Tink! Well crap....

A.McPherson

A.McPherson

Knifemaker / Craftsman / Service Provider
Joined
Jan 27, 2012
Messages
2,934
Well, I knew it would happen sooner or later, but here it is. First failure in the quench!

Trying for a hamon, used brine instead of oil aaand snap! Broken blade! Bummer of it all is the hamon looks like it might have actually been a good one! Sigh!

I knew better but I didn't want to wait till I bought some oil. Dummy! Don't rush!
 
Next... try water for 2 seconds, then to oil.

I totally just made that up.

Seriously though... I do something like that for my hammers. Usually 1050/1070. If I fully brine quench, I risk cracking. Too little and they auto-temper. A 4 second quench in brine, then to the oil for the remainder works well.
 
Thanks Frank, I'll post pictures later. I'm thinking of finishing it out a bit, just to see how good it COULD have been. Maybe I'll salvage enough to make something small out of it...


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Thanks Rick, I was wondering if something like that would work...
I actually did something like that I quenched for a couple seconds then took it out for a second or two and then put it back it. It actually broke on the second dip.
The brine was warm when I quenched, but I wonder if interrupting the quench kind of "broke" the vapor jacket that was there initially...


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Brine is fast because it essentially self-agitates. The water vaporizes and the sodium/calcium chloride explodes, breaking up the jacket. I might be off on the science but this is how I keep it straight in my head. My goal(with water quenched steels) is to drop below the nose fast with the initial brine/water quench, then get it into the slower medium before it reaches Ms, allowing it to slowly play out to Mf. Seems to me that in water, the surface gets to Mf well before the core gets to Ms. At least in larger cross sections like my hammers. I do not have a lot of experience with quenching clay coated blades.
 
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Hmmm interesting.... I do wonder if I had just left it in, if it would have broken. Probably, I have been thinking about the threads I have read on here about brine quenching, and I did some things wrong. It had a rough finish, which can introduce stress risers. And the edge had 90* angles, which can introduce stress risers. Guess where it broke? On the edge, on a particularly deep grind line. Huh! Imagine that!

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Oh ya... that finish is WAY to rough for a stressful quench... any quench, really. Mine get a 220gt finish before the quench. And, I Scotchbrite all the corners.
 
I just tried water quenching a W-2 blade for a hamon and it also cracked. Looks like you would have had a very nice hamon.
 
Yeah, I'm pretty bummed about it Tom, I was really looking forward to having something cool to show you next time! Lol! Oh well!


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I'm still quenching in brine, or really just strong salt water. I guess I'm to cheap to buy a bucket of oil.

For the lest six or seven blades I've ground the bevels after heat treat and I haven't had any breakage during the quench.

Now I just break blades trying to straighten them during tempering.
 
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