Hydrogen-assisted cracking is one of the most challenging aspects of the joining and environmental performance of welded structures. Hydrogen cracking, also known as delayed cracking, takes many forms depending on the source of hydrogen and includes fabrication hydrogen cracking, hydrogen-induced stress cracking, hydrogen-induced cracking, and stress corrosion cracking (SCC).
Hydrogen-assisted cracking occurs when atomic hydrogen enters steel and certain other alloys (such as aluminium and titanium alloys), where it can cause a loss of ductility or a reduction in load-carrying ability, or catastrophic brittle failures at stresses well below the yield strength or even the design strength for the alloys.
The financial impact of hydrogen-assisted cracking mechanisms is incalculable, and over the past 60 years TWI has been actively involved in helping the industry to cope with hydrogen, by, among other things: identifying dissimilar metal interfaces resistant to hydrogen from cathodic polarization; determining operating conditions for duplex and supermartensitic stainless steels subsea; and developing welding parameter limits to avoid fabrication hydrogen cracking.
TWI is a world leader in this field.
TWI has the facilities to study the properties of materials with hydrogen - from joining processes, cathodic polarization, gaseous hydrogen, high-pressure hydrogen facilities, corrosion, sour service and more.