Overheat 440C while grinding?

T

tom2

Joined
Feb 2, 1999
Messages
29
I'm just a newbie starting to grind my first blade and have a few questions. When grinding, I sometimes overheat the steel and "burn" it. Will this affect the heat treating? Secondly, I'm planning to grind my blade on one side only. I'm using precision ground stock but am concerned that heat treating might warp the blade due to the one sided grind. Should I be concerned?

Thanks in advance, this forum is great!
 
I'm NOT a maker, and I hope Alan Folts stops by this thread (he IS). Or other makers. But every source I've heard from says that 440C, ATS34 and some other "high tech alloy stainlesses" are a "one shot only" heat-treating proposition. Some aren't, like 440B which is why Randall uses it in a "heat'n'beat" forging process.

Meaning, if you "burn" 440C at the grinder you've used up your "one shot" at heat-treating...not good.

Now, I doubt that's what you wanted to hear. I *suspect* that the "burned area" isn't too deep and you can make it a hair thinner but still sound...but that's theory from the inexperienced, we need a more solid opinion in here.

I know Alan Folts talked about grinding my 24" ATS34 sword with bare hands so he could feel the heat in the steel before things burned...and how key that is to long-term performance.

Jim March
 
Any air hardening steel will be adversely affected by heating into the "red" or "dull red" zone during grinding. Discoloration in general (400-600F) during rough grinding isn't a problem, although it's best to cool the blade frequently during grinding. After heat treatment, if you overheat it at all, you're done. Yes, If you heat-stress an unsymmetric grind, you are apt to experience warpage during heat treatment, and end up with something resembling a potato chip..
My advice is , learn to work without gloves-I never wear them. Grind slowly, and use that water bucket OFTEN. Also, think seriously about grinding blade bevels using only brand new, sharp belts, both before and after heat treatment. Run the belt more slowly, also. This cuts down on the heat. Generally, slow down.
You could try heat treating your blade, but, I'd suggest scrapping it and starting over.

Good Luck,
RJ Martin
 
gee whiz...took forever for this thing to load...anyhow...back in the early 80s when i was just starting to make knives i proposed this very question to bob loveless in his shop (glenn hornby took me over there) and again to bob engnath the next day...i had heard that you could burn the carbon out of hi carbon steel by overheating it again and again...if you have ever seen either of these guys grind....they just laughed...they Both LEAN HARD on the blades with a 40,50 or 60 grit belt.....red hot is an understatement/ you dont have to worry about that...believe me...i get my blades cherry red constantly....and they are used hard by lots of people that go hunting every weekend, bash rocks, etc, the thing that you have to worry about is proper heat treat, and like the other guy said, even grind, whenever i make a sashimi knife with a one side grind, especially if its hollow ground on only one side, it warps....also, when you get the knife cherry red when youre grinding dont quench it suddenly into water or whatever...sets up rad stresses....440c is hardened at almost 2000degrees...getting it hot wont hurt it...i guarantee it....18 years of doing it....tom mayo...
 
post script...i was talking about pre heat treat grind of course.....after heat treat i always hold them in my bare hands.....tom
 
Thanks for all the good info. I guess its a good thing (?) I'm using a 1" x 30" inexpensive grinder. If I push it too hard, it just stalls....

I wonder if I can convince the wife that I need a Burr King? ;-)
 
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