Numerical analysis of influence of quenching rate on coagulation process in welding fume formation

Abstract

This study aims to clarify fume formation mechanism theoretically through visualization of fume shape. In this paper, influence of quenching rate on fume formation process was investigated through numerical analysis with the fume formation model. The fume formation model consisting of heterogeneous condensation model, homogeneous nucleation model and coagulation model has been developed. The fume formation process under the condition assuming fume formation from iron vapor in MIG welding was visualized through visualization with numerical simulation. As a result, it was found that around 1000K, diameters of secondary particles approach an order of hundred nanometer at maximum. Those typically become chain shape consisting of primary particles. The diameters of primary particles become larger for lower quenching rate because of occurrence of coagulation among particles in liquid phase.