Induction Hardening for Low Carbon Steel 3

[alliedtrans]

Hello

I wanted to know whether 20MnCr5 with some modifications can be hardened through Induction Hardening. So basically can a low carbon steel be hardened through induction?

Regards
Ankur

 

[CoryPad]

Yes it is possible to use induction heating plus quenching to harden 20MnCr5. The maximum hardness will be less than 45 HRC.

 

[swall]

Alliedtrans--you do understand that the results will not be comparable to carburized 20MnCr5, don't you?

 

[alliedtrans]

I know that the results will not be comparable but the items I am talking about are synchronizer components for a gearbox and some manufacturers have been using induction with changed alloy steel chemistry to fasten their production. Hence I wanted to know if it can be done and some details as to how.


Thanks
Ankur

 

[TheBlacksmith]

Addition of surfactants to the quench water to prevent steam blanketing of the parts aids in hardening low carbon steel.

 

[alliedtrans]

Thanks TheBlacksmith for your reply.. i had heard something of the same nature.. Can you please let me know which surfactant to add to water for hardening 20MnCr5 to achieve a hardness of 50-53 HRC.

 

[BrianPetersen]

I don't think you are going to get it that hard unless the steel has a bit higher carbon content, no matter what you try.

 

[swall]

Yes, look at CoryPad's response.

 

[TVP]

In order to quench to 50-53 HRC, the steel needs to have an absolute minimum C content of ~ 0.25%, and more like 0.27%. 20MnCr5 just doesn't have sufficient C content even at the upper end of the spec. The two closest grades that are standard in the European system are 30MnB5 (1.531) and 27MnCrB5-2 (1.7182) according to EN 10083-3. In the +H condition, they have maximum hardenability of 55 HRC up to 5 mm from the quenched end in a Jominy test. So, for thin rings and composition restricted to the high end of the hardenability range, you could water quench after induction heating and achieve hardness > 50 HRC. The water temperature would need to be relatively low as well as the polymer concentration, which means cracking and distortion are more likely.