Vdm Nickel-Technologie Aktiengesellschaft

Manfred Rockel

Ulrich Heubner

Michael Kohler

Ernst Wallis

Rolf Kirchheiner

For use in making components which are required to have a very high resistance to uniform corrosion and against pitting and crevice corrosion under very highly corrosive conditions encountered in up to date chemical process technology and environmental protection technology, for instance, in flue gas desulfurizing plants for concentrating sulfuric acid, and which are required to be manufactured satisfactorily by conventional hot and cold forming processes an alloy is employed which contains (in % by weight) 22.0 to 24.0 chromium, 15.0 to 16.5 molybdenum, up to 0.3% tungsten, up to 1.5% iron, up to 0.4% vanadium, 0.1 to 0.4% aluminum, 0.001 to 0.04% magnesium and 0.001 to 0.01 calcium, balance nickel and inevitable accompanying elements and impurities.

Corrosion resistant hot and cold forming parts of Ni-Cr-Mo alloy and

Disclosed in an improvement in a known Ni-Cr-Fe alloy. The alloy of the invention contains 30 to 32% nickel; 26 to 28% chromium; 0.5 to 1.5% copper; 6 to 7% molybdenum; up to 2% manganese; up to 1.0% silicon; up to 0.2% aluminum; up to 0.03% carbon; 0.10 to 0.25% nitrogen; balance iron and usual impurities. The alloy of the invention has increased pitting corrosion potential and critical crevice corrosion and pitting corrosion temperatures whereas the resistance of the alloy to commercially pure phosphoric acid has not been decreased.

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Friedrichsdorf, Germany

Manfred Rockel