A Study on Back Bead Formation in Inclined-up Position of Plasma Arc Orbital Welding

Kim, Hyo-Won; Cho, Sang-Myung

Journal of KWJS 2009;27(1):71-78.
Published online March 12, 2009.

플라즈마 아크 오비탈 용접의 경사상진자세에서 이면비드 형성에 관한 연구

A Study on Back Bead Formation in Inclined-up Position of Plasma Arc Orbital Welding

Abstract

In the circumferential welding of pipe, welding phenomenon changes with the position of pipe. Especially in the overhead position, back bead of vertical-up position would be sunk. To investigate the size of back bead and keyhole with the change of the flow rate of pilot and shield gas at each position, bead-on plate welds were conducted on 6mm thickness SS400 with inclined-up position. When the rest of welding conditions remained constant, the width of back bead was increased as the flow rate of pilot gas was increased. And back bead tended to convex as the flow rate of shield gas was increased.

Key Words: Plasma arc welding, Orbital welding, Keyhole welding, Inclined-up position, Overhead position, Convexity ratio, Back bead, Pilot gas flow rate, Shield gas flow rate