Temper Color Question

GibsonFan

GibsonFan

Joined
Jul 7, 2006
Messages
2,526
Tried my hand at tempering a file knife in the oven last night. The knife was all ground and ready for hand-rubbing. The oven was preheated to 400 (or so it said) from making dinner, so I turned it down to 350 and popped in a file knife for an hour. Or so... there was beer involved...

Anyway I took it out and was pleased to see a nice light straw color on it. I didn't file test it because, well, it was hot! Not having a proper place to put it, I threw it in the freezer and promptly forgot about it.

So anyway this morning, the color has deepened to a dark bronze. How come?

It seems to have worked nicely. The steel scratches easily with a file of the same type. The edge flexes against a brass rod, but comes back into alignment on its own. No chipping at all. I'm just curious if the color would have darkened like that anyway, or the time in the freezer had anything to do with the results at all. Regardless I'm pretty pleased!

Thanks guys, I wouldn't have gotten this far without your help and encouragement! :)
 
Temper colors are oxides and dependant on temperature , alloy and surface condition [ oil etc]
 
I just picked up some finer grit paper (up to 1200) and will putter around hand-rubbing it this weekend. Should have some idea about the edge tomorrow night or so.

I'll have to do some reading on cryo; I'm still curious if the freezer time helped any. Have to make another one the same way but not use the freezer, and compare 'em I guess.
 
IF you got a bronze color I would say it is around 60 on a harden tester. I like when it comes out with the gold or bronze color most of my tests I get 59-60 1/2 and that on the money in my book for a using knife. Sounds like you did at great job. If you can check the hardens on the steel and see what it is, and let me know. Thanks for posting.
 
GibsonFan said:
I just picked up some finer grit paper (up to 1200) and will putter around hand-rubbing it this weekend. Should have some idea about the edge tomorrow night or so.

I'll have to do some reading on cryo; I'm still curious if the freezer time helped any. Have to make another one the same way but not use the freezer, and compare 'em I guess.
Click to expand...

I hate to be the proverbial stick in the mud, but chances are that putting the blade in the freezer was of little or no benefit. Temps for getting retained austenite to kick over to martensite need to be much lower than a household freezer can get. Not sure what kind of steel you used, but if it's not stainless, I wouldn't even worry about the retained austenite factor too much. That's just my take on the matter, I could be wrong though! -Matt-
 
Barkes Knife Shop said:
IF you got a bronze color I would say it is around 60 on a harden tester. I like when it comes out with the gold or bronze color most of my tests I get 59-60 1/2 and that on the money in my book for a using knife. Sounds like you did at great job. If you can check the hardens on the steel and see what it is, and let me know. Thanks for posting.
Click to expand...

The only testing I've done so far is the brass rod test. Obviously this is kind of subjective but the results I've gotten make sense. Based only on this, the file blade is "better" than my Becker Necker, becasue the Necker's edge flexes and retains SOME of the flex. Which straightens right out with a few strokes on an arkansas stone. I should point out that I like my Necker very much, it's a darn good cutter and sharpens easily. I wish I had had the sense to test the file knife this way before I baked it, for comparison's sake :foot:

I don't have access to any real testing equipment. I'll just use it the way I use everything else, and sharpen it with the same stones. That should give me a good clue. I didn't do a great job, I just did some reading and got plain lucky!

grease-man said:
I hate to be the proverbial stick in the mud, but chances are that putting the blade in the freezer was of little or no benefit.
Click to expand...

I think you're right, grease-man. The freezer wasn't really anything but somewhere to store it as it cooled off.
 
Yeah, but if I lay mine on the bench I'm liable to grab it and scorch my guit-pickin' callouses. Trust me, I know how much of an idiot I can be, and I've learned to adapt to it :D
 
You must log in or register to reply here.
Back
Top