Numerical Simulation of Metallurgical Joining of AISI 304 Steel and Ti Grade 2

In the field of metallurgy, joining dissimilar metals poses a significant challenge due to differences in their physical and chemical properties. One such combination that has gained attention is the joining of AISI 304 steel and Ti Grade 2. These two metals have unique characteristics that make them ideal for various applications, but their differences in thermal conductivity, melting points, and chemical reactivity make achieving a strong and durable joint challenging. Numerical simulations are currently widely used to predict the behaviour of materials during the joining process, as well as to optimize welding parameters in order to achieve a sound weld. In this study, the temperature fields during laser welding of 2 mm thick plates of AISI 304 steel and Ti Grade 2 were analysed based on the numerical simulations of the welding process using ANSYS software. A simulation model for the production of butt joints was developed to assess the impact of laser welding parameters, including laser power, welding speed, and laser beam offset towards the AISI 304 side, on the temperature distribution and weld-pool characteristics. The moving laser heat source was modelled using the conical model with a Gaussian distribution of the laser beam power. The material properties of AISI 304 steel and Ti Grade 2 were calculated as a function of temperature using JMatPro software. The cooling of welding plates by convection and radiation to the argon shielding gas and surrounding air was taken into account using a boundary condition of the third kind. Using the Design of Experiment (DoE) approach, the influence of technological parameters such as welding speed and power on the size of the molten zone on the top and root of the weld was analysed. An optimization of welding parameters was performed, resulting in a surface that represents a basic estimate of the location of admissible solutions in the design space. The results from the numerical simulation and the DoE experiment were compared, and then appropriate technological parameters were proposed for experimental laser welding of the considered dissimilar metals.