View Single Post
  #2  
Old 08-22-2004, 06:19 PM
Quenchcrack Quenchcrack is offline
Steel Addict
 
Join Date: Jun 2004
Location: NW Tennessee
Posts: 167
Triple whammy...

Mike, triple quenching is used to reduce the grain size of the austenite from which the martensite forms, thus improving toughness. It also dissolves more of the carbides, putting more carbon into solution, thus improving hardness. You must use progressively lower tempertures to austenitize so it takes some degree of instrumented control to really do it right. If your target austenitizing temperature is 1500F, quench first from 1600F, then from 1550F, then from 1500F. However, you can eyeball it and do some good. Tempering between quenches is not really necessary but re-heat gently to prevent thermal shock.

Cryo treatment is used to transform any retained austenite to martensite so it is a continuation of your quench. High carbon (.95% and over) responds best to cryo treatment as the retained austenite is caused by high carbon content. 5160 would probably not show any improvement.


__________________
Which is worse; ignorance or apathy? Who knows? Who cares?
Reply With Quote