Intercrystalline corrosion of surface-welds of nickel alloys on carbon steel

ISSN： 0022-2461

Source： Journal of Materials Science, Vol.40, Iss.19, 2005-10, pp. : 5153-5159

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Abstract

Surface-welds of Hastelloy C4 and some mixed welds of Inconel 600 and Hastelloy C4 were prepared by the plasma-hot-wire-surface-welding method. Intercrystalline corrosion tests were performed in a diluted Streicher-solution. On-line recording of the corrosion potential uses the stability of the redox-pair, Fe(III)/Fe(II) (called the chemical potentiostat). Microscopic observations of specimens after corrosion accompanied the potential recording and gave valuable information about the morphology changes that occur due to intercrystalline corrosion.Potential measurements in a 1/3-diluted Streicher-Test solution showed that 2-layer surface-welds of Hastelloy C4, prepared by the hot-wire-surface-welding method with arc-deflection, were the most resistant to intercrystalline corrosion. A mixed 2-layer surface-weld of Inconel 600 inner-layer and Hastelloy C4 outer-layer was not effective due to the heterogeneous interface formed between both layers.