Carburizing 1020 steel

[matt037]

Would it be conceivable to expect gas carburized 1020 carbon steel to achieve a case hardness of 15N88 (approximately Rc 56)?

 

[unclesyd]

You can easily get 60-62 Rc with a cyanide bath so 56 Rc should be achievable.

What is the size of the part?

Do you have concerns about the core hardness?

 

[matt037]

We have several parts ranging in size from 3" OD X .8" ID X .7" deep (largest) down to 1" OD X 3/8" ID x 11/32" deep (smallest). We are trying to get away from our current process of ion nitriding 4340 and are looking at a number of options. Achieving the case hardness is the most important aspect and core hardness should not be a concern.

 

[NickE]

I feel there has to be another reason besides case hardness that you are using 4340, that steel easily hardens through on your largest part, and Ion Nitriding is going to gibve you a extremely hard case, though thin.

56HRc is not all that hard, as unclesyd mentions.

 

[dbooker630]

I believe that you should be able to attain the surface hardness with carbonitriding as opposed to straight carburizing, but with the lack of alloying the effective depth will be shallow.

 

[PeterCharles]

Based on past experience with similar specification UK steels you will need to carbo-nitride rather than carburise this steel to get Rc56 (we used to get Rc59-61).

 

[metengr]

We are trying to get away from our current process of ion nitriding 4340 and are looking at a number of options.

I agree with NickE that you had better carefully evaluate the change in material. Case hardness and applicable surface treatments are one consideration, but when you change alloy composition, other parameters need to be considered for the intended service; core mechanical properties and notch toughness (if applicable).

 

[arunmrao]

Ion Nitriding being an expensive process and with few facilities available, many are considering to switch over to conventional case hardened parts. However, this change over needs to be done with caution as surface hardness is not the only criteria as advised by others in this post. Core properties are also to be considered. A candidate material quite often being considered now is 8620,this might make a safe transition to case hardening.

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