抄録
This paper deals with the sufficient conditions under which an instantaneous source is able to be used instead of a moving source being a welding source. The error calculated from between the temperature of the instantaneous source and one of the moving source was investigated. The applicable conditions less than 1% and 5% error, respectively, were shown and was able to use for judging useful source from the informations such as welding speed, thermal diffusivity and the distance from between the aimed position of temperature and the weld center line. The approximate equations for maximum temperature rise of moving source, which are an accuracy of about 99%, were proposed.
