Local Thermomechanical Processing for Improving Formability of High Strength Aluminum Sheets
2022-01-0278
03/29/2022
- Event
- Content
- Limited room temperature formability hinders the wide-spread use of high strength aluminum alloys in structural body-in-white parts. Stamping or extrusion at warm temperatures or from softer tempers are the current solutions. In this work, our approach is to start with age- and work-hardened sheets from 7xxx, 6xxx, and 5xxx family of alloys and improve their formability using local thermomechanical processing only in the regions demanding highest ductility in the forming processes. The processes used were friction stir processing (FSP) and roller bending-unbending. In both the methods sheets were locally deformed and heated simultaneously without any change in the final sheet geometry or chemistry. Initial results indicated significant deformation in the processed zones with minimal sheet distortion. FSP also resulted in dynamically recrystallized, fine grained (d <5 µm) microstructures in the processed regions with textures significantly different from the base material. This resulted in formability improvements of > 30% in 7085-T76 and > 50% in 6111-T6 alloys as measured by minimum bend radius (r/t) ratios established with V-bending tests performed at 90 and 180° bend angles. The formability improvements were independent of the tested surface of the sheet and its finish. Based on the encouraging initial results, we envision applicability of these processes in both pre- and post-stamping stages through integration of the process tools as end-effectors to robotic arms.
- Citation
- Nasim, W., Das, H., Kulkarni, S., Rohatgi, A. et al., "Local Thermomechanical Processing for Improving Formability of High Strength Aluminum Sheets," SAE Technical Paper 2022-01-0278, 2022, .