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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making.

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  #1  
Old 08-04-2017, 04:09 PM
armandanvil armandanvil is offline
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Poor results with 15n20

Greetings all....
Have been using large band saw blade for knife blades but they don't seem to hold an
edge well, and being hard to sharpen they seem to be hard enough. Have been quenching
in oil at non magnetic/critical temp. and temper at 400-425 F. for one hour. Was once told
to take up to higher temp. before quench. Any ideas?

Thanks
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  #2  
Old 08-04-2017, 05:27 PM
jmccustomknives jmccustomknives is offline
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Have you file tested out of the quench? Does the file skate (not cut into the steel)? Are you sure it's 15n20? Quite often those band saw blade that everyone thinks are 15n20 aren't. It's more common to find them that aren't than are.
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  #3  
Old 08-05-2017, 02:21 AM
Doug Lester Doug Lester is offline
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Take what up to a higher temperature? You may have to go a little higher than non-magnetic to achieve phase change in the steel. 15N20 is basically 1070 with about 1.5% nickel added so it will tolerate going up to around 1600. For that low a carbon steel I think that I would give 375 a try for tempering and see if that improves the edge holding.

Doug


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  #4  
Old 08-06-2017, 08:23 AM
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You mentioned "non-magnetic"....first thought is that you're not hot enough when quenching.... generally critical is 150-200F above "non-magnetic". You also mentioned "oil", but didn't say specifically what the oil is.

Remember that the steel must be AT LEAST critical temp when it hits the oil.... I say that because lately I have had several individuals who've contacted me with similar issues.... and I discovered that their quench tank(s) was 10+ feet away from their heat source when quenching.... very likely they were way under critical by the time they got a blade into the quench.

Also, don't discount the impact of a blade's geometry when it comes to sharpening/cutting..... if the primary/secondary bevels are obtuse, both ease of sharpening, and cutting performance will suffer.

Tempering temps can't be nailed down to a specific temp just based on a steel type. It requires some experimenting for the given steel, with the given grind, and even the specific type of edge geometry applied.


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  #5  
Old 08-06-2017, 05:34 PM
jimmontg jimmontg is offline
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First thing I'd tell you is don't mess with mystery steel and have any great expectations unless it's an old Nicholson Black Diamond file. James said above a lot of bandsaw blades are not made with 15N20 anymore and many never were. You could have some S7 steel there and it doesn't get as hard as one might like a knife to be (yes they made sawmill blades from S7). 8670 is a common one now and there are better alloys being used for saw blades than ever before. Heat it to 1500-1600 degrees or a nice bright orange heat and then quench and see what you get. Temper immediately if it's hard, start around 350 for an hour. S7 at 400 degrees wouldn't hold an edge very well at all if that's what you have. How old is this stuff?

I suggest that if you want 15N20 order it from Alpha Knife Supply or NJSB. It only comes 1/8" at the thickest, but will make an awesome insert on the inside of an ax. It is very shock absorbing and will harden around the file skating hardness range. It is fairly cheap and is forgiving. Best for Damascus.
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  #6  
Old 08-07-2017, 08:35 AM
Kevin R. Cashen Kevin R. Cashen is offline
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Sorry for the topic drift, but this thread revealed something very interesting to me about this forum. The last post of any kind was back on April, and yet within 48 hours of this question being asked multiple answers were quickly posted. I was surprised at the size of a thread that had just started. This tells me that this forum is not dead like some get, but rather there are many people visiting and just waiting to answer questions, as soon as somebody has one. That is a good thing for visitors to know.

As to the initial question, as has been said, these are one of the major pitfalls of using mystery steel, and even those most knowledgeable in heat treating can't fill in the blanks if they don't know what it is.
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  #7  
Old 08-09-2017, 11:25 PM
jimmontg jimmontg is offline
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I am glad to be part of this Forum Mr. Cashen

I have learned much here and there are folks who are happy to impart knowledge to any that ask.

As for 15N20 I am fond of this steel and wished it came a little thicker. It is as forgiving as 1084 in my experience in a forge and as I said above makes a great insert in the center of a forged ax. I have a hand forged ax right now I am almost certain is 15N20 because it doesn't turn black when I dripped some ferric acid on it. There are no markings and a file just skates off the surface. All I am going to do is reshape the outside a bit and re-handle it. Will make a nice Hudson's Bay Ax.


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Old 08-10-2017, 12:13 PM
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Quote:
As for 15N20 I am fond of this steel and wished it came a little thicker.
The sad fact as to why it doesn't is because we, as knifemakers, comprise such a small percentage of steel buyers, that steel producers feel we are irreverent from a sales standpoint. Same thing when the steel industry quietly changed the Mn content standards of 1095..... when I figured out what was going on when many folks couldn't get their 1095 to harden, I called a couple of my contacts within the steel industry to question the change. The answers I got were "Knifemakers are such a small percentage of steel buyers, we really don't care what you want." Not the answer I wanted, but at least it was an honest one.

