Review of Real-Time Temperature Measurement for Process Monitoring of Laser Conduction Welding

Laser welding has been applied to various industries, in particular, automotive, aerospace and microelectronics. Primary aim of joining two metals by keeping their properties unaltered, that can be only possible by controlling temperature, heating and cooling rates. However measurement of weld pool temperature during laser spot welding is a difficult task because of the short pulse duration, often lasting only a few milliseconds, highly transient nature of the process, and the presence of a metal vapour plume near the weld pool. This paper deals with the application and developments of acoustic, optical, thermal, spectral and ultrasonic techniques for weld pool temperature monitoring. The advantages and limitations of these techniques are also discussed.