6016-T4铝合金与镀锌IF钢搅拌摩擦焊接头的组织与性能

Microstructures and Mechanical Properties of Joints of 6016-T4 Aluminum Alloy/Galvanized IF Steel by Friction Stir Welding

采用搅拌摩擦焊接对1.2 mm厚的6016-T4铝合金和1.0 mm厚的镀锌IF钢进行搭接试验。通过对接头的力学性能和界面组织进行研究,发现在焊接速度为100 mm/min、旋转速度为800～2 000 r/min的条件下焊缝成形良好,表面无沟槽、孔洞等缺陷;当旋转速度为1 200 r/min时,接头的拉剪强度最高,达到172 MPa,为铝合金母材强度的82%;铝合金硬度值呈"W"型分布,最低值在接头两侧的热力影响区及其与热影响区的交界处,硬度最高值在接头的焊核区,达到69.1HV,镀锌IF钢硬度值呈倒"U"型分布,最高值在焊核区,达到192.3HV;在搅拌针和轴肩的共同作用下,铝和钢搭接接头的界面组织特征呈现机械连接+冶金连接的特点,在搅拌针作用区的两侧界面处各形成一个"钩子"状的结构,扎入铝合金基体中,形成机械连接,钢铝界面处生成的Fe-Al金属间化合物、Al-Zn化合物和Fe-Al的层状组织共同形成冶金连接。

The lap welding process of friction stir welding was used on 1.2 mm thick 6016-T4 aluminum alloy and 1.0 mm thick galvanized IF steel.Through the study of the mechanical properties and the interface microstructures of the joint,it was found that the joint formed well under the condition of the welding speed of 100 mm/min and the rotation speed was 800-2 000 r/min,and the surface had no groove,holes and other defects.When the rotation speed was 1 200 r/min,the shear strength of the joint reached 172 MPa,which was 82%for the strength of aluminum alloy.The hardness value of aluminum alloy was“W”type distribution and the lowest hardness of the aluminum alloy was at the junction of the thermo-mechanically affected zone and the heat-affected zone,the highest hardness in the weld nugget area was 69.1HV.The hardness value of galvanized IF steel was“U”type distribution and the highest hardness in the weld nugget area of the galvanized IF steel was 192.3HV;Under the influence of the pin and the shoulder,the interface of aluminum and steel lap joints presented the characteristics of mechanical connection and metallurgical connection;“Hook”structures were formed at the two sides of the pin zone,which was inserted into the aluminum alloy matrix to form a mechanical connection,Fe-Al intermetallic compounds,Al-Zn compounds and Fe-Al layers in the steel and aluminum interface form metallurgical connections.