焊接速度对高强铝合金搅拌摩擦焊接头组织及力学性能的影响

焊接速度对搅拌摩擦焊接头内焊核区、热机影响区和热影响区组织和晶界沉淀相均有较大的影响。随着焊接速度的提高，焊核区和热影响区内的晶粒尺寸和沉淀颗粒大小、分布密度变化均较大；热机影响区内组织的变形程度变化明显。组织和力学性能综合分析表明，控制焊接速度。获得优良的焊核区组织有利于提高接头的力学性能。性能测试结果表明，焊接速度v=37．5mm／min时，2Al2CZ铝合金接头强度达到最大值(331MPa)。

Effect of welding speed on microstructure and mechanical property of high-strength aluminum alloy friction stir weld

Welding speed has an essential effect on microstructure and precipitations of weld nugget zone, thermal-mechanical zone and heat-affected zone in friction stir weld. As welding speed being increased, there is a considerable change for grain size, precipitation size, distribution and density in weld nugget zone and heat-affected zone; and deformation degree of microstructure in thermal-mechanical zone changes a great. Results show that the microstructure of weld nugget zone plays a leading role in improving mechanical property of joint, which demonstrates that the opportunity exists to manipulate welding speed in order to obtain better microstructure of weld nugget zone and improve joint strength. Mechanical measurement shows that joint has the highest ultimate tensile strength of 331 MPa with welding speed v=37.5 mm/min.