Simulation and experimental study of 3 pass butt joint welding process with heat source model and user subroutine to predict temperature distribution and hardness

This fundamental research delineates new developments in cooling rate subroutines and heat source models in GMAW multi-pass welding simulations, the outcomes are then compared with the experimental result. The software used to perform the welding simulation is MSC Marc, one of the nonlinear finite elements analysis software used to simulate the behavior of complex materials and interactions. This research uses S235 material structural steel as a specimen, which is widely used in construction and uses ER70S-6 for filler material. Before the actual welding process begins, an initial analysis is needed to design the geometry, in which the physical and mechanical material properties are required. The cooling time and material must also be determined using a subroutine, as these features are not available in the simulation software. After modeling and formulation are completed, the Goldak double ellipsoid heat source model (HSM), cylindrical HSM, and rectangular HSM are used for the simulation. A subroutine is also included in the simulation so that material hardness can be obtained as a simulation result. This research produces a simulation process that provides values very close to the actual welding process, as demonstrated by the comparison between the simulation methods and the experimental method. The subroutine developed in this research can be used as a reference for conducting actual welding processes in predicting weld material hardness as an impact of cooling time and microstructural changes due to multipass GMAW welding.