Nitronic

Nitronic is the trade name for a collection of nitrogen-strengthened stainless steel alloys. They are austenitic stainless steels.

For the nitronic acid functional group, see Nitronate.

History

Nitronic alloys were developed by Armco Steel. The first of these alloys, Nitronic 40, was introduced in 1961.[1] Since 2000, the trademark has been owned by AK Steel, successor to Armco Steel.[2] Electralloy is the licensed producer in North America for a wide range of Nitronic products.[3]

The Nitronic name is due to the addition of nitrogen to the alloy, which enhances the strength internally rather than being nitrided on the surface, as some steel are treated. The nitrogen is homogenous throughout the material. Nitronic materials have about twice the yield strength of 304L and 316L.[4]

Uses today

Nitronic 30 is used to lighten transportation vehicles.[5] Buses and railcars benefit from the high strength-to-weight ratio for energy savings, with less steel used for the application. Nitronic 40 is used in the aerospace industry as hydraulic tubing.[1] Nitronic 40 has unusually good performance characteristics at ultralow temperatures, which offers a "design advantage" over comparable alloys.[6] Nitronic 50 is used in marine environments, including boat shafting and solid rod rigging.[7] Nitronic 60 and a similar alloy Gall-Tough were specifically developed to have superior resistance to galling, a form of wear caused by adhesion between sliding surfaces, and metal-to-metal wear.[8]

Composition

Nitronic alloys have widely varying compositions, but all are predominantly iron, chromium, manganese and nitrogen.

NITRONIC Element (% by mass)
Fe Cr Ni Mo Nb Mn Si C S P V N
30 UNS S20400

[9]

 Bal 15.0–17.0 1.5–3.0 7.0–9.0 1 max 0.03 max 0.03 max 0.04 max 0.15–0.3
32 UNS S24100

[10]

 Bal 16.5–19.0 0.5–2.5 11.–14.0 1 max 0.15 max 0.045 max 0.2–0.45
33 UNS S24000

[11]

 Bal 17.0–19.0 2.3–3.7 11.5–14.5 0.75 max 0.08 max 0.01 max 0.06 max 0.–0.4
40 UNS S21900

[12]

 Bal 19–21.5 5.5–7.5 8.0–10.0 1 max 0.04 max 0.01 max 0.04 max 0.2–0.4
50 UNS S20910

[13]

 Bal 20.5–23.5 11.5–13.5 1.5–3.0 0.01–0.03 4.0–6.0 0.2–0.6 0.03 max 0.01 max 0.04 max 0.1–0.03 0.2–0.4
60 UNS S21800

[14]

 Bal 16–17 8.0–8.5 0.75 max 0.10 max 7.5–8.5 3.7–4.2 0.06–0.08 0.03 max 0.040 max 0.2 max 0.1–0.18

References
  1. Harold M. Cobb (2010). The History of Stainless Steel. p. 305. ISBN 9781615030118. Retrieved March 19, 2017.
  2. AK Steel GB (2011–2017). "About us". p. 1. Retrieved March 17, 2017.
  3. "When your application is critical, when there is no room for error, your choice is Electralloy". Electralloy. 2017. Electralloy is North America's exclusive licensed producer of all NITRONIC® bar, billet, coil rod, master alloy pigs and ingot products as well as NITRONIC® weld wire and weld consumables.
  4. C. G. Fountzoulas; E. M. Klier; J. E. Catalano (2016). Dan Casem; Leslie Lamberson; Jamie Kimberley (eds.). Dynamic Behavior of Materials, Volume 1: Dynamic Characterization of Nitronic 30, 40 and 50 Series Stainless Steels. p. 22. ISBN 978-3319411323. Retrieved March 19, 2017.
  5. Bruce Emmons (June 27, 2016). "Ultralight Electric Bus". p. 1. Retrieved March 19, 2017.
  6. Di Giovanni, Mario (1982). Flat and Corrugated Diaphragm Design Handbook. CRC Press. p. 42. ISBN 9780824712815.
  7. Dan Spurr (Jan–Apr 1982). "Cruising World". p. 68. Retrieved March 19, 2017. Cite magazine requires |magazine= (help)
  8. Davis, Joseph R. (2000). Alloy Digest Sourcebook: Stainless Steels. ASM International. p. 3. ISBN 9780871706492.
  9. AK Steel. "Nitronic 30 Stainless Steel" (PDF). Retrieved March 19, 2017.
  10. Electralloy. "Nitronic 32 Stainless Steel" (PDF). Retrieved March 19, 2017.
  11. Electralloy. "Nitronic 33 Stainless Steel" (PDF). Retrieved March 19, 2017.
  12. Electralloy. "Nitronic 40 Stainless Steel" (PDF). Retrieved March 19, 2017.
  13. Electralloy. "Nitronic 50 Stainless Steel" (PDF). Retrieved March 19, 2017.
  14. Electralloy. "Nitronic 60 Stainless Steel" (PDF). Retrieved March 19, 2017.
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