Investigation of electrode and hydrogen induced crack in welded joint of dissimilar steel

The welded joint of dissimilar heat-resisting steels 20Cr12MoV (F12) and 12Cr2MoWVTiB (102) generally works around 600℃. Newly-developed R507 MoNb electrodes, being tested for elevated-temperature prop erty, oxidat ion resistance and creep rupture strength, have fulfilled the technical standards concerned and passed the examination of on-the-spot operation.In this paper, three kinds of ferritic electrodes are used for testing. They are the R817 high-strength electrode (Cr11 MoVNi), the R347 low-strength clectrode(Cr2MoVWB) and the newly-developed R507MoNb medium-strength electrode. The study of the influence of those three different electrodes on carbon migration, the hydrogen induced crack (HIC) and hydrogen diffusion shows that the medium-strength electrodes can well control the carbon migration, and that the tendency to have HIC in the joint formed by R817 is smaller than that by R347 instead. Considering the effect of weld metal transformation on the restraint stress and hydrogen concentration of a joint, the hydrogen distribution in the heat-affected zone is calculated by using finite element method with stress and strain changing, and so the effect of the transformation behaviour on HIC is revealed.