Thank goodness for people like Aldo Bruno....and a very few others who cater to knifemakers.


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Old 08-10-2017, 03:57 PM
jimmontg jimmontg is offline
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Yes Ed it is good there are some folks that cater to us knife folks. The W2 will be drying up unless Aldo orders 2,000 lbs of it at once as the mill will not make less is what I was told by a Cincinnati Tool Steel rep. If you want L6 tool steel only Aldo and CTS have that in any amounts and I think Aldo is out. CTS has it in 3/8" thick plates and 1/2" sheared to size.

I remember Bob Loveless had ARMCO make him a special run of steel when they still had their custom smelter. I wonder if there are any of those still around.
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Old 08-11-2017, 11:36 AM
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Several years ago, a group of makers here in the NW tried to get a special run of 1084 made.... once we determined the chemistry we wanted, we started searching for a company who would make it for us. We found a few, but at that time none would produce it for us unless we pre-paid for at least 30,000 pounds. Suffice to say that it was simply out of reach financially, even though we had a sizable group.

I've been at this for many years, and at no point in time has it been more difficult to find/acquire "good" steel then now. My advice to anyone who finds a good source, is to buy as much as you possibly can at the time.... it's not ever going to get any cheaper, and it won't go bad on the shelf.

Recently I made a $1,000+ steel buy, and will be making another as soon as I can afford to.


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  #11  
Old 08-11-2017, 12:24 PM
jimmontg jimmontg is offline
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Ed the rep at Cincinnati Tool Steel said 2,000 lb run for W2 and he did say NJSB had ordered from them in the past. I spoke to the Columbia SC branch. So if he wasn't mistaken one could get a group together to score a ton of W2 although I wouldn't want that much or even W2 at all. There are less picky and better steels like O1 with Vanadium in it. I am interested in CruForgeV and would be interested in hearing from someone who has forged it.
Here is a link to CTS if anyone is interested in forging real L6 or S5 which hardens much, much harder than S7. L6 has enough nickel in it to make Damascus with it too. CTS has heat treating instructions for them, although for 7/8 round rod, but it's a good baseline to start if you've never used the steels before. But L6 comes only in thick sizes so forging is pretty much the name of the game.

http://www.cintool.com/index.asp
Not all the branches carry everything in stock either.
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Old 08-11-2017, 04:41 PM
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I've forged and finished a number of knives from CruForge. I was one of those who was asked to "test" it.

I did about a dozen test blades, and about another 1/2 dozen that were sold. It's fairly easy to forge and work hot, the tough part comes after heat treating.....once heat treated it's simply a bear to work with/finish. The only other steel I can compare it to in terms of difficulty in finish is S30V.

I was all set to make it one of my "standard" steels, then when crucible went under, and there were no plans to produce any more of it, I abandoned it....no sense wasting time/effort on a steel that will become extinct.

I've since turned my attention to 80CRV2. I'm still in the testing stages with it, but so far it looks very promising....just hope it doesn't get discontinued.


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Old 08-11-2017, 10:21 PM
jimmontg jimmontg is offline
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The 80CRV2 I've read reviews on and promising it is, what I heard is it's a finer grained steel than 1084 which is OK by me. I didn't know CruforgeV has been discontinued as it is still for sale in a few places. Figured it would be hard to grind with that Vanadium in it. Well I'll take that off my list of steels to use.
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Old 08-12-2017, 11:32 AM
samuraistuart samuraistuart is offline
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Cru Forge V is simply an excellent steel. The knife makers didn't get on the bandwagon when it came out, and so Crucible decided it wasn't worth their effort any longer. I think it was discontinued right about the time I started in on this scene. And I've been trying to get Aldo and Chuck to stock a similar steel, like 1.2519 or 1.2442 (Tungsten instead of vanadium), but as of yet...nothing. IMHO, we NEED a higher performing oil quench tool steel. Not a fan of the current trend of higher carbide volume steels.

15n20 is another great performing steel often overlooked. That nickel content does magick!
80CrV2 is like 1080Cro Van. Excellent, fine grained, tough steel. Easy to HT and make a good blade from. W2 is a good steel as well. Nothing beat it for hamons (well, maybe Shiro/White steel!) O1 is easy to HT, but to get the performance it offers, you need to be able to soak at temp.
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  #15  
Old 08-12-2017, 01:21 PM
jimmontg jimmontg is offline
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Alpha Knife Supply has plenty of CruforgeV if you want to buy them out.


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