2519厚板搅拌摩擦焊缝组织性能及断裂分析

Microstructure-property and fracture behavior of friction-stir welded 2519 aluminium alloy plate

采用搅拌摩擦焊方法对厚度为20 mm的2519高强铝合金板进行了单道对接焊试验,并对焊缝的微观组织、力学性能及断裂特性进行了分析。试验结果表明,在旋转速度为1600 r/min、焊接速度为30 mm/min时,20 mm厚板焊缝的抗拉强度可达313 MPa;厚板焊接时,因焊接速度较慢,厚板焊缝搅拌区的平均显微硬度在115 HV左右,出现了较大程度的软化,其软化区长度约为55 mm;其断裂形式为韧性和脆性的混合型断裂。20 mm厚板焊接时,上下板面搅拌区的温差在150℃左右,热机作用梯度沿板厚急剧变化,是厚板焊接比薄板焊接困难的原因之一。

Friction-stir welding of 2519 high-strength aluminum plate in 20 mm thickness was completed by a single pass.The experiment results demonstrate that when the rotating speed is 1600 r/min and the welding speed is 30 mm/min,the weld's tensile strength reaches 313 MPa.The frictionstir weld softens becouse the welding speed is slow,and the length of the soften zone is 55 mm,and the microhardness in the stir zone is about 115 HV on the average.The fracture mode is ductile and brittle mixed fracture. The temperature difference of the stir zone through thickness is about 150℃.Becouse of the change of temperature and force through thickness,it is very difficult to weld plate when the thickness is large.