UPPER BAINITE - LOWER BAINITE
UPPER BAINITE - LOWER BAINITE
(OP)
What is the most appropriate method for differentiating upper bainite from lower bainite ? Is light microscopy able to do it via special etching such as SMB (sodium metabisulfite) and / or picral ? Is the use of polarizing filters and sensitive-tint plate going to help ? Material to be checked is 4340 liquid quenched and tempered.
Thank you.
Thank you.





RE: UPPER BAINITE - LOWER BAINITE
lower and upper bainite are distinguishable by the size of the structure. Use a good brightfield scope, a 550nm (green) filter might help bring the contrast out, Nital etch.
nick
RE: UPPER BAINITE - LOWER BAINITE
RE: UPPER BAINITE - LOWER BAINITE
I also think that the lower bainite will be the finer structure.
nick
RE: UPPER BAINITE - LOWER BAINITE
Picral is also a reccomended etch from Metals handbook 9th edition.
nick
RE: UPPER BAINITE - LOWER BAINITE
RE: UPPER BAINITE - LOWER BAINITE
http://www.metallograf.de/start-eng.htm
RE: UPPER BAINITE - LOWER BAINITE
Interesting web site - I better brush up on my German.
RE: UPPER BAINITE - LOWER BAINITE
The webmaster appears to translating more everytime I've visited the site.
They respond in English so there is hope.
unclesyd
RE: UPPER BAINITE - LOWER BAINITE
As for lower bainite, it would be more regular needlelike shape. The temp for lower bainite to form is around 200-300 deg C.