Effects of Material Properties on Transient Response in GTA Welding

概要

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Effects of material properties on the transient response of temperature to a step change in welding speed were investigated using GTA welding and FEM calculations of three-dimensional heat conduction. The materials used in this study were stainless stell, mild steel, brass, aluminum alloy and copper, each 9 mm in thickness. In GTA welding of low heat-conductive materials, large differences in maximum temperature appear in the period between the former and latter quasi-stationary states. On the other hand, high heat-conductive materials indicate a large difference in temperature gradient, but only a little change in maximum temperature. In addition, the high heat-conductive materials require more distance or time to be in the latter quasi-stationary state. The transient response from the former to the latter quasi-stationary state is characterized by the rate of change of the maximum temperature and the temperature gradient between the two quasi-stationary states. The experimental results are confirmed by FEM calculations based on three-dimensional heat conduction. It is also clarified that although the maximum temperature mainly depends upon heat conductivity and thermal diffusivity, the transient response is dominated only by thermal diffusivity.Highly thermal diffusive materials show slower response to a step change in welding speed.
1993-10-01