Akademik Veri Yönetim Sistemi
Journal of Materials Engineering and Performance, 2025 (SCI-Expanded)
WAAM (Wire Arc Additive Manufacturing) is an additive manufacturing method using arc energy as the energy source and welding wire as the raw material. Unlike additive manufacturing, it has excellent advantages, such as significantly reducing raw material utilization rates and increasing production speed in manufacturing large and complex parts. However, WAAM has problems with surface roughness, metallurgical bonding, and residual stress. Due to the nature of additive manufacturing in WAAM, repetitive heating and cooling directly affect the microstructure and phase formation. Understanding the microstructure and phase changes due to repetitive heating and cooling in WAAM with the help of computational methods is very important in the pre-production prediction of the material's microstructure. This study used ER70S-6 (AWS A5.18) steel welding wire in the high-strength low-alloy steel group. CMT-equipped MIG welding type, which can provide a high level of heat input control, was used as a welding method. Three walls with the same number of layers at three different heat inputs were produced by the MIG-CMT method in WAAM. Transverse and longitudinal sections were taken from the produced walls, and microstructure examinations were carried out. Microstructure examinations were carried out along the part in the deposition direction in both sections, and grain orientations were observed. Mechanical characterization was performed using microhardness measurements from the walls. Cooling rates were calculated for the production, followed by a thermal camera. Time, Temperature, and Transformation (TTT) diagrams were created using the Thermo-Calc computational materials engineering program based on the CALPHAD methodology under material-specific conditions. The cooling curves of the production are shown in the TTT diagram. It was observed that the phases obtained by the experiments, the phases obtained by the computational method, the phase ratios calculated in the optical microscope, and the phase ratios calculated in Thermo-Calc were the same. The microhardness values measured along the cross section decreased in the sections where the grain size increased and increased where the grain size decreased. It was observed that the microstructure formation and average grain size because of the manufacturing process with different heat inputs did not show a sharp change, and the average grain size measured by optical microscopy and the phase types identified were consistent with the data obtained by EBSD. As a result, the relationship between process, microstructure, and mechanical properties is explained. Thermo-Calc computational materials engineering program was found to be promising in additive manufacturing with its benefits such as reducing experiment repetition and providing flexibility to research.