High speed X-ray observation of digital controlled submerged arc welding phenomena

Abstract

In this study, welding phenomena during submerged arc welding (SAW) were revealed with X-ray observation. In the experiment, the test coupon was placed between the X-ray source and high-speed camera. The area surrounding the arc was observed from an angle perpendicular to the welding direction vnat a frame rate is 3000\u2009f\u2009s–1. From the observation results, the droplet transfer, weld pool and molten flux (slag), which were previously unknown, were investigated. The droplet transfer mode is the spray transfer. With a high polarity ratio comparable to electrode negative (EN ratio), the transfer frequency decreases, but the droplet diameter increases, then changes to the globular transfer. The slag solidifies covering surface of the weld pool.