搅拌摩擦焊对接面附近材料流变行为研究

Research on the material flow and strain behavior near the initial butt surface in friction stir welding

搅拌摩擦焊(FSW)过程中的对接面附近工件材料流动变形行为与许多缺陷的形成密切相关。通过开展搅拌摩擦焊试验,研究对接面附近材料在FSW过程中的流动与变形行为。针对AA2024-T3铝合金进行研究,通过采用预制氧化膜为标示材料的方法进行标示,并采用不同的焊接参数进行FSW试验。结果表明,预制氧化膜在焊接过程中完全破碎,在焊缝中以氧化铝颗粒的形式呈有规律的“S线”分布,并且随着搅拌头转速的上升,宏观上“S线”分布宽度降低,局部上氧化铝颗粒尺寸越大,分布越紧密。标示材料在接头中的沉积特征体现出,在较低的搅拌头转速下,对接面附近工件材料在FSW过程中经历了剧烈的应变,而随着搅拌头转速的提高,总应变量反而减小。

During friction stir welding(FSW),the flow and deformation of parent material near the butt surface is closely related to the formation of many defects.The flow and deformation behavior of initial butt surface material were studied by carrying out an experiment of FSW.AA2024-T3 aluminium alloy was utilized as parent material and processed under different welding condition.Oxide film was prefabricated on butt surfaces as marker material.All oxide films were broken into particles,deposited into the weld and formed a regular line named lazy S.The increasing rotation rate of the tool results in the decreasing of the width of the macro spread of lazy S,and meanwhile,in a specified area,the particles’size is coarser and the spread of them is narrower.The deposition pattern of the marker material reveals that low rotation rate of the tool introduces severe strain to the parent material near the butt surface during FSW process.However,as the rotation rate increasing,the total strain in the same area decreases.