Evolution of the grain size during quenching and tempering 1

[stanislasdz]

Maybe it'stupid question !!!! but i want to know if during quenching and tempering the grain size change in steel forgings or castings.

If yes : what are the most important factors :

(quanching media, austenization temperature, thickness of the part and so on ...)

Thanks

 

[redpicker]

The answer really depends on what you mmmmean by grain size.

Typically, for steels, we refer to the prior austenite grain size, which refers to the size of the austenite grains that existed prior to cooling from austenitizing temperature. This can be affected by several factors, mainly melting practice, chemistry, austenization temperature and time, amount of forging reduction (for wrought products) or solidification rate (for castings). Quenching media has little affect on the prior austenite grain size. Part thickness can have a secondary effect since it can affect the temperature, time at temperature, as well as a tertiary effect by perhaps reflecting forging reduction or solidification rate.

For low-carbon steels, there is a ferrite grain size which can be affected by cooling rate as well as the above factors.

rp

 

[stanislasdz]

Great thank you !!!!