焊前打磨对6005A-T6铝合金型材搅拌摩擦焊接头性能的影响OA

To address the question of whether pre-weld mechanical polishing is necessary to remove the surface oxide film on 6005A-T6 aluminum alloy profiles for rail vehicles,the effects of unpolished and polished pre-weld treatments on the mi-crostructure,microhardness,tensile properties and fatigue properties of friction stir welded(FSW)joints were comparatively investigated under high-speed welding conditions with a rotational speed of 2 000 rpm and a travel speed of 2 000 mm/min.The results indicate that the high-speed FSW process can effectively break up the oxide film in the weld.The microstructure,microhardness distribution and tensile strength of the joints under both conditions show no significant differences,with the microhardness exhibiting a"W"-shaped profile and the minimum value located in the heat-affected zone(approximately 68 HV).The fatigue strength at 10⁷ cycles is approximately 105 MPa for the unpolished joints and 110 MPa for the polished joints,showing minimal difference.After NaOH etching,the"S-line"in the nugget zone of the unpolished specimens is more distinct than that of the polished specimens;however,neither tensile nor fatigue fracture propagates along the"S-line"under both conditions,indicating that pre-weld polishing is not a necessary procedure under high-speed FSW conditions.