Proper callouts for heat treating 4340
Proper callouts for heat treating 4340
(OP)
Hi all,
I am making some 4340 components that need to be 46 - 50 HRC when done, what callout do I give the heat treater?
I am making some 4340 components that need to be 46 - 50 HRC when done, what callout do I give the heat treater?





RE: Proper callouts for heat treating 4340
These need to be discussed with the heattreater along with the designer before releasing the sheet.
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RE: Proper callouts for heat treating 4340
RE: Proper callouts for heat treating 4340
FYI, part is a complex configuration with several deep (.3 in) pockets and webs, there are generous radii in both the floor and sides of the pockets, and yes, I am concerned about cracking.
Another question, what is the maximum hardness / toughness area for this material?
Am I in the right range?
The component will see severe duty in high speed automotive applications.
Thanks
RE: Proper callouts for heat treating 4340
RE: Proper callouts for heat treating 4340
RE: Proper callouts for heat treating 4340
Tempering at 450C will give you about 40 HRC.
RE: Proper callouts for heat treating 4340
According to AMS-H-6875, 4340 can reach 200-220 KSI (43-46C) with an 850F tempering.
If you really have to have those hardness numbers, it might be a safer bet to switch to a different alloy material that can reach those numbers nominally.
If I were in the decision loop, I wouldn't hesitate recommending Hy-Tuf Vacuum Melt. This material will easily achieve 220-240 KSI, which is what you are asking for.
That is just my too cents.
Rob
RE: Proper callouts for heat treating 4340
Upon quenching, 4340 can have a hardness of 60 HRC. You reheat to a certain time-temperature window to "temper" the material to a lower hardness (that also brings out higher toughness/ductility).
Regards,
Cory
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RE: Proper callouts for heat treating 4340
RE: Proper callouts for heat treating 4340
Should be able to get to 48 without cracking.
RE: Proper callouts for heat treating 4340
Please come back with your results. Good Luck!
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