The reasons for the black line defects on the surface of 6082 aluminum alloy extruded profiles were analyzed through macroscopic examination,microstructure observation and micro-area composition a-nalysis.The results showed that the defects existed in the form of non-metallic inclusions of oxides and car-bides mainly composed of Al.There were coarse Mg and Si phases around the defects,or accompanied by excessive precipitation of Si.Through strict control of the quality of raw materials,extrusion and casting processes,eliminating C and O elements,as well as refining Mg and Si phases by modification treatment and component overcooling,black line defects could be effectively eliminated.
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