W2 Question

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I have seen a lot of data about austenitizing W2 @ between 1425˚ -1475˚f. When I austenitize coupons in that range I'm getting HRC numbers in the 30's to the 50's. I have done a salt test in my oven and my actual temps seem to be 55˚f lower than indicated. I have found that, in my oven, I am getting 67hrc when I austenitize @1560˚f (1615˚f indicated). I like the 67hrc but this concerns me because the temps are quite a bit higher than the common data. I know W2 has some vanadium in it that will fight grain growth but is 1560˚f just too high, or am I ok?
 
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Break the coupons and check the grain?

Maybe the 1560F reading is also not correct? Do you have a secondary thermocouple to check?
 

Stuart Davenport Knives

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Marc, is this NJSB W2 that has not been forged? From what I remember about using that stuff, and the 52100, you had to either forge it first or use a very very high normalizing heat. The spheroidizing from that mill is very coarse.
 
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Prior condition needs to be fine spheroidite or fine pearlite, some of the W2 out there is coarse spheroidite which will require higher temperatures and longer soaking.

Hoss
 
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Thank you, gentlemen.

Ok. This is NJSB W2 that has NOT been forged. So, should I soak @ 1900˚f for 10 min to break that speroidizing up, then cycle at 1750˚, 1550˚ and austenitize around 1450˚?
 
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Normalize 1600 for 15 minutes, air cool

Anneal 1400 for 30 minutes furnace cool at a rate of 600 per hour to under 1000 air cool

Austenitize 1450 for 10 minutes, parks 50 oil quench

Larrin might have a slightly different recommendation, but this should work.

Hoss
 
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You have your answer but I found these in my notes so maybe it can help others in the future. The is supplied word doc from njsb

W2 aldo njsb

normalize

(1st cycle)
1,650°F / 898°C (10-15 min)

(2nd cycle)
1,500°F / 815°C (10-15 min)

(3rd cycle)

1,350°F / 732°C (10-15min)

quench - park 50


1,450 to 1,475°F / 801°C ---> 10 min

Do not put blades in oven when cold, insert at or just below austenizing temperature-

temper - 350°F / 177°C 2hrs @ 2x ----> 63/64 rc

———————


**Do not put blades in oven when cold, insert at or just below austenizing temperature--
 
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Note they don’t mention the Anneal step which I think is important and has already been pointed out
 

Stuart Davenport Knives

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I also would like to point out something that I have not tried myself, but I was told this by a very very well known and respected maker who doesn't frequent this site much these days, but he and another maker were troubleshooting why the W2 wouldn't harden properly, and they already knew the spheroidizing issues from NJSB.....(this was several years ago)

The 1650°F normalizing heat was not high enough to get the steel to harden properly. They tried 1900°F and then it all clicked together. Forging guys aren't noticing the spheroidizing issue, because they're heating the steel well above 1650°F. I haven't used W2 in quite a long time, but if MG said it, I believe him.
 

Stacy E. Apelt - Bladesmith

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I use 1800°F as the first normalization step in most W2 and 52100 steels. If it isn't spheroidized, it won't do any noticeable harm. If it is sherardized, it will correct it.
 
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Thanks guys. I ran some 1/8" thick coupons yesterday using Hoss's recommendation. Results before tempering were in the 63-66 HRC range.

I am still curious though about my original post. Although achieving 67HRC, is there anything bad happening in the steel at 1560˚f like excessive grain growth?
 
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Thanks guys. I ran some 1/8" thick coupons yesterday using Hoss's recommendation. Results before tempering were in the 63-66 HRC range.

I am still curious though about my original post. Although achieving 67HRC, is there anything bad happening in the steel at 1560˚f like excessive grain growth?
Plate martensite which will cause a steep drop in toughness.

Hoss
 

Stuart Davenport Knives

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Plate martensite is not good, but I don't think that a steel like W2 with 0.2% vanadium will have grain growth even well above 1560°F. I would think the plate martensite would be the only issue.
 

Stacy E. Apelt - Bladesmith

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This thread brings up something that I often try to explain to new makers. High hardness is not the target. A balanced blend of hardness and toughness is the target.

Glass is much harder than steel, but we don't usually make knives from it.
Wood is much tougher than steel, but we usually don't make knives from it.

What we want is steel that has a chemical composition allowing the atoms to be arranged in a desired structure by a HT which allows moderately high hardness and moderately high toughness. I would far rather have a knife at Rc59-61 that was tough than a Rc65-67 blade that chipped or shattered every time it cut something.
 
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