Through-thickness friction stir welding of 3″ thick 7050-T7451 Al alloy was performed as some aerospace applications require welding of thick sections of high strength Al alloys. Detailed microstructural characterization using scanning (SEM) and transmission electron microscopy (TEM), weld hardness mapping and location-specific mini-tensile testing of all weld zones were carried out. Grain boundary precipitates, intra-grain precipitates size and distribution and precipitate-free zones of various zones were characterized using SEM and TEM. Extensive precipitation along grain and sub-grain boundaries and severe precipitate coarsening were common in all weld zones. A minimum hardness of ~77 HV0.3 was registered in the heat-affected-zone region. Strength values from the location specific mini-tensile tests were similar to mapped weld hardness.

进行3英寸厚的7050-T7451铝合金的全厚度摩擦搅拌焊接，因为某些航空航天应用需要焊接高强度铝合金的厚部分。使用扫描（SEM）和透射电子显微镜（TEM）对所有焊接区进行了详细的微观结构表征，焊缝硬度映射和位置特定的微拉伸测试。使用SEM和TEM表征了晶界沉淀物，晶粒内沉淀物的大小和分布以及各个区域的无沉淀物区域。沿晶粒和亚晶粒边界的大量析出和严重的析出物粗化在所有焊接区中都很常见。在热影响区的最低硬度为〜77 HV0.3。特定于位置的微型拉伸试验的强度值类似于映射的焊缝硬度。