Super Hard Blade

Tom Militano

Tom Militano

KNIFE MAKER
I just ordered a set of the hardness testers that one of our members is selling. I just heat treated and did two temper cycles on three blades, all cut from the same piece of bar stock, 154CM by the way. Two of them came out fine, but one of them is harder than a woodpeckers lips. It came out of the stainless wrap almost entirely blue. The temper cycles didn't help at all. I've never had that happen before. Any ideas?
 
Tom Militano said:
I just ordered a set of the hardness testers that one of our members is selling. I just heat treated and did two temper cycles on three blades, all cut from the same piece of bar stock, 154CM by the way. Two of them came out fine, but one of them is harder than a woodpeckers lips. It came out of the stainless wrap almost entirely blue. The temper cycles didn't help at all. I've never had that happen before. Any ideas?
Click to expand...

where was it sitting, in relation to the other knives in the oven ?
 
In the middle of the three blades. All were sitting on a slotted fire brick with a space between them. I have an 18" deep Evenheat oven. Each one was wrapped individually in stainless heat treating wrap.
 
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I have no ideas on your problem, but would like to know more about these hardness testers.
 
I am just taking a big guess here as I don't know for certain as I am still learning.

It is possible that it took and held more heat being sandwiched between the other blades especially if they were too close together.perhaps the radiant heat of the two blades on either side caused the center blade to actually reach a hotter temperature than was programmed. I assume you are using some kind of a stand/rack to hold the blades in an upright position. How close together are the blades in your rack?

Have you done more than two blades at a time before?

Have you had this to happen before?

JDW, I am not for sure but I think what he is talking about is this thread,
http://knifedogs.com/showthread.php?24556-Rc-Hardness-Testers-VERY-AFFORDABLE
 
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I've done three blades before with no problem. The blades were about one inch apart, sitting upright on a slotted firebrick. I have no idea what happened to the one blade. The blade went into the trash and now resides in the county landfill. Yes, that's the source for the hardness testers. I think he has one set left. Thanks for the replies.
 
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