Initiation and Propagation Characteristics of Lamellar Tearing and Root Cracking in Corner Joint

Lamellar tearing of opening type and root cracking occasionally occur in multipass welded corner joints.In this paper, initiation and propagation characteristics of these cracks are examined by measurement of acoustic emission (AE) or weld cracking test, and effects of diffusible hydrogen and preheat-interpass temperature on them are investigated. The result of AE measurement reveais well initiation and propagation characteristics of these cracks. Effects of diffusible hydrogen and preheat-interpass temperature are hardly observed on lamellar tearing of opening type which occurs at the position away from the heat-affected zone. The lamellar tearing is initiated and propagated principally by the developement of welding stress and strain. Root cracking in multipass welded corner joints is initiated mainly by these stress and strain.It is propagated under them, being subjected to the influence of diffusible hydrogen and preheat-interpass temperature.