异种钢接头的焊条及氢致裂纹

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

异种耐热钢20Cr12MoV(F12)和12Cr2MOWVTiB(钢102)焊接接头在600℃高温下工作,研制了新R507MoNb焊条,所焊的异种钢接头经高温性能、抗氧化性及持久强度等检测,全部符合标准要求。并通过了现场运行考核。本文还采用3种匹配的铁素体焊条:与20Cr12MoV钢相匹配的高强焊条R81T(Cr11MoVNi),与12Cr2MoWVTiB相匹配的低强焊条R34T(Cr2MoWVB)以及新研制的中间匹配焊条R507MoNb,研究了3种匹配焊条对异种钢接头氢致裂纹的影响,结果表明:用高强焊条R817所焊接头的氢裂倾向反而比用低强焊条R34T时小。本文分析了焊缝金属相变对接头拘束应力及氢分布的影响,揭示了焊缝相变行为对接头氢裂倾向的影响机制。

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.