Study of Marangoni phenomena in laser-melted pools

In laser welding, as a concentrated flux of energy strikes a metal it melts the local area to form a pool. The physics of heat transfer, fluid flow and phase-change that characterize the growth-rate of this pool are very important in understanding the welding process. In particular it has been observed, in typical welding applications, that under the same nominal conditions the depth of the pool can vary substantially. This leads to variations in the quality of the weld seam and makes advanced automation difficult. The concentrated temperature gradient also affects the microstructure of the weld, and leads to a high thermal stresses concentration which may cause cracking. This paper uses the simple axisymmetric pool example, to demonstrate numerically the role of surface tension in the dynamics of the melt pool and also at the same time looks at post solidification stress history using a Control Volume approach.