Diffusible Hydrogen Content Depending on Welding and Cooling Parameters

Abstract

Safety of welded components made from high-strength materials is assured above all by the avoidance of hydrogen-assisted cold cracking which occurs during fabrication and may have effects during service. In this context, continuous advancement of the procedures and standards for hydrogen analysis is required. Exact determination of the weld metal diffusible hydrogen according to ISO DIS 3690 is therefore highly relevant as regards the welding and cooling parameters to be maintained. In the investigations presented in this paper, the influence of the welding process parameters and of the cooling parameters on the diffusible hydrogen content was examined and the procedures and parameters specified in ISO DIS 3690 for the weld specimen preparation were checked. The influence of cooling conditions, arc length and contact tube distance (CTD) on the weld metal hydrogen concentration was studied for a high-strength flux cored wire electrode and a high-strength solid wire electrode. Measurement of the diffusible hydrogen was carried out by means of carrier gas hot extraction using a sensitive and long-term stable thermal conductivity detector (TCD).