The effect of the temperature realese after quenching on steel parts 1

[stanislasdz]

Iwould like if anyone can explain me what is the effect of
the temperature release after quenching.

Exemple :

i perform a quench of a casting or forging in the oil ?

What is the best final part temperature to extract this part :

100°C, 80°C? 50°V , RT ?

Thanks !

 

[arunmrao]

As low a temperature as possible,would be ideal. But more important is to immediately start tempering,if this is not possible atleast a low temperature stress relieving is always advised. What is the alloy, component and weight of the part.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[stanislasdz]

thanks arunmrao, but what is the metallurgical explanation of the difference if you extract a part at 20 °C 50 or 80 °C ?

 

[redpicker]

It really doesn't make much difference as long as you are below the martensite finish (Mf) temperature. Depending on the steel composition, this can be from around 280C to below room temperature.

For most low-alloy medium carbon steels, you are probably looking at a Mf of around 200C. Going below the Mf does not do any good and only increases the likelihood of cracking.

Keep in mind that this would refer to the core temperature, not the surface temperature. But, if the steel has a Mf of 230 C and you check the surface of a 50 kilo part 5 minutes after removal of the quench and it's below 150C, you're OK.

We routinely aim for a quench exit temperature of around 175 C for a .42%c, 1%Mn, 1%Cr, .3%Mo steel. Most of these parts would crack if they were allowed to cool to below 100C.

 

[stanislasdz]

thanks redpicker !