In the present work, a three-dimensional numerical model for MAG (Metal Active Gas) welding of thin plate is developed. In MAG welding, metal is deposited into the molten pool from the electrode wire, and the metal plays an important role in determining weld bead profiles. In the model, the thermal energy enters the plates through two mechanisms, i.e., direct heating from arc plasma and indirect heating by melting wire. The transient temperature distribution on base metal is numerically analyzed in order to estimate the molten pool size by using a finite difference model based on heat flow equation, and the theoretical configuration of molten pool is calculated, taking account of the balance of gravity, surface tension and arc pressure.By using these models, the transient MAG welding process is numerically analyzed. The numerical results are in good agreement with the experimental results for bead-on-plate-MAG welds on mild steel plate. Accordingly, it is concluded that the model, proposed in the present work, is useful for prediction of MAG weld bead formations.
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