Effects of Surface Active Elements on Pool Convection and Properties of the Welds

摘要

It is well known that surface tension force dominates the fluid flow in the weld pool (Marangoni effect), influencing weld penetration and properties of the weld. In fact, it has been recently reported by EWI that when a thin surface active element rich layer is coated to the surface of the metal, more than several times of penetration depth was increased for a Gas Tungsten Arc Welding (GTAW) process. The objective of the present study is to systematically study the effects of surface active elements for both GTAW and GMAW (Gas Metal Arc Welding), not only on fluid flow patterns and weld penetration, but also on the distribution of surface active elements in the weld pool and possible formation of defects. Among the many accomplishments achieved by the project, the most significant one is that mathematical models were developed for the first time having the capabilities to simulate the droplet impinging process and the effects of surface active elements for both spot and 3-D moving GMAW.