-- The Home Page of the Finishing Industry

on this site
current topics

60,000 Q&A topics -- Education, Aloha, & Fun

topic 8832

Oxidation of carbon steels at temps between 500-600'C


I'm interested in getting info on the oxidation or "bluing" of carbon steels at temps around 500-600 'C. A few specific questions I have:

1. is it just a surface effect?
2. does the oxidized metal differ in electrical conductivity from the base metal?
3. what forms the oxide (chemical composition)?
4. in my application the oxidized steel will be in contact with liquid lithium. what is the chemical compatibility between this oxide and lithium metal?

Any additional information is welcome.

Tom Neirynck
Fermi National Accelerator Laboratory - Batavia, Illinois, USA


There are three forms of oxide that form on steel when the metal surface is exposed to oxygen at elevated temperature: Wustite (FeO), Magnetite (Fe3O4) and Hematite (Fe2O3). Only magnetite and hematite can form below 570C. The scale formed below 570 will grow slowly and be primarily magnetite with a thin surface layer of hematite. Oxidation will progress more rapidly at higher temperatures. Above 570, the oxide layer will consist of about 95% wustite, 4% magnetite and 1% hematite in layers formed in that order from the substrate. Some wustite may transform to magnatite and hematite during slow cooling.

There is a detailed discussion of oxidation with pictures in the book, Light Microscopy of Steels by L E Samuels (published by ASM International).

larry hanke
Larry Hanke
Minneapolis, Minnesota


Dear Mr.Neirynck:

I would like to know: What difference in colour would two steel surfaces show when viewed at room temperature if one is exposed to oxygen at temperatures below 570 degrees C and the other at or above 570 degrees C?


Mr. Wilmer Urbano
- Punto Fijo, Edo. Falcon, Venezuela

this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start NEW Thread

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental Compliance

©1995-2020, Inc., Pine Beach, NJ   -   About   -  Privacy Policy
How Google uses data when you visit this site.