The experiment at this stage mainly uses 316L stainless steel manufactured by Wire-arc additive manufacturing (WAAM). It is expected that the beneficial effects of grain refinement and residual stress accumulation can be achieved by adding LSP treatment in the WAAM process. The successful application of LSP between SLM layers by Nikola et al. from EPFL gave us such confidence.
First of all, we want to compare the effect of LSP on the directly formed curved surface and the cut flat surface. This is to study whether it is necessary to increase the interlayer milling process in the subsequent interlayer LSP experiment. Afterwards, a re-build experiment of interlayer LSP was carried out, and the effect of adding interlayer milling process on the overall microstructure was compared. In addition, Abaqus is used to simulate the LSP process when comparing effects of LSP to obtain the best deformation effect.
In this part of the experiment, the parameters of 316L manufactured by WAAM were first adjusted, and the best molding parameters were selected. LSP treatment was applied on the upper surface of the single walls.
This series of experiments shows that the use of LSP to achieve grain refinement is feasible, but it can only be combined with post-forming heat treatment to achieve the effect of static recrystallization. Performing LSP between WAAM layers is a great challenge. This is because the heat input of WAAM is too high, and the depth of the influence layer of the interlayer LSP cannot exceed the depth of the heat-affected zone, and recrystallization in the near-surface area may occur due to heavy recrystallization. Melting prevents recrystallization from occurring. Therefore, if you want to use LSP between WAAM layers, you need a stronger LSP effect and a smaller heat input.
This series of experiments aroused my interest in LSP on complex surfaces, which is why I will conduct LSP experiments on samples of complex surface additive manufacturing in the follow-up.
If you want to know how to perform LSP in ABAQUS, please refer to my VDLOAD subroutine