Improving the forming performance of incrementally formed sheet parts with customized heat treatment strategies

Although incremental sheet forming (ISF) is an efficient way to manufacture customized parts, the forming performance and geometric accuracy of formed parts need to be improved to meet industrial application. One feasible solution for these problems is to adopt proper heat treatment strategies for the sheet material both before and during the forming process. In this paper, the effects of heat treatment before forming and heat-assisted forming on the formability and performance of formed parts were experimentally investigated. First, TA1 sheets were heat-treated at different temperatures before forming, and then the sheets were incrementally formed into the target shape with variable angles at different temperatures. After heat treatment, the strength of sheets was decreased due to the occurrence of recrystallization and the growth of grains. Meanwhile, the surface quality of formed parts was also improved with pre-heat treatment before forming. During the heat-assisted forming process, the sheet was softened and the deformation resistance was reduced with the increase of temperature. Therefore, the axial forming force was decreased obviously and the formability of the sheet was increased obviously. Furthermore, by adopting both heat treatment and heat-assisted forming, it was found that the forming force could be further reduced and the formability of the sheet and surface quality could be further improved. As for geometric accuracy, heat treatment has a good effect on improving it, while heat-assisted forming has adverse effect. These findings provide an effective heat treatment strategy for improving the geometric accuracy and surface quality of the incrementally formed parts with lower forming force.