The impact of thermo-mechanical processing routes on product quality in integrated aluminium tube bending process. (July 2021) - Ma, J.
Graphical abstract: Highlights: Four processing routes integrating solution-heat-treatment, artificial aging, natural aging, and cold tube-bending are designed. The impact of different processing routes on dimensional accuracy and product properties in aluminium tube bending are investigated. Solutionizing immediately before bending significantly reduces springback and wall-thinning than the bending in T4-temper. In addition to increasing product strength, post artificial aging creates a uniform distribution of strength in the cross-section of bent tubes. Solutionizing before bending in combination with artificial aging after bending greatly expands the 'design space' for bent aluminium parts. Abstract: In response to the increased demand for high dimensional accuracy and mechanical properties of formed metal products, this research aims to provide new insights into the impact of thermo-mechanical processing routes on quality in integrated bending process for heat-treatable aluminium tubes. Based on carefully controlled experiments with four representative processing routes, including R1: solution-heat-treatment (SHT) → bending → artificial aging (AA), R2: SHT → bending → natural aging (NA), R3: SHT → NA → bending → AA, and R4: SHT → NA → bending, the impact of these routes on final geometrical dimensions and mechanical properties of bent parts is thoroughly evaluated. As compared with R2 and R4 routes employing naturally-aged tubes in the bending operation, R1 and R3 routes with bending of SHT tubes significantly reduce both springback by 50 % and wall-thinning by 26 %. Considering product strength, however, for the routes with AA, R3 can achieve 16 % improvement of the hardness as compared to R1; for the routes without AA resulting in products in T4-temper, R4 can make the average hardness 20 % higher than R2. Moreover, R1 and R3 routes can make a more uniform hardness distribution in the cross-section of bent tubes than the two others, meaning that AA reduces the hardening effect of pre-deformation. All these findings provide a knowledge basis for the selection of suitable processing routes as well as the design of new, customized processing routes for the efficient manufacture of value-added aluminium tubular products.