Damaging HT of CPM M4

t1mpani

t1mpani

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Joined
Jun 6, 2002
Messages
5,526
Quick question here,
I recently picked up a Spyderco Gayle Bradley with a CPM-M4 blade and I love the thing. Since I carry clipped folders IWB, and non-stainless knives riding that close to the body can suffer somewhat from it, and I'm sending some guns off to Springer Precision for Ion Bond (DLC) coating anyway, I thought I might send the blade along to get DLC coated too. The guy from Springer said they would be happy to do it, and that the temperatures reached during the process would range from 350-400 degrees, F. Would this likely affect the heat treatment? I know Ion Bond coats Spartan's blades for them, but I also wonder if very thin flat- ground CPM M4 might react differently than thick, saber-ground S30V, since the latter can sink the heat more easily, and I know different steels have heat tolerances. Or, am I worrying about nothing? :)

Thanks much,
Warren
 
It seems unlikely you'd have any effect on the HT. IIRC M4 is a High-Speed-Steel, formulated to maintain its hardness at high temperatures. The CPM version may have some minor tweaks to the composition, but it should still be basically M4.

http://www.suppliersonline.com/propertypages/M4.asp

gives some detail on M4 including "Tempering Temper at 1050 F for a Rockwell C hardness of 62 to 66."

I don't think a relatively gentle 400 degF is going to hurt any.
 
Thanks, you two. The fact that it is a high speed steel had occurred to me and I figured it'd probably be okay, but also figured it was silly not to use the excellent resource that is this forum. Thanks again. :)
 
Here is a chart showing the austenitizing/tempering information:

CPMM4-TC.gif
 
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