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对航空用5 mm厚的2A12/7075异种铝合金搅拌摩擦焊接头组织及性能进行了研究。结果表明:当旋转速度为1000 r/min,焊速80 mm/min,7075铝合金置于前进侧时,接头焊核区出现了洋葱环,该区域为细小均匀分布的等轴晶组织,晶粒平均尺寸为5.7μm;两侧热影响区晶粒都有所长大,但前进侧热影响区更为明显。整个接头的显微硬度分布呈“W”型,最高硬度值出现在焊核区中心,达146.5 HV0.2,前进侧硬度较回退侧下降明显。接头抗拉强度达到392 MPa,分别是2A12铝合金母材强度的84.5%,是7075母材的71.1%,断裂位置处于前进侧热影响区。
The microstructure and properties of 2A12 / 7075 dissimilar aluminum alloy friction stir welded joint with 5 mm thickness were studied. The results show that when the rotation speed is 1000 r / min, the welding speed is 80 mm / min and the 7075 aluminum alloy is placed on the forward side, an onion ring appears in the weld nugget area, which is a fine and uniform equiaxed grain structure and crystal The average grain size is 5.7μm. The grains in the heat-affected zone on both sides grow up, but the heat affected zone on the advancing side is more obvious. The microhardness distribution of the whole joint showed “W ” type, the highest hardness value appeared in the center of the nugget area, reaching 146.5 HV0.2, and the hardness on the advancing side decreased significantly compared with the retreat side. The joint tensile strength reached 392 MPa, which is respectively 84.5% of 2A12 aluminum alloy base metal strength and 71.1% of 7075 base metal. The fracture location is in the heat-affected zone on the advancing side.