This study investigates the feasibility of using infrared sensing devices to measure the surface temperature variation near the molten pool and to correlate this temperature variation with the changes in welding parameters. Since the properties of the welds depend upon their microstructures and compositions, the cooling rate of the weld pool exerts a strong influence on their properties. If a valuable relationship could be found, the output signal from the infrared detector might be used as a feedback signal to control the laser welding process. In the present study, a simple method of monitoring the variation of cooling rate is proposed. Using two infrared temperature sensing devices together with a personal computer, we can calculate the cooling rate variation of a specified point of welds. From the results, it is concluded that mutual relations exist between measured cooling rate and microstructures as well as the properties of welds.
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE