搅拌头转速对球墨铸铁/低碳钢搅拌摩擦搭接接头强度的影响

Effect of Rotating Speed of Stirring Pin on Strength of Friction Stir Lap Welded Joint of Nodular Cast Iron/Low Carbon Steel

对铁素体基球墨铸铁和08F低碳钢实施了拌摩擦搭接焊,利用拉伸机、扫描电镜和光学显微镜,研究了搅拌头转速对接头拉剪剥离强度和显微组织的影响。固定搅拌头进给速度为60 mm/min,搅拌头转速增大到800 r/min后,接头拉剪剥离强度增大很快,搅拌头转速1000 r/min对应的接头断裂于低碳钢母材处,其拉剪剥离强度最大达到3907 N/cm。若搅拌头转速过低,搅拌区形成带状石墨聚集区,成为接头断裂路径,降低了接头强度;提高搅拌头转速可有效促进两材料搭接面接合,有利于石墨颗粒分布均匀,从而提高接头强度。

The friction stir lap welding was implemented to join nodular cast iron and low carbon steel.Effects of rotating speed of FSW tool on tensile-shear load and microstructure were investigated by means of tensile tester,scanning electron microscope and optical microscope.The result revealed that tensile-shear loads increase rapidly when rotating speeds of FSW tool exceed 800r/min with a fixed feed rate of 60mm/min.Tensile-shear loads of samples welded at 1000r/min reach a peak(3907N/cm),which are broken at the base metal of low carbon steel.Ribbon-shaped graphite gathering areas form in the joint under low rotating speed of FSW tool condition,which become the fracture path and reduce the strength of the entire joint.Increasing the rotating speed of FSW tool can effectively promote the fusion of the adjacent areas on both sides of the stir zone,which is favorable for the uniform distribution of graphite particles and improves the entire joint strength.