Metallographic organization and tensile properties of FSSP-modified H62 copper alloy surface

In this study, the surface of friction stir surface processing (FSSP)-modified copper alloy was altered by different passes of modification and lower pressure after selecting FSSP process parameters. The results showed that the grain size of the modified copper alloy surface was refined under various processes. In the modified section, the grains changed from fine equiaxed grains to rolling strips from the surface layer to the bottom of copper alloy sheet. FSSP could change the surface metallographic organization but could not change the internal structure of the sheet. The hardness values of samples obtained under various processes were higher than those of base metal, but the hardness of modified boundary region was slightly lower than that of base metal. The tensile strength of samples obtained under various processes was higher than that of base metal. Among them, FSSP was the best after one pass of modification, followed by two passes, and the worst was three passes. Most of the stretches appeared on the advancing side, and only a few appeared on the retreating side. The tensile parts had a honeycomb-type morphology, with a ductile fracture mode.