Damascus steel

[davidsuffolkParticipant @davidsuffolk]

While not really a ME question there are many on here with wide knowledge so can I ask for help with damascus steel?

I have bought some knife blanks in damascus steel & the patterns make the blades very attractive but I am told I will need to re-etch after polishing?

If I do that, how can I retain the high quality finish (I hope to achieve) while at the same time making the patterns in the metal distinct?

What acid is considered best for this and as it may not be easily sourced, where to get some? For what it is worth, I did notice that one drain cleaner I had bought was described as concentrated sulfuric acid so maybe more available than I suspect!

All tips and advice appreciated.

[davidsuffolkParticipant @davidsuffolk]

[KWILParticipant @kwil]

Try this, ferric chloride pcb etchant used.

**LINK**

[Brian WoodParticipant @brianwood45127]

Hello David,

I don't think concentrated suplhuric acid would be used for drain cleaner, it is potentially dangerous stuff used unwisely and in high strength a big problem downstream. Sodium Hydroxide pellets are more traditional for drains as that will shift fats and congealed organic oils.

For your etching I think you would find ordinary brick acid [Hydrochloric acid] will do a good etching job on steel and it is readily neutrallised after use with soda or bicarbonate of soda. I would experiment of some sacrificial pieces first to build up your experience.

As an aside, I did read that Damascus steel was at one time, long ago thank goodness, hardened by quenching in the bodies of prisoners in the belief that their souls became incorporated in the steel during this gruesome practice.

Regards

Brian

 

Edited By Brian Wood on 21/10/2015 10:14:21

[JasonBModerator @jasonb]

There was a thread a few months back about a guy blacksmithing a blade, and we talked about the correct acid to use there which enhances the pattern.

From using brick acid to clean up steel I doubt it will have the desired effect just leave a dull grey all over.

J

Edit, found the thread, If you go to Owen's web site it mentions the acid

http://www.model-engineer.co.uk/forums/postings.asp?th=106768&p=2

Edited By JasonB on 21/10/2015 10:18:23

[michael howarth 1Participant @michaelhowarth1]

Concentrated Sulphuric is/was sold as a drain cleaner in B&Q. Suitably diluted, I use it for pickling. I am pretty sure that they still sell it.

Mick

[AjohnwParticipant @ajohnw51620]

I'm sure it would leave a dull blade Jason that will also rust pretty quickly. Even the fumes can do this.

From watching Samurai I wonder if the OP has the process wrong. I'm thinking in terms of the bags of talc used on the blades. Maybe an etch is used and the blade then polished. The etch will enhance the pattern and then it's a case of how much so that it's still visible after polishing. I would have thought that there was some correct info on the web some where. Try searching with a .co.uk on the end or .fr if you can handle that language.

I'm sure I have read that quenching blades in people's bodies is a bit like case hardening.

John

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[Michael Cox 1Participant @michaelcox1]

A list of common etchant used for the metallographic examination of steel is given here:

http://www.asminternational.org/documents/10192/1756301/amp16006p042.pdf/f805348f-5422-4460-985f-36307cf4bbf7

I think what you really want is an etch that will reveals the grain boundaries and inclusions in the steel such as the nitric acid/ alcohol etch (nital).

Mike

[jason udallParticipant @jasonudall57142]

firstly..

Always check on somewhere inconspicuous.

that said I have seen lemon juice used to " etch" the grain of high carbon steel….

as you know .what you are trying to achive is emphasis of the different temper /composition of the metal..

.this has always facinated me..the temper of a billet is "detectable" by chemical action…

[AjohnwParticipant @ajohnw51620]

The OP might find some info around here or could even ask the person who maintains the site

**LINK**

It does mention the early use of citrus fruit juices. There may be more info around.

I used to shoot shotgun with some one who use one with a damascus steel barrel and thought there might be more useful information in that area. He was a brave person. The barrels have been known to burst. It had a semi shiny finish. Some others are rather spectacular. Very light and too much kick as a result for my tastes.

If I became interested in this I would want to forge my own mix of irons and steels.

John

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[Clive HartlandParticipant @clivehartland94829]

I was under the impression that the damascus pattern was caused by the joining of the metals when forged and that the darker areas were slag inclusions. Hence the unreliability of damascus shotgun barrels. Then, they made stronger barrels but painted on the damascus pattern. In any case shotguns with damascus barrels should only use low power shells or black powder shells.

The process of forging with the twisted metals was to bring out the patterns and if harder steel was included this could be brought to the cutting edge to make a sharp strong knife or blade.

Samuri swords are made this way with slabs of hard and soft steel which is heated and heat welded and then extruded by forging and this leaves a hard steel center as a cutting edge with softer outer sides that give strength. In the tempering the two steels react differently and this causes the classic Samuri curve in the blade.

Damascus blades are easy to sharpen and were preferred to single steel blades as they retained the edge better but would be sharpened on the go. I had one which the African askaris christened, 'Kisu Kali' as fierce knife. I did eventually bend it doing something and ruined it.

Clive

[AjohnwParticipant @ajohnw51620]

I understand that damascus blades were made in a similar fashion to the samuri ones Clive. A mix of iron and steel. Shotgun barrels too but the mix of sizes of iron and steel forged up were far more complex to get the various patterns. Some are then chemically treated to get various colours. There is an interesting example part way down this page. Might be called OTT damscus steel – done for ornamentation. It's initial aim was to combine the properties of the metals used.

**LINK**

John

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[JasonBModerator @jasonb]

If you follow the links I posted earlier you will see that the layers are made up from two different metals, one has a high nickle content like 15N20 that will resist the acid, the other just 20C will be darkened by the acid and that is what enhances the pattern

[AjohnwParticipant @ajohnw51620]

This is on original Damascus steel – the real thing. with plenty of technical detail.

**LINK**

This also mentions it along with the same problem, no one really knows how it was done and also the modern european way of making it – or something simllar

**LINK**

John

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[MikeParticipant @mike89748]

This is of n help to David in his quest, but Purdey are now producing a gun out of Damascus steel not made by the traditional forge welding process, but by a process involving making steel powders in a nitrogen atmosphere. The powders are then layered in moulds, in which they are melted together. This information came from a non-technical article published five years ago, and I don't totally understand how it works. What I do know is that in 2010 the gun cost £104,000! You can read the article at **LINK**

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