High-chromium alloy resists sulphuric acid at high heat

Citation

(1999), "High-chromium alloy resists sulphuric acid at high heat", Anti-Corrosion Methods and Materials, Vol. 46 No. 1. https://doi.org/10.1108/acmm.1999.12846aad.008

High-chromium alloy resists sulphuric acid at high heat

High-chromium alloy resists sulphuric acid at high heat

Keywords Alloys, Corrosion, Krupp VDM, Oxidation

An alloy specifically designed to resist corrosion when exposed to severely oxidizing media such as highly concentrated sulphuric acid has reportedly been developed by Krupp VDM, Germany. Nicrofer 3033-alloy 33 is a high-chromium alloy within the chromium-iron-nickel system, with nitrogen added to stabilize the austenitic lattice, and molybdenum (1.6 per cent) as well as copper (0.6 per cent) added for overall improvement in corrosion resistance.

Solution-annealed at 1,120°C, the alloy has a homogeneous, fine-grained microstructure. It is said to have good processing and welding characteristics, with high resistance to pitting and crevice corrosion in chloride-containing media, as well as in hot mineral acids of HNO₃/HF (pickling solutions) and alkalis. It is also highly resistant to stress-corrosion cracking. For welding, consumables of matching chemical composition are usually selected.

Applications to date include plate-type heat exchangers for heat extraction from 96-98.7 per cent H₂SO₄ at 100°C (212°F); manufacture of a 6.5m³ (230ft³) mixing vessel for the chemical industry; and components for the paper and pulp industry. The company is currently working with an industrial partner, testing the material for cast pump housings.

Details from: Krupp VDM GmbH, Offentlichkeitsarbeit, Plettenberger Strasse 2, D-58791 Werdohl, Germany. Tel: +49 (023 92) 55 0.