Chromium Free Nickel Alloys for Hot Sulfuric and Sulfur Environments
High Si alloys are recognized to have excellent corrosion resistance, especially in mineral acids, but are usually brittle due to compound formation. Nickel silicide, Ni3Si is one compound that has improved ductility through a combination of micro and macro alloying. Nb and Si have been added to create a patented cast alloy with excellent corrosion resistance to sulfuric acid and good mechanical properties. In this paper, efforts to optimize the alloys performance are presented along with progress toward the development of a wrought version of the material. It was found that an appropriate heat treatment provides the largest improvement in the cast Ni-Si alloys' microstructure. The identification of G phase as a detrimental phase has lead to efforts to eliminate or make innocuous this factor. Trials have resulted in more than a 50% reduction by the cold rolling process. This process not only increases homogenization but also results in a decreased area fraction of G phase with a more uniform distribution, which should be beneficial for both improvements in ductility and corrosion resistance.
J. W. Newkirk et al., "Chromium Free Nickel Alloys for Hot Sulfuric and Sulfur Environments," Proceedings of the 138th TMS Annual Meeting and Exhibition (2009, San Francisco, CA), vol. 2, pp. 189 - 196, Minerals, Metals and Materials Society (TMS), Feb 2009.
138th TMS Annual Meeting and Exhibition (2009: Feb. 15-19, San Francisco, CA)
Materials Science and Engineering
Keywords and Phrases
Area Fraction; Cast Alloys; Chromium-Free; Cold Rolling Process; Compound Formation; Excellent Corrosion Resistances; G Phase; High-Si Alloys; Micro and Macro; Mineral Acid; Ni-Si Alloy; Ni-Si-Nb; Nickel Silicide; Sulfur Environments; Uniform Distribution; Acid Resistance; Acids; Chromium; Cold Rolling; Corrosion Resistance; Ductility; Functional Electric Stimulation; Mechanical Properties; Microcrystalline Silicon; Nickel; Nickel Alloys; Niobium; Silicides; Silicon; Sulfur; Sulfur Compounds; Sulfuric Acid; Silicon Alloys; Cold Rolling; Corrosion; G Phase; Ni-Si-Nb
International Standard Book Number (ISBN)
Article - Conference proceedings
© 2009 Minerals, Metals and Materials Society (TMS), All rights reserved.
01 Feb 2009