Numerical Analysis of the Effect of Sulfur Content upon Fluid Flow and Weld Pool Geometry for Type 304 Stainless Steel(Physics, Processes, Instruments & Measurements)

概要

論文の詳細を見る
In this paper, the effects of sulfur content on the thermocapillary convection in weld pools and the pool shapes of type 304 stainless steel for gas tungsten arc (GTA) welding process have been simulated numerically using a one-region continuum model. A newly developed model for calculating the influence of sulfur on surface tension temperature coefficients has been used. The condition for the computations are ; sulfur contents from 0.003 to 0.03 weight percent, 100A welding current, and a normal gravity environment. The predicted results indicated that if the sulfur content is below about 0.015% the flow is characterized by two opposite rotating vortexes and a singular velocity at the collision point between outward and inward flows on the weld pool surface, where the sign of the surface tension temperature coefficient changes from a positive to negative value. One vortex, driven by the positive surface-tension temperature coefficient, has a high strength, and the other, driven by the negative surface tension temperature coefficient, has a relatively weak strength. The inward flow develops with an increase of sulfur content, and eventually envelops the entire molted pool, and results in a deep penetration. The outward flow gradually becomes weaker and finally disappears. Meanwhile, the singularity of surface velocity is decreased simultaneously.
大阪大学の論文