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The “C” family of Ni‐Cr‐Mo alloys' partnership with the chemical process industry: The last 70 years
Author(s) -
Agarwal D. C.,
Herda W. R.
Publication year - 1997
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19970480810
Subject(s) - alloy , metallurgy , corrosion , 6111 aluminium alloy , crevice corrosion , materials science , 5005 aluminium alloy , stress corrosion cracking , pitting corrosion , oxidizing agent , chemistry , organic chemistry
The “C” family of alloys, the original being Hastelloy® alloy C (1930's) was an innovative optimization of NiCr alloys having good resistance to oxidizing corrosive media and NiMo alloys with superior resistance to reducing corrosive media. This combination resulted in the most versatile corrosion resistant alloy in the “NiCrMo” alloy family, with exceptional corrosion resistance in a wide variety of severe corrosive environments typically encountered in CPI and other industries. The alloy also exhibited excellent resistance to pitting and crevice corrosion attack in low pH, high chloride oxidizing environments and had virtual immunity to chloride stress corrosion cracking. These properties allowed this alloy to serve the industrial needs for many years, although it had some limitations. The decades of the 1960's (alloy C‐276), 1970's (alloy C‐4), 1980's (alloy C‐22 and 622) and 1990's (alloy 59, alloy 686 and alloy C‐2000) saw newer alloy developments with improvements in corrosion resistance, which not only overcame the limitations of alloy C, but further expanded the horizons of applications as the needs of the CPI became more critical, severe and demanding. Today the originally alloy “C” of the 1930's is practically obsolete except for some usage in form of castings. This paper presents a chronology of the various corrosion resistant alloy developments during this century, with special emphasis on the last 70 years evolution in the “C” family of NiCrMo alloys and their applications.