Diffusible Hydrogen Testing in Australia

Abstract

Diffusible hydrogen content in weld metals is a determining factor in the development of hydrogen-assisted cold cracking. In view of the importance of accurate and reliable quantification of diffusible hydrogen content, a number of industry standards have been developed to provide guidance on standardisation of methods for measurement of diffusible hydrogen content. A variety of test methods are currently used by industry and research organisations for the measurement and qualification of consumables and these test methods are generally accepted to be valid and comparable. However, the maintenance and calibration of the various hydrogen test methods is a matter of self regulation and, for this reason, the reliability and reproducibility of results across various test methods and laboratories is currently a matter of interest for Australian industry. Further, a more advanced and rapid measurement system is being utilised and a broad-based, independent and closely controlled trial is required to compare against traditional test methods and validate its application. In order to address these interests, the current work was commissioned by the Welding Technology Institute of Australia (WTIA) Technical Panel 2 — Working Group on Welding Metallurgy, primarily to assess the comparative performance of the various test methods (mercury displacement, gas chromatography, hot extraction) across a number of Australian laboratories with a uniform sample set produced under controlled welding conditions. A secondary aim was to determine the validity of the rapid test method known as Hot Extraction at 400°C.