Thermal Control to Optimize Deposition Rates in Wire Arc Additive Manufacturing (WAAM). Application to Stainless Steel Alloys Using Dual-Wire TIG Welding: Optimization of Microstructure and Stress Distribution
Abstract: Wire arc additive manufacturing (WAAM) enables the production of parts measuring several cubic meters in size and of moderate complexity by depositing metal layer by layer. This competitive process, tailored to industrial needs, is characterized by high productivity and high-value-added steps. However, the inevitable use of an intense, localized heat source generates complex physical phenomena that cause collapses, deformations, and residual stresses, all of which adversely affect the performance of the process and the parts produced. To minimize these defects, an initial innovative strategy developed in this work involves positioning the filler wires within the electric arc to optimally distribute the input energy across the base metal.
This method improves the instantaneous deposition rate from 1 to 5.2 kg/h. Another approach being studied involves controlling solid-state phase transformations to reduce volumetric distortions within the workpiece, which lead to deformation and residual stresses. To achieve this, new alloys are developed in situ by simultaneously mixing two stainless steels, thereby generating promising microstructures and thermomechanical behaviors. Depending on the conditions, these alloys can reduce deformations by up to 45% and the magnitude of residual stresses by as much as 61%, and ultimately refine the microstructure by 99% (reaching approximately 10 μm), thereby improving the performance of parts manufactured using the WAAM-TIG process.
Keywords: Dual-wire arc additive manufacturing, deposition rate, stainless steels, solid-state phase transformations, microstructures, deformations, residual stresses
Thermal Management for Optimized Deposition Rate in Wire Arc Additive Manufacturing (WAAM). Application to Stainless Steel Blends Using Dual-Wire TIG: Optimization of Microstructure and Residual Stress Distribution
Abstract: Wire Arc Additive Manufacturing (WAAM) enables the production of moderately complex parts measuring several cubic meters by depositing metal layer by layer. This cost-effective and industry-adapted process stands out for its high productivity and high-value-added steps. However, the inevitable use of an intense and localized heat source generates complex physical phenomena that lead to collapses, deformations, and residual stresses, all of which are detrimental to the performance of both the process and the parts produced. To address these issues, the first innovative strategy developed in this work involves positioning the filler wires within the electric arc to optimally distribute the input energy throughout the base metal.
This approach significantly improves the instantaneous deposition rate, increasing it from 1 to 5.2 kg/h. Another method currently under investigation focuses on controlling solid-state phase transformations to minimize volumetric distortions in the part, which are responsible for deformations and residual stresses. To achieve this, new alloys are developed in situ by simultaneously blending two stainless steels, resulting in promising microstructures and thermomechanical properties. Depending on the conditions, these alloys can reduce deformations by up to 45% and the magnitude of residual stresses by 61%, while also refining the microstructure by 99% (reaching a scale of around ten μm), ultimately enhancing the performance of parts manufactured using the GTAW-WAAM process.
Keywords: Double-Wire Arc Additive Manufacturing, deposition rate, stainless steels, solid-state phase transformations, microstructures, strains, residual stresses
