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Jake Wilson





Joined: 08 Sep 2009

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PostPosted: Tue 08 Sep, 2009 8:06 pm    Post subject: working hardned bar stock         Reply with quote

OK folks. I have something I have been meaning to try, but it seems so simple and idea, there must be something I'm missing.

I am not set up presently to heat treat steel, so I was thinking of purchasing a piece of damascus bar stock, having it hardened to around HRC 28, and then just working it by stock removal, and then polishing and etching it.

Why will this not work? It seems like it would make a historically accurate sword as far as hardness and toughness, based on an article read here on the site. Granted, it's not ideal, but it does permit the making of a sword with at least some hardness/toughness without the need for further heat treating.

Also, if I can't find damascus bar stock that fits my needs, would this method work with a 1050 or 1060 steel?

Thanks,
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Jared Smith




Location: Tennessee
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PostPosted: Tue 08 Sep, 2009 8:31 pm    Post subject:         Reply with quote

It does not sound like an easy idea overall. You could opt to send the ground blade off to someone else for the heat treat. I would expect a sword sized piece of pattern welded stock to be pretty expensive too. If it is your first try at it, 1085 or 1095 with someone else doing the heat treat may be considerably cheaper overall than the premium raw stock for a "damascus" blade.

Many pattern welders don't really do a thorough anneal after forging the material, and I would guess you may be looking at Rc 20 to 25 on "as forged" raw stock with some sort of very simple normalization ... allowing it to cool in the forge when done. (Tend to need bimetallic blades to cut flat stock very well. Grinding is also noticeably tougher than store bought annealed materials.)

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Doug Lester




Location: Decatur, IL
Joined: 12 Dec 2007

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PostPosted: Tue 08 Sep, 2009 9:13 pm    Post subject:         Reply with quote

HRC of 28 is real soft and will not support a cutting edge. Hardening and tempering a blade is not rocket science and can be done with a propane torch a deep kettle of oil (like a turkey frier), and a kitchen oven, or use the propane torch again. Give us an idea of what you want size blade you want to make and there are those of us who make blade can give you ideas of how to heat treat on the cheap.
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Jake Wilson





Joined: 08 Sep 2009

Posts: 11

PostPosted: Tue 08 Sep, 2009 9:37 pm    Post subject:         Reply with quote

About 26 inches long, viking pattern blade. plus the tang so about 31 inches total probably. I found a place called twofingerknife.net that sells pattern welded bar stock, and I figure I could use that for a nice blade. Depending on price, I might get some 1050 as well from admiral steel.

So the heat treatment is not terribly difficult? A lot of what I read makes it appear to break blades with surprising regularity.

Also, in the article here about old swords:

http://www.myArmoury.com/feature_bladehardness.html

The colored lines on graph 2 look to average to a HRC of about 28? Was this not typical of the period blades?

Looking back to an older post I was reading about taking modern smiths and "dropping them into the period", it seems to me modern blades are FAR superior to period blades. When you can buy a whole piece of stock with consistent properties.

Is the pattern welded steel heat treated in the same fashion as the homogeneous materials? Do you heat treat pattern welded steel based on the curves for the higher carbon steel in the mix.

Thanks for the replies.
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Jared Smith




Location: Tennessee
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PostPosted: Wed 09 Sep, 2009 2:14 pm    Post subject:         Reply with quote

I would agree that modern blades meeting our expectations of high quality reproduction quality are not lacking mechanically in comparison to historical ones. The trick with a true sword length object (a piece 31" long in your case, or longer in many historical cases) is having large enough equipment to reliably anneal, heat treat, etc. The raw damascus stock can be welded up in regions just 8" in length. If you ask your source, they may be able to do a fair anneal (probably 3 successive normalizing cycles) if they have large enough coal forges or some sort of suitable sized salt bath or heat treating furnace. 31" length will probably will be a few inches long to fit in a typical kitchen appliance oven. Also, spring tempering temperature appropriate for a sword will almost certainly entail heating it above 600F, (many of the pattern welded combinations seem to be taken to 700 to 800F range for sword / spring temper purposes.) Few kitchen ovens if any could safely do this. If you limited the project to a longseax (maybe 18" blade, no more than 24" total length), and accepted a stiffer final blade, it would be easier to pull it off with improvised home heat treat.
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Jake Wilson





Joined: 08 Sep 2009

Posts: 11

PostPosted: Wed 09 Sep, 2009 6:13 pm    Post subject:         Reply with quote

OK I'm convinced, I am planning to build a simple charcoal forge on the ground. I figure some brick, some sand as insulator on the outside and a load of charcoal. I don't know exactly what to use for a blower, but I'll figure that out. A few questions for you folks.

