Overview
CN7M is a high-nickel austenitic stainless-steel alloy specifically formulated for exceptional corrosion resistance in challenging chemical environments. The addition of molybdenum and copper enhances its resistance to sulfuric acid and various reducing chemicals, while its inherent properties make it suitable for use with dilute hydrochloric acid and chloride salt solutions. CN7M's wholly austenitic structure ensures it remains non-magnetic, even after welding. While this alloy offers excellent machinability for ease of fabrication, it requires solution annealing after exposure to elevated temperatures (800° to 1600° F) to restore optimal corrosion resistance and prevent sensitization. This combination of corrosion resistance, non-magnetic properties, and good machinability makes CN7M a valuable choice for demanding applications in chemical processing and other industries where resistance to aggressive chemicals is crucial.
Typical Uses
Heat exchanger parts, flanges, pickling rolls, pump parts, tank accessories, valve components, and centrifuge parts for chemical processing.
MetalTek Grade
MTEK 20
Poured At:
Carondelet Division, Sandusky International Division, Wisconsin Centrifugal Division, Wisconsin Investcast Division
Similar Specifications
Cast UNS: N08007
Wrought UNS: N09020
Wrought Grade: 20Cb-3®
Cast Grade: CN7M
Cast ASTM: A351, A743, A744
Typical Chemical Composition (% by wt.)
Aluminum: n/a
Carbon: 0.07
Chromium: 19-22
Manganese: 1.5
Iron: n/a
Copper: 3.0-4.0
Nickel: 27.5-30.5
Lead: n/a
Tin: n/a
Silicon: 1.5
Zinc: n/a
Other: Mo 2-3
Minimum Mechanical Properties
Heat Treatment: Solution Anneal
Frequently Asked Questions
Super austenitic steel is a high-alloy stainless steel with enhanced levels of chromium, molybdenum, and nitrogen, providing superior resistance to chloride-induced corrosion.
Used in desalination plants, offshore platforms, chemical processing, marine equipment, and pulp & paper industries where high chloride or acidic environments are present.
Super austenitic steels offer higher molybdenum and nitrogen levels than standard austenitic steels, improving their resistance to pitting, crevice, and stress corrosion.
Benefits include exceptional resistance to aggressive environments, high strength, extended life in chloride-rich applications, and suitability for welding and fabrication.
Its high levels of molybdenum, chromium, and nitrogen promote the formation of a passive oxide layer that protects against localized and general corrosion.
Grades such as 254SMO and AL-6XN are considered super austenitic stainless steels, offering premium corrosion resistance in extreme environments.
