Tempering 440C to Obtain Properties of 440A

[MechyMarco]

Hi all,

Problem: Parts made out of 440C are too brittle. Need more toughness and ductility. Current parts are tempered at 600F to HRC 56.

Solution: Re-heat treat to reduce hardness and obtain increased toughness and ductility. Using 440A as reference. Shooting for HRC of 51.

Question: Is it a fair assumption to assume tensile strength of new 440C reduced hardness HRC 51 will be similar to 440A tempered at 600F to HRC 51? What about the other material properties like Red. of Area and Elon. in. 2 in? The current method to the madness is applying a linear extrapolation using the ASM data for tensile strength vs hardness.

I know this isn't the ideal way of going about things, but I'm stuck with these parts and would like to find a way to optimize the strength to toughness balance by playing with the hardness. The next batch will be 440A.

Thanks!

Calgary, AB
Mechanical Design Engineer

 

[EdStainless]

https://www.atimetals.com/Documents/ati_410_420_425_mod_440a_440c_tds_en4_v2.pdf

http://cartech.ides.com/datasheet.aspx?i=103&e=72

You may have to go to 900F or 950F in order to get the material down to your normal hardness.
Even then I would expect the 440C to be less ductile than the 440A, but that isn't saying much.
This will take some trial and error.


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P.E. Metallurgy, Plymouth Tube

 

[metengr]

http://www.crucibleservice.com/eselector/prodbyapp/stainless/cru440cs.html

The higher carbon 440C is going to give you problems with poor ductility and toughness in response to tempering when compared with the lower carbon 440A. I am not sure you will achieve what you think you need from the 440C. Carbon is such a potent strengthening agent for the 4xx stainless steels.

 

[MechyMarco]

Thanks for the replies. I figured it would come down to trial and error on this one. I'll let you know how the testing goes.

Cheers.

Mechanical Design Engineer