W2 heat treating results

Status
Not open for further replies.
Robert Erickson

Robert Erickson

Knifemaker / Craftsman / Service Provider
Joined
Feb 2, 2014
Messages
2,864
Hi guys,
There has been some recent discussion regarding the W2 that's currently available and it's inability to harden consistently throughout the steel. I have some of it and so I wanted to try some different protocols to see if I could produce more consistent results. I don't pretend to be an expert by any stretch of the imagination but I thought I would post my results.
My equipment consists of and Evenheat KF 22.5" oven with TAP controller and a Grizzly hardness tester that is calibrated.
All coupons were approx 3" long by 3/4" wide and were coated with ATP 641 antiscale compound before normalizing and thermal cycling.
The first 3 coupons were all normalized at 1650 X 15 min then thermal cycled at 1550 X 15 min then 1350 X 15 min with cool to black in between heatings.
Three Aus temps were used for these coupons: 1450, 1470 and 1480 X 15 min, all quenched in Parks 50. Decarb was ground off all coupons with my surface grinder attachment before hardness testing.
The coupons were then RC tested in 3 places: at both ends and in the middle. I didn't temper any of the first 4 coupons as they were so inconsistent.
As quenched hardness results:
1450: 42, 51, 51
1470: 50, 61, 48
1480: 52, 67, 45
The next coupon was normalized at 1800 X 20 min, then 1550 X 15 min then 1350 X 15 min
then Aus at 1480 X 15 min.
1480: 64, 48, 60
The last coupon was normalized at 2000 X 10 min, then 1550 X 15 min then 1350 X 15 min then Aus at 1480 X 15 min. I chose 2000 because that is approx forging temp.
Results: 64, 65, 64
After Temper X 2 at 350: 62, 63, 63
The last coupon was broken and the grain examined:

80E6L5L.jpg


These results are with my particular equipment and are a small sample size so it's certainly not a scientific grade experiment but it seems to indicate that this particular batch needs to either be forged or normalized at near forging temps to get it to fully and consistently harden. It certainly isn't Don's W2 but should make a good blade with nice hamon. I've certainly learned that I need to be testing the steel I get more often.
 
Last edited:
That was an awesome experiment, thanks for sharing!

Any metallurgy experts out there can explain why normalizing at 1650F x15 minutes and 1800F x20 minutes didn't work well but 2000F x10 minutes worked tho?
 
I'd be curious as well to what our resident metallurgy gurus think.
My thought was that it needed that heat to get all the carbon evenly distributed but I'm just guessing.
 
Not sure why but the scatter is wider than I’ve ever seen on the early coupons. All testing is good for learning.

Hoss
 
It could be that you increased the grain size for higher hardenability.
 
Thanks Larrin, that's interesting. Then the thermal cycling reduces the grain down again? I know it might be hard to tell from the picture I posted but does the grain look OK?
 
That’s disappointing numbers honestly. That’s good work you did though. Good W2 should be easily hitting 66+rc with those aust temps.. I usually use 1460° and parks but I don’t have any of the new batch w2
 
I know of one other maker who was brought in to troubleshoot the recent W2 from Aldo and had very similar results. They couldn’t get decent hardness numbers unless it was normalized at 2000f. I know of another maker who gets great results from it, but he is forging it, and thus not noticing the problem.

Agreed that even the post quench hardness (even after the 2000f normalizing) is lower than it could be. I would be curious as what the hardness would be if the austenitizing temp was bumped up to 1500f (or slightly higher).

As to why the extremely high normalizing heat, maybe the stuff is extremely spheroidized. Like SUPER spheroidized. And extremely shallow hardening as received.

I wrote off ordering any of the latest W2 after hearing about this very issue after it came in and these makers, who are extremely proficient at their craft (you know the names), were having this exact same problem. Which was a let down because I was excited about using the 0.09” stock. Oh well.
 
Thanks for running these tests, i've got like 50ft of the new thinner W2 from Aldo, but haven't messed around with it yet. This has made it so i will most definitely be running some tests on my own setup before making anything out of it. Bit disconcerting that arguably one of the best knife steel suppliers is running into issues like this still. I mean it was a good half a decade+ ago that they had that entire batch of W2 be bad, figured they woulda ironed out those type of kinks by now and with how much they buy now, be running tests of their own to confirm its good stuff.
 
I'll try a few more combinations and see if the numbers come up any better.
 
I have purchased two batches of W2 from Aldo within the last year....results are consistent with both. I am using an Evenheat w/ Rampmaster and a Grizzly tester.

Normalization: 1600 x 20 min, 1475, 1450, 1425 each x 15min all air cool
Austenize: 1460 12-15 min, quench Parks 50 getting 66-67
Temper: 360 /2hrs x 2 sessions, getting 62-64

My grain structure is similar to the finest in your photo, but it is consistent across the entire coupon.
 
Last edited:
That's great Carter! I'm curious if you're taking measurements in different locations? Before altering the protocol I was getting some spot reading that were OK but wide variations over the course of the blade.
 
I am on the coupons and on both sides....I start getting good and consistent results with the metal sanded up to approx 200 grit. Also have tested along the length of harden full knife blades....results are same. I have found that a good finish on the steel is most important.
 
Carterwhopkins said:
I am on the coupons and on both sides....I start getting good and consistent results with the metal sanded up to approx 200 grit. Also have tested along the length of harden full knife blades....results are same. I have found that a good finish on the steel is most important.
Click to expand...

Iirc, your steel hardened without the 2000f normalize, and hardens at 1460f. You likely have the previous batch.
 
I have been concerned with all the talk regarding this steel, but all my W2 is performing similar to 52100 from NJSB, except I take the W2 about 1 point higher in hardness. My heat treatment is the same basic recipe with slightly different temps....and sometimes a canola quench.
 
Carterwhopkins said:
I have been concerned with all the talk regarding this steel, but all my W2 is performing similar to 52100 from NJSB, except I take the W2 about 1 point higher in hardness. My heat treatment is the same basic recipe with slightly different temps....and sometimes a canola quench.
Click to expand...

You've certainly done your due diligence Carter. If you buy additional W2 I'd be curious as to your results.

drew1972 said:
I've been having the same problem with a batch of 1095 I got about 6 months ago.
Click to expand...

With non hardening or inconsistent hardening? Have you tried higher temp normalization?
 
Robert Erickson said:
You've certainly done your due diligence Carter. If you buy additional W2 I'd be curious as to your results.



With non hardening or inconsistent hardening? Have you tried higher temp
normalization?
Click to expand...

With inconsistent hardening. I will definately try higher normalization Temps now that I've read this.
 
Status
Not open for further replies.
Back
Top