Case Harden 1018 1

[MechE22]

What were to happen if you tried to case harden a thin (0.010") 1018 steel washer? That depth is obviously obtainable with case hardening however a low carbon steel cannot be through hardened. I'm not sure what extra stresses would occur or whether it is doable.

Thank you,
George

 

[mp87]

By case hardening a low carbon steel you raise the carbon content to that of a high carbon steel, which is indeed through hardenable. With such a small thickness you will end up with an entirely carburised washer and the unbalanced compressive stresses will make it warp just like it happens with the Almen strips during shot peening.

Why not nitrocarburising it? You will get increased hardness in a very thin surface layer and lower distortion.

 

[Tmoose]

What size is this washer ?
How hard does it need to be?

 

[MechE22]

Nitrocarburising would work. I was more just curious to the chemistry/physics of trying to case harden a thin part. Materials science is not a strong facet of my expertise.

The washer is 0.010" thick, OD is 0.225". The reason I thought of case hardening is because there is a pin that contacts the washer (though the ID) that is 1018 case hardened. I wanted to keep the specs the same. There is no reason I even need to use 1018 on the washer.

I am looking for 50+ HRC

 

[mp87]

Ok, I thought there were some other constraints forcing the use of 1018. If this is not the case, you can simply use a medium carbon steel like 4140, 4340. You can easily reach through hardness values above 50 HRC on such a thin part.

 

[EdStainless]

Or use 1040, it is a thin part after all. There is no real reason for the alloy steels.
They might need to be press-quenched in order to keep them flat.

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P.E. Metallurgy, Plymouth Tube

 

[CoryPad]

I would consider using 1050 steel and austempering to 50 HRC, very common for thin steel parts that are sensitive to distortion.

 

[EdStainless]

Good call Corey, that is a better solution.

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P.E. Metallurgy, Plymouth Tube

 

[tbuelna]

Case hardening will not work well with the thin section material described. If you require a .010" thick x .225" OD flat steel washer with Rc50 hardness, you're best option is to start with a thicker washer blank that is through hardened/tempered, and then surface ground to the required thickness/flatness tolerances.