Study on Prevention of Weld Cracking in Thick Weldment (Report 1)

Hydrogen Distribution in Thick Weldment and its Change with Post-heating

Abstract

This paper deals with the diffusible hydrogen in multilayer weldment with plate thickness 100 mm to 200 mm.
The hydrogen distribution in thick weldment are examined by the experiment. The following facts were clarified.
(1) Diffusible hydrogen content in weld metal is raised with an increase of the number of welding layer. The maximum position of diffusible hydrogen content in thickness direction exists at just under the last layer and its distribution can be shown as Fig. 5 and Fig. 7. The hydrogen contents of maximum position was raised with an increase of the number of welding layer.
(2) Maximum hydrogen contents, above mentioned, is reduced about 30 per cent with locally postheating for 0.5 hr at 300°C, and diffusible hydrogen is almost removed with furnace annealing for 2 hr at 625°C.
(3) Diffusible hydrogen remains for a long period in thick weldment, for example, it remains over 60 days in 100 mm thick weldment of A 387 Gr D steel (2 1/4Cr-1 MO Steel).