Investigation of diffusible hydrogen content in drawn arc stud weld metal

The fully mechanized drawn arc stud welding is a welding procedure for joining pin-shaped elements. In particular, it is an established joining technique for large studs in steel construction. The process is characterized by its high heat input due to high current and a weld pool protection realized by a ceramic ferrule holding the metal vapor as a shielding gas. Turbulences inside the ferrule during welding cause contaminations with atmospheric humidity. Furthermore, a high cooling rate results in a locally strongly hardened heat-affected zone and a considerable residual stress state in the parent material. Thus, there is a risk of enhanced hydrogen cracking susceptibility, especially for stud welding on high strength steels or under adverse welding conditions. An analysis procedure for determination of diffusible hydrogen content in drawn arc stud weld metal is presented in this article. This novel method is based on carrier gas hot extraction according to ISO 3690.