In recent years, significant progress has been made toward understanding the development of the weld pool shape and size from the numerical calculations of heat transfer and fluid flow in the weld pool. Although such calculations have provided detailed information about the welding processes, no efforts have been made to understand the development of fusion zone microstructures from the fundamentals of transport phenomena. The aim of this work is to address this. Heat transfer and fluid flow during manual metal arc welding of low-alloy steels containing different concentrations of vanadium and manganese were investigated by solving the equations of conservation of mass, momentum and energy in three-dimensional transient form. The model incorporates fluid flow in the weld pool resulting from surface tension, electromagnetic and buoyancy forces. The cooling rates are calculated at various locations in the weldment. The weld metal compositions are used to calculate the time-temperature-transformation (TTT) diagrams on the basis of an available phase transformation model. The calculated cooling rates and the TTT diagrams are then coupled to determine the continuous cooling transformation (CCT) behavior and volume percentages of acicular, allotriomorphic and Widmanstatten ferrites in various low-alloy steel weldments. The computed microstructures are found to be in good agreement with the experimentally observed microstructures. The agreement indicates significant promise for predicting weld metal microstructure from the fundamentals of transport phenomena.
|Original language||English (US)|
|State||Published - Apr 1997|
All Science Journal Classification (ASJC) codes
- Metals and Alloys