False edges, clip points, and the dreaded "ping"

N

Ninja Blacksmith

Joined
Aug 26, 2012
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136
I have a question, before I waste another ever-so-precious piece of W2. I have begun to notice a pattern among my failed differentially hardened blades - the ones that fail are the ones that have false edges and clip points similar to bowies. By adding a false edge of any sort just beg for cracks during the quench, or is there some way to get around the problem - if it is a problem? I have experience with heat treating short Japanese style blades from both W1 and 2, but anything with Americanized features seems to be an entirely different beast for me. Is there a different way I should approach adding clay to the flats of bowie-type blanks?
 
Need much more info on your process to give any advice.

Clips should not cause failures unless you are leaving stress risers. If all else fails grind them in after HT.
 
Also, what are you quenching in? Sounds like water... I've been using Parks 50 and nary a ping since. Are you normalizing and such first?
 
For quenching, I haven't had any issues (except one a couple years ago) with brine quenching after the blade spends a few minutes just a bit above non-magnetic - UNLESS it's a bowie-ish knife, then crap hits the fan fast as soon as it's submerged. From examining the failed bowies, the ricasso and choil appear just fine, and the cracks seem to concentrate between where the false edge begins and the tip. These cracks aren't on the false edge, but along the cutting edge. The false edges have been ground at a shallower angle than most others I've seen, are steeper grinds known to handle it better? As for claying, I apply it much the same way I would on something like a tanto, except for leaving a little of the clip or false edge uncoated. Could this be what's causing the pings?

Salem: I didn't bother normalizing since this one was done via stock removal. Also, I've been looking for this parks 50 stuff for nearly a year. Is there a supplier you can recommend?
 
I've made hundreds of blades from W2 & W1, most have had false edge, or double edge. Have never had one crack. Park's 50 is the stuff! Someone will come along with the source, I don't remember the new place people or ordering from now days.
 
Kelly Cupples has parks 50 (octihunter at charter dot net)

Brine is a ping factory. Some have success but I have not been able to do it reliably. Parks 50 is the way to go. It taint cheap but worth every blade you will save.

Also always normalize, you have no idea how the steel was treated at the factory.. The worst that will happen is you have better grain refinement.
 
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Thanks all; I will certainly look into the posted sources for Parks 50. Until I manage to acquire some, I'll just stick to tantos and the occasional wakizashi.
 
Before I had my commercial oil, I did 3 seconds in brine, interrupt and into heated canola oil. From what I have read, its the second half of the transformation that causes the excess stress, which is where the commercial oils cool slower than brine.
 
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