Rapid Determination of Diffusible Hydrogen in Steel Welds Using a Modified Gas Chromatography Facility

A new procedure that makes use of a modified hot extraction module for the rapid extraction of diffusible hydrogen and a conventional gas chromatograph for its measurement has been developed for the determination of diffusible hydrogen contents in welds. Using this procedure, diffusible hydrogen measurements were carried out for weld specimens prepared by depositing weld metal using electrodes having diffusible hydrogen contents in the range of 4 to 29ml per 100 g. The results obtained show one-to-one correspondence with the results obtained when using the ISO 3690 mercury method. Further, following the recommendation of ISO 3690, the results obtained using both methods were statistically analyzed via Student's t test. The analysis showed, with a confidence level better than 95 %, that the results obtained via the new procedure were as accurate and reproducible as those of the standard method. The hot extraction chamber and the gas chromatograph can be integrated easily into a dedicated diffusible hydrogen measurement system. This new procedure has the potential to replace the time-consuming mercury method and the commercially available hot extraction method currently employed for measuring diffusible hydrogen contents in welding consumables.