颗粒增强铝基复合材料的搅拌摩擦焊

Friction Stir Welding of TiB2 Particulate A356 Aluminum Alloy Composite

采用纯机械化的固相连接技术--搅拌摩擦焊成功地焊接了应用原位反应合成法制造的铸态A356Al／6.5％TiB2(体积分数)颗粒增强铝基复合材料,与铝合金相比,铝基复合材料搅拌摩擦焊的焊缝质量对焊接参数更为敏感。该连接方法在较低温度下实现铝基复合材料的焊接,避免了基体铝合金与增强相之间的化学反应,同时在搅拌头机械搅拌、挤压和摩擦热的共同作用下,焊缝区基体材料的晶粒和增强相被破碎并形成再结晶晶核,细化了组织结构,增强相分布也更加弥散。焊缝区的硬度值波动范围很小,抗拉强度比母材增加约20％。研究表明,搅拌摩擦焊用于连接颗粒增强铝基复合材料具有明显的优势。

6.5% TiB2(volume fraction) particulate A356 aluminum alloy composite manufactured by in-situ reaction was successfully joined by friction stir welding (FSW), a kind of pure mechanical solid state joining process. In comparison with un-reinforced Al alloys, the weld quality of aluminum alloy composite is more impressible to FSW parameters. Aluminum alloy composite is welded at lower temperature by FSW process so that the reaction between reinforcement particles and matrix aluminum can be avoided. Meanwhile, because of the combining effect of stirring, colliding and rolling action of rotating pin and friction heat the grains of matrix and reinforcement particles in FSW weld region are partly broken and new recrystallization cores are formed, so the structure becomes smaller and reinforcement particles distribute more uniformly in weld. The hardness of weld region shows less variation than base metal and the ultimate tensile strength of TMAZ is almost 20% improvement. The results show that FSW has obvious superiority in joining of aluminum alloy composite.