7B52铝合金叠层复合材料搅拌摩擦焊过程的金属流动

Metal Flow of 7B52 Aluminum Laminated Composite in Process of Friction Stir Welding

7B52铝合金叠层复合材料(7B52 aluminum laminated composite,ALC)是一种新型材料,由两种7XXX系铝合金组成,本文研究了7B52 ALC搅拌摩擦焊接接头的微观组织。研究结果表明:与完整的洋葱环结构不同,7B52ALC搅拌摩擦焊接头仅仅在焊核区前进侧发现了类似洋葱环的鳞片状结构,而焊核区后退侧无明显图案且叠层结构保持完整。鳞片状结构是由洋葱环叠加和材料横向流动形成的横条纹共同组成的。本文提出了一种搅拌摩擦焊金属流动猜想,即焊核区前进侧和后退侧金属流动方式不同,横条纹是由部分向后移动填充搅拌针后方空腔的螺纹内塑性金属组成的。

7B52 aluminum laminated composite(ALC)is a new type of material,which is composed of two kinds of 7XXX aluminum alloys.The microstructure of friction stir welded joint of 7B52 ALC was studied.The research results show that unlike the complete onion ring structure,only scaly structure similar to onion rings is found at the advanced side(AS)of the welding nugget of the friction stir welded joint,while no obvious pattern is shown at the retreating side(RS)and the laminated structure is completely maintained.The scaly structures is proved to be the superposition of onion rings and stripe shapes formed by the transverse flow of materials.A conjecture of the metal flow of friction stir welding is advanced.The conjecture is that the mode of metal flow in AS and RS is different.Additionally,the transverse stripes are formed by a part of plastic metal within the thread filling the cavity behind the stirring pin.