I Thought It Was Mild Steel

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I Thought It Was Mild Steel

Postby Steve » Mon Jun 26, 2017 9:21 pm

So, I'm working on Tsuba Tutorial #2. Using the same steel that my previous six steel tsuba have been made from. Bought it from the local supplier off their "scrap" shelf (about 30x20x.5 cm and can't remember what I paid, but it wasn't much) and I thought it was mild steel. As a departure from my usual method of elbow greasing off the factory mill scale, I thought I'd pop it into the bbq and then quench it (there's still some scale, but seems easier to grind off - and I know there are chemical pickles, but I have none). I also spent some time hammering the surface to get a slight amount of undulation to help later with texture.

Anyway, unlike the previous tsuba, I was breaking blades like crazy. I thought I had a bad batch of blades (and you can't harden mild steel by quenching it, right?). After about 40% of the piercing was complete, I finally decided that there was a problem with the steel being harder and it couldn't be mild steel. So I put it back into the bbq and let it cool slowly to anneal it. Hopefully I can still decipher my punch marks to complete the cutting since the paper pattern has been burnt off.

I noticed something interesting on examining some of the pieces of steel that had already been cut off - there are distinct layers visible (visible because the cut surfaces are polished more than usual by the saw blades).

Any idea what kind of steel this actually is?
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Re: I Thought It Was Mild Steel

Postby Mac » Mon Jun 26, 2017 10:06 pm

Etch in acid and let's have a better look.
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Re: I Thought It Was Mild Steel

Postby Steve » Tue Jun 27, 2017 2:01 pm

Ok, so left the piece in vinegar overnight and no sign of any layers this morning. I also tried polishing (using natural stone) pieces of the same steel from other tsuba and there is no sign of any layers either. So, obviously those were just artifacts from the saw teeth (2/0) which is interesting given how uniform they were. Oh well.

Still don't know what exact type of steel it is, but it doesn't matter so long as I only work it annealed. Next time, if I get any mystery steel, I'll do some testing first :smash:
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Re: I Thought It Was Mild Steel

Postby tsterling » Tue Jun 27, 2017 2:26 pm

"Mild steel" is usually just recycled scrap steels. It has a set of minimum standards, but no maximum standards, so it can have a lot more carbon than you may expect. In the USA "A36" steel is this minimum standard stuff, but I've seen some you could actually make an acceptable knife blade from - depends on the luck of the draw. You would be better off finding some 1018 steel - it has low carbon, and isn't allowed to exceed that amount of carbon.

I don't know what a similar steel designation would be within European standards, perhaps someone else could enlighten us.
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Re: I Thought It Was Mild Steel

Postby Steve » Wed Jun 28, 2017 6:00 pm

tsterling wrote:"Mild steel" is usually just recycled scrap steels. It has a set of minimum standards, but no maximum standards, so it can have a lot more carbon than you may expect. In the USA "A36" steel is this minimum standard stuff, but I've seen some you could actually make an acceptable knife blade from - depends on the luck of the draw. You would be better off finding some 1018 steel - it has low carbon, and isn't allowed to exceed that amount of carbon.

I don't know what a similar steel designation would be within European standards, perhaps someone else could enlighten us.


That definitely must be the case here. I took a small piece of leftover and made a small tagane, which even when hardened and no tempering, dulled quite quickly in copper. So enough carbon to harden somewhat, but not anything like tool steel.

Now that I've annealed the tsuba blank, sawing is going incredibly well compared to before. Wish I hadn't wasted so much effort (and saw blades), but hopefully this experience will prevent the same from happening to other novices.
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Re: I Thought It Was Mild Steel

Postby tsterling » Wed Jun 28, 2017 7:02 pm

Yes. Decent steel isn't very expensive and will save you time and money in the long run.
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