In my experimental alloy I want to calculate the actual critical temperatures of alloy steel like ac1.ac3.Bs. Bf, Ms,Mf,liquidus and solidus temperature by TMS GLEEBLE 3800.This will help me in selecting proper heat treatment temperatures to get best static and dynamic mechanical properties.Request fellow researchers working on TMS and Dilatometer for similar work to kindly send me sample size and experimental details.
Critical temperatures are used for both for designing hot deformation processes, like hot rolling, forging as well as heat-treatment. However, there is a big difference between critical temperatures experienced during hot deformation and heat-treatment. This is primarily due to strain which significantly affects transformation temperatures, particularly on-cooling.
Empirical equations available in references does not take care of strain and therefore, these are not applicable to hot deformation processes but these may be used for heat-treatment purpose.
As for as determination of these temperatures are concerned, Gleeble can very well be used for this purpose. This will be more realistic and close to actual situation.
It is not that empirical equations can serve only as a broad guideline as these have been evolved using certain set of alloys. The output may not be applicable if the input is beyond this range.
Dear Shivraj,
I agree with Michael, the Gleeble can be fitted with a dilatometer unit, but using a Dilatometer is better.
You can also search the literature (or RG) for equations for determining critical transformation temperatures, which is useful for quick comparisons of different compositions/alloys.
ThermoCalc can also be used to find liquidus and solidus temperatures, and equilibrium transformation temperatures.
Regards,
Kristin
See attached for Ms and Bs empirical equations. You will get a lot of useful references from it. For dilatometer, the hollow cylinder sample is prefered, such as 5 mm outer diameter, 3.5 mm inner diameter and 10 mm length. The exact dimension depends on the type of dilatometer. Have a check with the technician.
Critical temperatures are used for both for designing hot deformation processes, like hot rolling, forging as well as heat-treatment. However, there is a big difference between critical temperatures experienced during hot deformation and heat-treatment. This is primarily due to strain which significantly affects transformation temperatures, particularly on-cooling.
Empirical equations available in references does not take care of strain and therefore, these are not applicable to hot deformation processes but these may be used for heat-treatment purpose.
As for as determination of these temperatures are concerned, Gleeble can very well be used for this purpose. This will be more realistic and close to actual situation.
It is not that empirical equations can serve only as a broad guideline as these have been evolved using certain set of alloys. The output may not be applicable if the input is beyond this range.
Thank you very much Dr. Vinod for your valuable answer , I need these critical temperatures for some alloys to redesign my HT cycles and thermo-mechanical process like forging and rolling to ensure proper recrystallization and final grain size.
Regards
Shivraj
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