JMatPro software is quite good and easy to use for CCT/TTT calculations.
If you are not able to find this software, you may check "Database for Steel Transformation Diagram" by Steel Data: http://www.steeldata.info/std/std.html
I have just found the link by a google search and haven't any experience on it but it seems there is a demo version on webpage. You may check it if the demo version includes the required diagrams of austenitic stainless steels or not.