In situ measurement of ultrasonic behavior during lap spot welding with laser ultrasonic method

Understanding the joining process in real time during welding can help improve quality, reliability, and manufacturing efficiency. For this purpose, a laser ultrasonic method that detect situ quality without contact would be useful. However, behaviors of propagation as well melting with increasing temperature remain unclear. Therefore, study aimed to experimentally investigate in-process behavior when using method. Lapped tungsten inert gas (TIG) arc spot was used for measurements, wherein ignition TIG from specimen's top surface irradiation measurement bottom occur simultaneously. In welding, width at interface lapped plates is an important parameter. We investigated type ultrasonics measure examined whether could captured. The results show velocity decreases increases. echo between disappears, appears. disappearance appearance each facilitate understanding welding.