The Benefit of the Process Combination of Wire Arc Additive Manufacturing (WAAM) and Forming—A Numerical and Experimental Study

Abstract

Wire arc additive manufacturing (WAAM) involves the deposition of weld beads layer by layer using an electric arc energy source. However, during this procedure, the properties of each layer may differ because of unequal thermal distribution, resulting in a difference in microstructure and, therefore, mechanical properties in between the layers. This negative effect can be compensated for by combining WAAM with a subsequent forming process to introduce dynamic recrystallization, which allows a more homogeneous microstructure distribution within the material. This paper investigates numerically and experimentally the hybrid process of combined WAAM and forming of fine-grained mild steel (FGMS) SG3/G4Si (1.5130) to achieve a high degree of recrystallization in all layers of the WAAM-deposited material. Three different possible combinations of WAAM and forming are considered regarding the sequence and setup of the processes to show their influences on the recrystallization behavior. It was found that combining welding and forming allows recrystallization of up to two layers; however, the top layer is not recrystallized. Preliminary simulation results show that this can be resolved by adding a top roller to induce plastic strain after welding, leading to recrystallization in the top layer. The found results promise a certain controllability of the recrystallization behavior.

Keywords

• WAAM
• forming
• process combination
• simulation
• recrystallization
• hardness