The role of prestraining on mechanical properties and microstructure of preaged AA 6016 Al-Mg-Si sheets

• Published in: Journal of alloys and compounds Vol. 960; p. 170681
• Main Authors: Cui, Min, Kayani, Saif Haider, Kim, Hyoung-Wook, Lee, Je-Hyun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2023
• Subjects: Al-Mg-Si alloy; Formability; Microstructure; Preaging; Prestraining; Prestraining; Al-Mg-Si alloy; Formability; Preaging; Microstructure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.170681

In this study, we investigated the role of prestraining (at 3% and 5%) on the mechanical properties and microstructure of preaged (PA) Al-Mg-Si sheets before and after paint baking (PB). By applying prestraining after preaging (PAPSx) (before PB), the work hardening rate and the uniform elongation were largely reduced as compared with the PA material, but when prestraining was applied before preaging (PSxPA), they were reduced at a lower rate. However, in the tensile test curves of PSxPA materials, the Portvein–Le Chatelier effect was observed, which was attributed to the segregation of clusters and solutes on dislocation lines. After PB, PAPSx materials obtained a higher yield strength (YS) with finer precipitates and a higher number density than PSxPA, and the only PA materials. By contrast, PSxPA materials created large-size precipitates with a lower number density, but the YS was higher than that of PA material. PSxPA could maximize the improvement of the bake-hardening response. A lower level of prestraining (≤3%) was preferred for PSxPA materials because it did not increase YS considerably before PB, which was beneficial for the stamping process. The relationship between clustering behavior, precipitation behavior, and mechanical properties is discussed in detail. •The PLC effect was observed in the PAPSx materials before PB.•PAPSx materials obtained the highest PB yield strength but low BHR.•PSxPA materials had higher PB yield strength than the PA material and could maximize the improvement of the BHR.