What Determines the Stability of Austenite

Written by mfm304:

Austenite in stainless steel is meta-stable. So, when it deformed, it transforms to the more stable phase, martensite. This transformation is a function of temperature and degree of deformation.

The stability of the austenite is expressed as the temperature at which 30% deformation (uniaxial tension) produces 50% transformation.

It is related to composition in the following way:

  • Md30©=413-462(C+N)-9.2Si-8.1Mn-13.7Cr-9.5Ni-18.5Mo

Any alloy addition lowers the Md30 and stabilizes the austenite.

@mfm304, Thank you for taking the time to do this write-up on austenite.