Aldo 1/8 Thick W2 Not Hardening

Shaw Blades

Shaw Blades

Joined
May 18, 2009
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Guys,

I've re-done heat treat 3 times on 3 knives and I'm getting an as quenched hardness of 40-42 RC. I use a Paragon kiln, Parks 50, have a hardness tester, the whole shebang.....consistently getting around 40 rockwell out of the quench. Looks like it was ordered May 2014.

Anyone else have this problem? I know there was a bad batch awhile back but I thought this had worked its way through the inventory.

REALLY appreciate any feedback. Thx
 
I got a few bars 4-5 weeks ago and the one i tested worked just fine. Shoot Aldo a message, they are great about helping customers.
 
Shaw Blades said:
Guys,

I've re-done heat treat 3 times on 3 knives and I'm getting an as quenched hardness of 40-42 RC. I use a Paragon kiln, Parks 50, have a hardness tester, the whole shebang.....consistently getting around 40 rockwell out of the quench. Looks like it was ordered May 2014.

Anyone else have this problem? I know there was a bad batch awhile back but I thought this had worked its way through the inventory.

REALLY appreciate any feedback. Thx
Click to expand...

How hot are you getting it, and how long are you soaking? And, how quickly are you getting it from the oven to the quench? And how fine is your grain? These things all matter, especially with water hardening steels.

Also, where are you testing for hardness? I find I usually have to test near the edge, because W2 won't harden all the way to the middle of thick parts like tangs.
 
1475, 20 minute soak, checking on handle area, around middle of it. Very quickly into the parks 50 like less than 1 second. I'll break a piece later tonight.
 
Shaw Blades said:
1475, 20 minute soak, checking on handle area, around middle of it. Very quickly into the parks 50 like less than 1 second. I'll break a piece later tonight.
Click to expand...

Yeah, try testing for hardness near the edge. 40 rc is about what I get testing in the middle....
 
Makes sense to me
with the edge usually being thinner. so it would cool faster then the thicker area during quench
Plus you'd think 1/8 (no exp here) would cool very quickly coming out of the oven. Perhaps a slightly higher heat in the oven right before the quench to compensate for the cool down from oven to quench.
Lol at least in my crazy mind it makes sense
 
It should harden all the way through for knives thickness.
I would try a normalization at at least 1600 °F, then your usual procedure. It could be a case of heavy spheroidization you got there.
 
I tested the edge, it tests the same. I thought such a bin cross section (1/8) would harden deeper as well.

That's a good idea about the 1600 normalize. This is the fist time I've used w2 not trying to get a hamon, I didn't grind any bevel, just profiled the blade, normalized a couple of time then best treated on the 3rd cycle. Total stock removal blades.
 
Stezzan has the words taken right from my mouth. I am of the opinion that ALL of the carbon steels that Aldo carries should be normalized due to their spheroidized condition. Some of us remember the 52100 issue, and that was squared away by normalizing. That particular 52100 was "heavily" coarse spheoridized. You'll notice at the bottom of Aldo's ordering screens, it says 98% or 95% spheroidized, on just about all the carbon steels. Because I have no way of knowing if a certain steel is coarse spheroidized or fine spheroidized.......I cannot recommend enough that a normalizing routine is done on these steels. That way you KNOW what structure you are dealing with, and how to handle it.

A fine spheroidized steel can harden quite readily, but a coarse spheroidized steel really needs a normalizing (or possibly a very long soak at austenitizing temp). I'm not sure if the problem you are having is the spheroidized condition, or something else altogether (that funky batch he had a couple years ago). But normalizing at 1600F-1650F would be my first step in narrowing the problem down. Just remember to do a few cycles at a lower temp to help refine the aus grain after the normalizing heat.

Going from the forge/kiln to the quench tank should not be a super duper rush....even on shallow hardening steels that require a fast quench. Keep in mind that the "less than one second" does not mean you have less than one second to go from the austenitizing temp of 1475F down to under 900F in less than one second. It means the OIL has less than one second get it under 900F. As long as the steel gets into the oil above recalescence (spelling?), you're good to go. The carbon is still in solution.
 
20 min (at temp) is a long soak, and capable of causing some decarb.
Try removing some surface material prior to checking hardness.

BTW...1/8" W2 should harden all the way through.
 
Russ Andrews said:
20 min (at temp) is a long soak, and capable of causing some decarb.
Try removing some surface material prior to checking hardness.

BTW...1/8" W2 should harden all the way through.
Click to expand...
Like Russ said, not only long, but 20 minutes is too long a soak. There could be other problems lurking though, I don't know?
 
Not necessarily. Blades will reach temp more slowly in a kiln, than in a forge...usually, but once at temp
soak time would be the same.
You'd need to experiment with soak times and your equipment, but 5-6 min at temp will be a place to start.
 
I have done about 25 knives from Aldo's 1/8 W2, and use the same thermal cycling as discussed in the 52100 thread linked above. I get Rc68 out of quench when austentized at 1460f. Up or down 10f decreases consistency, and 20f sees a drop in initial hardness. 30f (1490f, or 1430f) and I see low 60s for initial hardness. When heat treated at 1460f, The grain is super fine, and wear resistance is pretty much equal to the 52100. I learned the importance of normalizing, thermal cycling, and using 10f variations in austentizing temp to account for variations in equipment from shop to shop. IIRC, Don uses 1450f in his shop with his steel. Learn your equipment.These are my go to steels now, using 52100 for full hardness blades, and W2 for differential hardening.
 
Kyle & I just finished 4 fillet knives using W2 at .075" thickness (ground bevels after HT). Normalized 3 times after forging. 5-6 minutes soak at 1460 after the oven recovered temp. Quenched in Parks 50. Hardness as quench 66-68 Rc. Two, one hour tempers T 450f produced 61-62 Rc. They work very well.



 
Willie71 said:
I have done about 25 knives from Aldo's 1/8 W2, and use the same thermal cycling as discussed in the 52100 thread linked above. I get Rc68 out of quench when austentized at 1460f. Up or down 10f decreases consistency, and 20f sees a drop in initial hardness. 30f (1490f, or 1430f) and I see low 60s for initial hardness. When heat treated at 1460f, The grain is super fine, and wear resistance is pretty much equal to the 52100. I learned the importance of normalizing, thermal cycling, and using 10f variations in austentizing temp to account for variations in equipment from shop to shop. IIRC, Don uses 1450f in his shop with his steel. Learn your equipment.These are my go to steels now, using 52100 for full hardness blades, and W2 for differential hardening.
Click to expand...
I think it was after that thread I started using 1460. :)
 
Just a thought, are you putting the blades into a cold kiln and heating, or is the kiln taken to temperature and then the blades inserted? Eighth inch stock is easy to overheat if its done this way.

Fred
 
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