1. Once the blade goes into the fire, about how long will it soak until it gets ready to quench?
2. Should I simply check it with a magnet to see when it's ready?
3. How long do I have after I decide to take it out of the fire...a few seconds before it starts to precipitate the cementite or the ferrite depending on content?

I guess the only purpose of the heat treat is to form martensite, right? Fine grained pearlite is quite strong and durable. Why is air cooling never used to make a fine grain pearlite blade?

Thanks
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Maurizio D'Angelo




Location: Italy
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PostPosted: Wed 09 Sep, 2009 6:29 pm    Post subject:         Reply with quote

Doug Lester wrote:
Hardening and tempering a blade is not rocket science and can be done with a propane torch a deep kettle of oil (like a turkey frier), and a kitchen oven, or use the propane torch again. Give us an idea of what you want size blade you want to make and there are those of us who make blade can give you ideas of how to heat treat on the cheap.


Hello,
I do not agree. Heat treatments are a technology.
You can hardening and tempering with propane torch and oven cooking.
But, the results are not predictable and repeatable.
The blade can be decarbonized in some places.
Deformations can be large.

If you really want to do by yourself: vertically hardening , vertically cool,
tempering with two horizontal bars for support.

I hope that this is a little help. Happy
Ciao
Maurizio
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Maurizio D'Angelo




Location: Italy
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PostPosted: Wed 09 Sep, 2009 6:45 pm    Post subject:         Reply with quote

Jake Wilson wrote:

3. How long do I have after I decide to take it out of the fire...a few seconds before it starts to precipitate the cementite or the ferrite depending on content?

I guess the only purpose of the heat treat is to form martensite, right? Fine grained pearlite is quite strong and durable. Why is air cooling never used to make a fine grain pearlite blade?

Thanks


I would not talk of transformation of carbon in relation to cooling rate.
I do not think of the precipitation of cementite, pearlite, martensite.
I think a speech too technical for the means used.
What God will give us will be good.
Ciao
Maurizio
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Jared Smith




Location: Tennessee
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PostPosted: Wed 09 Sep, 2009 9:07 pm    Post subject:         Reply with quote

Jake Wilson wrote:


1. Once the blade goes into the fire, about how long will it soak until it gets ready to quench?
2. Should I simply check it with a magnet to see when it's ready?
3. How long do I have after I decide to take it out of the fire...a few seconds before it starts to precipitate the cementite or the ferrite depending on content?
Thanks


Before you spend any money, please check with your local region's knife maker guild, "damascus" material source, (ABANA or equivalent) and inquire if there is someone already experienced in and roughly equipped for heat treating objects of this size. They will most likely exhaust themselves to make sure you do not waste money, waste someone else's hard labor-exotic material, and to ensure that you don't end up in a hospital. I would be surprised it they did not offer to host you at their facilities, if they have them, to ensure that you do not create a catastrophe or failed project.

How long it needs to soak depends a lot on the heating method. 5 minutes in a molten salt bath, or 20 to 30 minutes surrounded in a furnace after being brought up to temperature along with the warm up period are roughly the extremes for a sword thickness object.

Many have used magnets. But, I suspect they know from experience that they are close before they even begin checking. You can only breifly tap with a touch stick mounted magnet. Magnets demagnetize quickly at much lower than appropriate temperatures (curie temperature.) I would not assume that the magnet can be submersed for something like a minute until contact forces decrease as a test. Heating, even at the ideal temperature, for an excessively long period of time is considered "bad" too, as it leaves coarser grain structure.

To get to the point, you don't have a lot of time to fool around with quenching it. If you have a very forgiving steel you may have around 8 seconds to get it quenched to below 400 F from the time you pull it out of the quench pre-heat. The worst case might be 1.5 to 2 seconds if it is low to mild carbon with alloys that don't help. Most quenching pattern welded "damascus" use low viscosity "fast quench" oils. Water might work if you are lucky, but could crack the blade. Lard or bacon grease mixtures, used transmission oil or peanut oil are the cheapest, likely to work fluids, if you have the necessary quantities available, but, can be very flammable and dangerous to your flesh and respiratory system. Oils commercially prepared for quenching (low flash, low fume, parafine mineral oil based, 5 gallon minimum order Houghto Quench G, other brands repackaged by some vendors for bladesmiths) for this are not cheap, and in a 5 gallon pail, will cost you enough to at least consider hiring someone else to heat treat it though. There are some "rules of thumb" as to the gallons of oil per pound of material to be quenched. Distributors of commercially prepared quench oil will provide you with some guidance if you take the time to inquire and clarify how you intend to use it.

Absence of evidence is not necessarily evidence of absence!
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