The heterogeneity of dynamic recrystallization and texture evolution in stirring zone of Al-Mg-Sc alloy

Abstract

Friction stir processing (FSP) is a potential way to improve the mechanical properties of alloys. However, compared with the dynamic recrystallization (DRX) of pin, the effect of shoulder is not deliberately distinguished. In this study, the grinding stirring processing (GSP) was applied to Al-2.7 Mg-0.24 Sc alloy to isolate the effect of shoulder. The tool of GSP had the same features as FSP except that it had no pin. The shoulder in GSP formed the discontinuous DRX (DDRX) cores and the deformation bands throughout the processing zone. On the basis of this result, ten observed objects in stirring zone of FSP were selected to analyze the gradient of DRX and orientation. By the characteristics of the recrystallized grains, we found that the frequency with the aspect ratio of grains >1.8 was positively correlated with the frequency of DDRX. The distribution of aspect ratio revealed that although DDRX could not be ignored, continuous DRX (CDRX) was dominant, and the frequency of CDRX increased with the distance from the top increased. Finally, the analysis of texture showed that Goss texture was favorable to the CDRX. • Applying grinding stirring processing (GSP) to compare shoulder-effect and pin-effect systematically. • Clearly proved that the shoulder would participate in dynamic recrystallization (DRX), mainly discontinuous DRX. • Detailed analysis of grain boundary characteristics semi-quantified DDRX variation. • Evolution of texture revealed Goss texture was favorable to the continuous DRX.