Two Large 52100 Blades Cracked Down Spine

Thanks Bill for posting on this. It always is good to hear from a master smith who has put in the time doing the testing and sharing what they found.

Very interesting.
 
Just wanted to say thank you to Bill Burke for your input. You guys are ten billion times more knowledgeable than myself when it comes to heat treating. 52100 has more recommended heat treats than any steel out there, it seems. I guess that comes from various methods and opinions on how to handle the carbides, their size and distribution. I have never tried the comparison myself, has anyone compared two knives side by side, identical, with one receiving the triple quench method, as Mr Burke and Mr Fowler use in their shop, or the single quench method as recommended by others? Would anyone be able to differentiate between the two in normal use? I'm all for making the best blade that I possible can.
 
Those are great results, Bill. I still think you are doing things you don't need to do(namely, the 24hr wait times)... but we can discuss that at the next Blade Show over a beer. I at least owe you that for the game of 20 questions.

Stu, even though Bill and Ed are doing a triple quench, I believe Ed uses a torch on the edge where Bill is calling out actual temperatures which leads me to believe he uses a kiln and fully quenches.
 
Rick Marchand said:
Those are great results, Bill. I still think you are doing things you don't need to do(namely, the 24hr wait times)... but we can discuss that at the next Blade Show over a beer. I at least owe you that for the game of 20 questions.

Stu, even though Bill and Ed are doing a triple quench, I believe Ed uses a torch on the edge where Bill is calling out actual temperatures which leads me to believe he uses a kiln and fully quenches.
Click to expand...

hey Rick no problems.

for the most part I still use a torch when I harden knives. For testing purposes I use salt or an oven so I have specific temps that are exactly repeatable. I also repeat these tests using a torch to see if there is a difference between torch heating and oven salt heating.

I test the knives by slicing hemp rope, chopping into dry elk horn and wood 2x4s. I test for toughness by flexing the edge over a polished butchers steel and whacking the spine and sides against my anvil horn and then I clamp the blade in a vise and bend it 90 degrees. thicker hunting knives will normally bend 90 and then return to within ~thirty degrees of straight. thin kitchen knives normally return to straight or <10 degrees of straight depending on how wide the blade is and how much of it is hardened.
 
Here's my last update. I triple quenched another blade this weekend, same regimen as before except it was stock removal. Had no cracking issues. I'll try to forge the 52100 at night next time so I can see the colors better.

Thanks for everyone's input.
 
Hi Bill, tought that you need time to dissolve the product of a real speroidal anneal in order to get back carbon evenly into solution... unless you prefer an uneven martensite matrix with lot of big carbides, that may help in a skinner knife.
But i realize i misunderstood your procedure, which implies 3 quenches...probably then you dissolve your carbides "step by step" and you are happy with your results, so am i.
I'll be glad to see the pictures, i always love steel micrography, and i like to see your knives, by the way, which i consider among the best :thumbup:

cheers

Stefano
 
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