Carburized Austenitic Stainless Steel

[Montana1]

I was reading an API document regarding inspection for austenitic stainless steel heater tubes. It stated that carburized areas of 300 series tubes will have magnetic properties. Can anyone explain this to me on a metallurgical level?

 

[metengr]

Go here
Appearance of carburization-induced magnetism is the result of decrease of chromium in matrix due to formation of chromium carbides. ...

http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5393467

- 12k

 

[EdStainless]

Actually lowering the Cr content should make the alloy less likely to be magnetic. However it raises the Curie temp enough that those regions will be magnetic at room temp.

http://www.ndt.net/article/wcndt2004/pdf/materials_characterization/314_kamada.pdf

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