在不同摩擦压力下对2A12铝合金进行摩擦焊，采用光学显微镜和电子背散射衍射技术对接头的显微组织进行了分析，并探讨了摩擦压力对接头力学性能的影响。结果表明：焊合区发生了动态再结晶行为，晶粒明显细化，且以大角度晶界为主；接头的抗拉强度随着摩擦压力的增加而先增后降，当摩擦压力为60 MPa时，接头的抗拉强度达到最大（412 MPa）；摩擦焊接头显微硬度在不同摩擦压力下均呈“W”型对称分布，热影响区因强化相S'的转变和粗化而出现软化现象。

2A12 aluminium alloy was welded by the friction welding under different friction pressure. The microstructure of welding zone was analyzed by optical microscopy and electron backscattered diffraction technique. The influence of the friction pressure on the mechanical properties of the joints was discussed. The results show that the dynamic recrystallization occurred in the welding zone, grains were refined and predominantly bounded by high angle boundaries. The tensile strength of joint increased first and then decreased with the increase of friction pressure. When the friction pressure was 60 MPa, the tensile strength was maximum and the value was 412 MPa. The distribution of microhardness all showed "W" type under different friction pressure, and soften behavior appeared in heat affected zone because of the transformation and coarsening of the strengthening phase S'.