Yuzhen ZHAO
,
Yongping LEI
,
Yaowu SHI
,
null
,
null
材料科学技术（英文）
A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80×10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 125×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 20~150×10-6.
关键词:
Surface-active elements
,
null
,
null
,
null
Yongping LEI
,
Xianghua GU
,
Yaowu SHI
材料科学技术（英文）
A mathematical model to describe the heat transfer and fluid flow in the mutually coupled weld pool and are by an interactive free surface of the pool for a stationary gas tungsten are welding (GTAW) is developed. The two sets of governing equations and auxiliary formulas, controlling the weld pool and plasma are systems respectively, were solved by a finite difference method. A boundary-fitted coordinate system was adopted because the free surface has a curved and unknown shape during welding. The results of this work provide a fundamental basis for predicting the behavior of an integrated weld pool and are system from first principles.
关键词:
