W2

Don Hanson III said:
Phillip, specs below thanks to Russ Andrews.

C .95,
Mn .22,
V .19,
Cr .15,
Si .23,
Mo .013,
Ni .08,
Cu .14
Click to expand...

Thanks, Don. I will use that analysis to point out a bit more of what I was saying.

First, there is enough carbon to have just about .10% surplus after tying up the rest in the eutectoid. The same as 1095 in carbon content. The extra .10% of carbon is just enough to combine with the small amount of carbide formers, with no excess. What you would call a balanced alloying. Don's HT is designed to put just the right amount of carbon into solution to make the eutectoid and leave the rest as small carbides.

The big thing that separates this W2 from most all other W2 is the second number. The manganese is LOW. This makes the steel very shallow hardening. It requires a quick quench, and will take a very active hamon. Shallow hardening is a term that describes how a 1" round bar will harden. Knife blades are different, and will normally harden all the way through. In very shallow hardening steels, a knife blade may harden through at the edge, and only partially above it. This is called an auto-hamon, and Don is the champ of that technique. With exact temperature control and skill, a very active hamon can be created with no clay at all.

The vanadium is there in a very small amount to facilitate fine grain and slightly deepen the quenchability. This helps the edge harden better. The tiny amount of chromium adds a little more toughness and edge wear. It isn't enough to affect getting a very fine edge.

Silicon is a requirement in making steel. There will be a certain amount of silicon in all steel.

The traces of molybdenum, nickel, and copper are the ghosts of previous steels used in the melt at the mill. They are low enough to be of no issue, and their presence in this steel have no adverse effects.

So, what you have is 1095 with very low manganese and just a little grain refining vanadium, plus a little toughening chromium ... If someone was trying to market this as a special steel, they would probably call it 95CrV. We all just call it "Don's W2".
 
Comments on composition ..... W1 and W2 have a very wide range of carbon content though melting from a mill might be narrower. That means you should find what a mill melts to and stick with that mill .Also note that Ni and Cu are listed .They are not added with intent but appear because we use steel that has been reprocessed from scrap ! They are 'trace elements ' and 'tramp elements ' if unwanted metals. In either case if they are in high amounts they may have a noticable effect on HT or properties.
As Don says --little things mean alot !
 
What are some of the common failures with W2 blades? What changes with high carbon content W2 in relation to heat treat?

This thread is priceless to me, thank you all.
 
The most common failures in W2 blades are cracking during quench, and not getting sufficiently hard.

The higher carbon will make HT trickier. It means more carbon for excess carbides ... which isn't what we want in W2 blades.

It will lower the austenitization temperature to the very bottom of the range. This means quench time drops to an unrealistic fast speed. water quench becomes the only option for getting any martensite. Blacksmiths probably don't care, but to a bladesmith, this is a big issue.
 
Willie71 said:
I asked Kevin Cashen why W2 was better for a hamon than 1095, with similar carbon and manganese numbers. He told me the effect of the vanadium in the steel created the extra activity. Aldo's W2 is quite similar to Don's. It was smelted based on an analysis of Don's stock iirc. Don does have that W2 with the alloy banding though. I regularily get Rc67/68 with this steel. Great stuff. Great edge stability and edge retention.
Click to expand...


So where does Don Hanson get his W2?
 
Ive have just completed my first knife using W2 and I have a couple of questions if anyone who is experienced with this steel would be able to share their knowledge.

1) why does the hamon differ from where the clay is set out? (sometimes?) I have quenched a large blade (2 inches tall) and set the clay approx 1/3 from the top. When you look at the hamon its quite close to the edge. Is it possible a vapour blanket is caught by the clay? or is can residual heat in the spine move the hamon? -(ive got a couple of pictures if these are helpful)

2) If you do see a visible hamon line, what can you assume about the hardness of the steel on the edge. eg. can you assume it is at least X hardness? or has it to do with the relative hardness between spine and edge? (eg. could you have a hamon and only get to RC 55 or something upon hardnening, or will the edge always be at least rc 65 or 60+?)

thanks in advance :D
 
ndp_2010 said:
1) why does the hamon differ from where the clay is set out? (sometimes?) I have quenched a large blade (2 inches tall) and set the clay approx 1/3 from the top. When you look at the hamon its quite close to the edge.

2) If you do see a visible hamon line, what can you assume about the hardness of the steel on the edge. eg. can you assume it is at least X hardness?

thanks in advance :D
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1) The transformation to martensite is related to the speed of the cooling of the steel; the clay adds insulative factor, but also the steel thickness and the speed of the quenchant influence what part of the steel cools fast enough to produce martensite. I.E.: you could quench into oil a full high bevel with no clay and get auto hamon. or you can use a thick layer of clay up to 1/2 of the bevel and get no martensite at all.

2) Not all the martensite is equal under the hamon; if you underaustenitize the blade you can get martensite, but not as hard as if you put the correct amount of carbon in solution. Or you can get a mix of perlite in the martensite if the quench is not fast enough, lowering the overall hardness....OR you can overaustenitize and get martensite + RA with the same outcome.
 
Stezann explained it pretty well in technical terms.

What happens in simple terms is that the heat is retained longer under the clay, and in the thicker steel. This heat "bleeds" down the blade toward the edge as the quench happens, and during the time when the blade is pulled out. This is part of why the hamon has a bit of wiggle to it, because many things affect how far the heat bleeds. The point where the heat is sufficient to prevent the martensite from forming, or to temper it back severely, is the hamon. You have to experiment a bit with your steel and determine how high and how thick the clay should be to get the desired hamon. It rarely is exactly where the clay is ... usually being about 1/4" from the clay edge. The biggest novice mistake is putting the clay on thick. This will almost guarantee the hamon going down to the edge on a very shallow hardening steel like W2.

As Stezann pointed out, the structures in the hamon are varied. The old name was Troosite, which was a term for the mixture of pearlite and martensite in the hamon. Today, no one but me seems to use that term ... guess that shows how old I am :)
 
Thankyou for the explanation. I will try less clay and position it higher on the blade next time I do a big knife. The one I have done was quite thick at the spine and tall, so I guess lots of retained heat.
 
I know this thread is about W2, but what about W1? I have a very well priced source of w2 round stock near me. Would the heat treat be similar?

would you expect to need a soak and 3 phase normalization? I'm going to experiment, but I want to find a starting point.

couple of data points I got

C: .94%
Mn: .4%
Cu: .16%
 
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C: .94%
Mn: .4%
Cu: .16%

The bulk of W1 available from places like Fastenal is around that analysis. I call it very clean 1095. The HT is the same as 1095 or W2.

To reiterate my earlier caveat - you have to know the makeup of the W1/W2 you buy, because it can vary greatly.
 
I love W1. I have been getting it in round bar and forging it down. It forges very easily, and can get a nice hamon. I have been heat treating it the same as my W2 as well. I don't remember the exact composition of my steel, but it has 1% C.
 
Also be very careful when you order "W2" from a supplier. I got a quote from a large supplier that was going to provide me with W2 in 1.5" square bars at a reasonable price. That was until I asked for an analysis. Then they told me they were intending to sub W1 without telling me. I would not have been happy.

On another note. I just did a batch of heat treating several W2 blades. I have tried the lower temps before and for some reason they just don't work for me and my set-up. I tried the 1450F once again using Dons W2. I had 5 clayed blades. I have learned the clay needs to be very light and basically just heavily painted the clay onto the blades. I Tried after a 10 minute soak and the Hamon was pushed way down on the blade like within 1/8 inch of edge. These were very thin blades too. So I upped the temp to 1475f and tried the 3 remaining at that temp. Came out great. Even the blades I had to redo. Just goes to show it can be different for each set-up. Wonder if elevation has something to do with it?
 
Great Masters like Kevin Cashen don't want to give "recepits", and one of the good reasons is we all work with different setups. Let alone differences in the steel batch, my readings of 1475 °F may be different to the absolute temperature of my blade, and other's TC may read also a bit differently in the same situation. Just relying on other people's number may be misleading. We need to find what works in our environment and take notes. Most of us don't work in the tight specs of a laboratory, precision and accuracy are the ones we can afford.
Grain size is directly proportional to the hardenability, so higher temperatures lead to higher hamon and vice versa
 
You are right, unlike cook book recipes, in ht we implicitly state ht temp in isothermal. Users have to tune them for their environment.

Please elaborate on why(s): Grain size is directly proportional to the hardenability? Also applicable to statement such as - W2 is more difficult to harden with each additional grain refinement thermal (beyond 2 cycles). Most obvious/well-stated reasons are being: higher recales intensity; more gb precip due to more gb interface volume; lower equillibrium aust temperature. On one hand, we want as fine grain as possible, otoh don't get too fine or you won't able to properly harden it <= woah, how's one determine the cross-over line? or is this line applicable to my(I meant, you - a particular ht) setting?

stezann said:
Great Masters like Kevin Cashen don't want to give "recepits", and one of the good reasons is we all work with different setups. Let alone differences in the steel batch, my readings of 1475 °F may be different to the absolute temperature of my blade, and other's TC may read also a bit differently in the same situation. Just relying on other people's number may be misleading. We need to find what works in our environment and take notes. Most of us don't work in the tight specs of a laboratory, precision and accuracy are the ones we can afford.
Grain size is directly proportional to the hardenability, so higher temperatures lead to higher hamon and vice versa
Click to expand...
 
stezann said:
Great Masters like Kevin Cashen don't want to give "recepits", and one of the good reasons is we all work with different setups. Let alone differences in the steel batch, my readings of 1475 °F may be different to the absolute temperature of my blade, and other's TC may read also a bit differently in the same situation. Just relying on other people's number may be misleading. We need to find what works in our environment and take notes. Most of us don't work in the tight specs of a laboratory, precision and accuracy are the ones we can afford.
Grain size is directly proportional to the hardenability, so higher temperatures lead to higher hamon and vice versa
Click to expand...

Spot on. This is how I came to use 1460f with Aldo's W2 in my shop. I tested a bunch of coupons, and that is what works for me. Stewart mentioned different outcomes with tempering from Don. I tested my tempering temps, and whether my oven is correct or not, I got the same Rc#'s as Don does with his tempering. If I switch to a different oven, I will test again.

Another thing to consider is the effect of grain refinement on hardenability. The finer the grain for a given steel, the lower the hardenability. Kevin told me he tested 1095 that was so refined it could not harden. Normalize, and it would harden again. Edit: I missed that you commented on this. Whoops.

With W2, the clay shouldn't be more than 1/8" thick. I'll go a bit thicker with 1095, and 10f hotter austentizing. Slight difference make a big difference. Journal your results and keep doing what works.
 
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