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tration in the weld joint. In some cases, such hydrogen localisation is even intensi ed after weld heat treat-A brief overview is given of the role of hydrogen ment has been carried out.trapping in hydrogen management of steel At this point, it is worthwhile to discuss the hydrowelding. The concept of hydrogen trapping is introduced in conjunction with efforts in reducing gen pro le across a high strength steel weld hydrogen cracking in steel welding. Appropriate joint, reported by Musiyachenko and Kasatkin, 2 selection of hydrogen traps offers the potential to as shown in Fig. 1. A weldment, having an initial control the content and distribution of hydrogen in nominal hydrogen content of 2•5 mL/100 g metal steel weldments. The effectiveness of hydrogen (1 mL H 2 /100 g metal=0•89 wt-ppm hydrogen in traps through selective alloying in reducing the steel ), was post-weld heat treated at 700°C, for stress concentration of diffusible hydrogen during relief and hardness reduction. As expected, the nomwelding thermal cycles is evaluated, particularly in inal hydrogen content of the weldment decreased to its use as a substitute for costly weld heat 0•5 mL H 2 /100 g metal. In the meantime, hydrogen treatment practices. The relationship of weld metal accumulated at the fusion line of the weldment with microstructure and hydrogen contents to the effective use of hydrogen trapping elements is a concentration not lower than the value before the discussed. The fundamental aspects which control treatment. The localisation of hydrogen was thought hydrogen content as well as hydrogen distribution to occur due to stress assisted diVusion as well as in steel are discussed, such as the statistical dislocation assisted transport of hydrogen. It was not thermodynamics and the transport of hydrogen in clear why an unusually high post-weld heat treatment steel containing traps. As tools for investigating temperature was applied in that study. Such a temperpotential hydrogen traps, several experimental ature is more commonly used for the stress relief methods are discussed in relation to their necessary for prevention of temper embrittlement, applicability to characterise the physical nature of which is caused by embrittling species other than hydrogen traps. These methods include the hydrogen. However, a weld joint would have a higher hydrogen permeation technique and hydrogen thermal desorption analysis. Recent efforts to restraint stress if normal post-weld heat temperatures prevent hydrogen cracking in steel weldments were applied to the weld joint, which would consethrough numerical computations require quently produce a larger amplitude of hydrogen consideration of hydrogen trapping in the weld accumulation. microstructure, and hence knowledge of applicable Considering the above perspectives, attempts to data of hydrogen trapping parameters is necessary improve welding consumables have evolved towards for welding engineers to improve hydrogen the reduction of weld heat treatments. Welding promanagement in steel welding. IMR/380 ...

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