Geometry effect assesment on mechanical performance of forge welded pipe

Abstract

Shielded Active Gas Forge Welding is a robust and efficient solid state welding method applicable to offshore and oilfield applications. The mechanical or fracture performance of the welded connection may be influenced by the forge weld shape. In this paper the main focus is on the geometry effect of weld shape and defects on forge weld mechanical performance and fracture behavior. The potential impact of variables on the undercut description is parametrically analyzed by finite element calculation. As for the undercut located in the transition region between weld and base material, our studies show that the outer undercut of more than 0.3 mm has a significant impact on mechanical behaviour of welded pipe. When the undercut is located in the fusion plane, its impact on mechanical performance of welded pipe is negligible. Weld caps are beneficial since they contribute to weakening the driving forces for crack propagation. Even if the effect of undercut is considered, the beneficial contribution of weld cap still exists.