Help. Quench after Tempering?

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paintballnsk

Joined
Apr 18, 2016
Messages
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Hello,

I've only made like 3-4 blades, however none of them have ever taken a warp. This one was straight after the quench, but took a huge bend after tempering at about 425-450. So I had to re-quench it.

I think it's because I just let it cool over night and it slowly warped as it cooled down. Should I quench after tempering to make sure it locks in? I know there's probably not a lot of clear answers on this one, but has anyone else seen a similar behavior? I was going for a differential quench as well the first time, so I only heated the edge to critical. This time I just did the whole blade. Could that be the issue as well? Maybe I didn't dunk it fast enough, so even though it looked straight after quench, the bend formed as it heat treated?

Thanks,
Nick
 
There is a clear answer. Don't quench after tempering. If you do, you just have quenched steel.

Whenever you heat steel above the critical point "around a cherry red color" you are austinizing the steel, changing its form. This "resets" any heat treating completely.
 
You should temper soon after quenching. This relieves the stress inside the steel. Some steels will even crack if you don't temper soon after quenching.

Was your blade laying flat on its side while it cooled down? This could cause uneven cooling, and could have contributed to your warp.
 
If you are saying you quenched from your tempering temperature of 400-450. That is perfectly fine and actually may add resistance to cold embrittlement. I do this with all of my blades. It will not cause warp.

But, letting it slowly cool won't hurt anything either. Odds are when you checked it for straightness post hardening it hadn't completely transformed yet and was going to warp no matter what.

Aebl has done this to me on numerous occasions. Not knowing any details about your steel or process makes it difficult answer definitively.
 
Warp can be due to any reason in the Universe. You can minimize it by getting your primary factors down, but sometimes it just happens. The temper probably doesn't have anything to do with it though, and like Ben said you can cool it however you want from the temper.

You can take your blade (after being tempered already), and clamp it so your warp bends the other way, then throw it back in the temper. This is one of the easier ways to fix warps post-HT.
 
Thanks.

I re-quenced and made sure I dunked it into the oil a little faster and kept careful attention to the color as I was heating. I always check with a magnet while I'm bringing it up to critical. I should have mentioned I'm using 1095.

I then tempered for 60 minutes and quenched from the tempering heat and it stayed straight.

When it warped, it was straight after the critical quench. I let it cool enough to sand the scale off. Then I left it in the oven over night so it slow cooled from 425 and picked up the warp. There was probably a 5 minute gap between quenching and tempering. I'm guessing I just didn't get an even heat on the initial quench.
 
Also, I'm checking hardness with Grizzly HRC files, and I gotta say, they suck. Don't even bother, or at least figure out how to use them because I haven't. It's straw colored and the 65HRC doesn't bite into it unless I press into it. But you can scratch anything with the 45 if you press hard enough, so I don't really get it.
 
paintballnsk said:
Also, I'm checking hardness with Grizzly HRC files, and I gotta say, they suck. Don't even bother, or at least figure out how to use them because I haven't. It's straw colored and the 65HRC doesn't bite into it unless I press into it. But you can scratch anything with the 45 if you press hard enough, so I don't really get it.
Click to expand...

There is a layer of decarb on the blade that you need to grind off, then you will see the hard steel
 
This is after I've removed the scale. Or are you saying even the layer of straw color is enough to fool the files?
 
To eliminate confusion, the term for what you do after tempering is "rapid cooling". You either dunk the blade in a tub of water ... of do what most folks do and stick it under a running tap or hose. The rapid cool to ambient is not going to warp the blade. As said by the others, warp can come from many things. Most makers learn how to minimize it in their HT program, and how to correct it during temper.
 
paintballnsk said:
This is after I've removed the scale. Or are you saying even the layer of straw color is enough to fool the files?
Click to expand...

Scale and decarb are different. You can remove the scale by soaking in vinegar but you will have to grind the decarb off. One of the most asked things I see here is people thinking their blade didnt get hard but they just needed to grind the decarb away
 
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