Determining the boundary conditions of weld metal hydrogen cracking

Shaun Smart
Industrial Fellow 2019
ERA Foundation Fellow 2019

Shaun Smart
TWI Ltd and the University of Leicester

Shaun is working to better understand the conditions that cause hydrogen cracking, a process that occurs in metal fabrication and reduces the load-bearing capacity of metals.

Weld metal hydrogen cracking occurs when decomposed hydrogen created during welding produces hydrogen ions. These ions are absorbed into the molten weld pool and remain there during solidification. They then interact with microstructural features, such as dislocations, grain boundaries and vacancies, resulting in high localised stresses and ultimately the cracking of the weld metal if certain conditions are present.

While work has been done to understand certain types of hydrogen cracking, for example Heat Affected Zone (HAZ) hydrogen cracking, there is little published data defining when weld metal hydrogen cracking becomes the dominant mechanism.

Shaun will expand on knowledge of weld metal hydrogen cracking as a failure mechanism separate to HAZ hydrogen cracking and move towards defining control measures specific to its avoidance.

“I can continue working while undertaking this research, so the Industrial Fellowship is a great fit for our company and for this research in particular,” says Shaun.

Shaun is a Senior Project Leader in the Arc Welding Engineering department at TWI, Cambridge. He has been with the company for 10 years, before which he worked as a soldier and tradesman in the Royal Electrical and Mechanical Engineers of the British Army. He completed a BEng (Hons) while working at TWI.