1990 Volume 8 Issue 4 Pages 439-444
Transient responses of temperature and penetration to a step change in welding conditions were investigated using FEM calculation of three-dimensional heat conduction and TIC welding of mild steels. Correlations between welding parameters and transient response of temperature and penetration were clarified through the comparison of experimental results with calculated ones. In addition, the temperature distribution and heat flow in the workpiece were also analyzed, from which the main factors of welding parameters dominating the transient response were discussed.
Temperature and penetration showed different behaviors to a step change in welding parameters, and their transient responses were characterized by their variation rates from the former quasi-state to later one. With a step change in welding velocity, the characteristics of transient response of temperature showed identical behaviors regardless of the variation of step change and heat input. The same response was also observed in the transient change of penetration. The main factor dominating the transient response to the step change in welding velocity was the heat flow direction. The transient response to a step change in welding current or heat input showed the different characteristics depending upon the variation of heat input, which was caused from the heat flow rate in the workpiece.