The grain refinement of Al-6061 via ECAE processing: Deformation behavior, microstructure and property

In the past decade, a lot of efforts have been provided to explore the production of bulk ultrafined/nanostructured materials directly from microstructured ones via severe plastic deformation (SPD), especially through equal channel angular extrusion/processing (ECAE/ECAP). In this research, a comprehensive study of ECAE processing of bulk Al-6061 material was conducted. The best process route for nanostructured/ultrafined processing of bulk material was identified via comparing and simulation of different processing routes. 16 passes of ECAE processing by both of the physical experiment and finite element (FE) simulation were carried out, which have not been reported in available literatures and filled up the research blank after 8 passes of ECAE processing of Al-6061. To investigate the effect of original material status on the performance of ECAE processing, two different heat treatment specimens were prepared for investigation of the deformation behavior, microstructure evolution and property enhancement in ECAE processing. Through experiment, it is found that there is no nanostructure obtained in even up to 16 passes of ECAE processing for Al-6061. The best grain refinement is only at ultrafined level and the finest grain size is 0.71 μm. There is basically no grain refinement after 8 passes of ECAE processing. In addition, the relationship between the mechanical properties and the pass number of ECAE processing is orchestrated and compared with peer researches. The research presents a panorama of the ultrafined ECAE processing of Al-6061.