Abstract
The purpose of this investigation is to make clear the fundamental phenomena in cooling and solidification process and to establish the methods of estimating hot crack sensitivity and preventing hot crack on welds of Al alloy. In this experiment, temperature measurement was perforemed with CA thermocouple in cooline and solidification process on TIG arc spot welds of commercial Al alloy 2024 and 5083.
Maximum temperature in molten pool (Tmax) and several cooling rates at some positions of molten pool (Cmax, Cfp, Cm) were analyzed.
Distribution of Tmax in molten pool was helmet-shaped distribution, and the Tmax had a maximum value at the center of molten pool and it was in the range of 980°C-1050°C. And the difference of Tmax at any position of molten pool amonge three materials was under 100°C. It is not thought to be so large.
In any cooling rate, the difference fo cooling rate in Al alloys was smale but there was some difference between Al alloy and pure Al apparently, and the coiling rate Al was larger than one of Al alloy. It is thought to be due to the difference of heat conductivity.
Cooling rate in the case of small heat input was larger than in the case of large heat input, in any materials.
