Abstract
Surface temperature of specimen at the central axis of the welding electrode was measured by a Pb. S optical pyrometer in resistance spot welding of mild steel. The measured value was related to process of nugget growth. The relationship between them was investigated under various welding conditions and with or without shunt current for various thickness specimens.
The results of this study are as follows;
(1) Temperature measuring technique with optical fiber and infrared detector is an effectual method for investigation of transient thermal phenomena in resistance welding, because it is less sensitive to electric noise.
(2) The maximum surface temperature of specimen at the central axis of the electrode, the rate of temperature rise and the time when the rise in temperature is saturated are closely related to process of nugget growth qualitatively.
(3) Surface temperature of specimen in welding is fluctuated at twice the frequency of the weld current. The delay angle of the phase of temperature fluctuation by the weld current increases with weld time in resistance spot welding of 1.2 mm thickness sheet.
