The Riddle of Steel?

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Good evening my friends and fellow oil lovers. It's a soft and rainy evening here in Central Florida, which gives me time to pause and ask a question. So like Paul Newman and Robert Redford in "The Sting," I begin with -

"The set up."

Not too many months back, I became the proud owner of an ancient and well worn piece of farming equipment know as an "Acme Harrow." These were popular devices decades ago but have largely fallen out of use with the advent of tractors. While I won't go into too much detail on what it does or is suppose to do, I will tell you what it's not doing and why.

It's not working. The reason it's not working is that the long drawbar that sets the depth of the tines is bent is several different directions. How this happened I have no idea, nor is it important in the telling of this tale. The simple fact is, it's bent in about five different places making it go in five different directions while it's suppose to be straight as an arrow.

Here's what I did. I built a fire. I mean to say, I built a BIG HOT fire with oak firewood. (I should make a "Quest for Fire" reference, but I can't think of one since they mainly just grunt in that movie). When it was blazing hot, I threw the draw bar into the midst of the flames. Since I didn't have a sexy babe dressed in a leather outfit to work the bellows, I resorted to running a pipe into the middle of the hot coals and connecting said pipe to an air compressor. When I turned on the compressor, it re-created the 1949 James Cagney movie title all around the metal bar, (for effect, I even shouted, "Look Ma, top of the world!").

After a period of time, (aka, two bottles of beer), I drew the bar out of the fire and laid it on an old tractor wheel weight I use as an anvil and thought of the opening scene of "Conan the Barbarian" while I worked the metal straight and true, ( I did not, however, carve said bar with any runes dedicated to "Krom").

Now then, here's my question. I don't want the metal to be too hard for fear it might break at some point after I re-attach it to the harrow. Neither however do I want it too soft for fear it will bend. I can easily build another fire, re-heat the metal and quench it cool to temper it, but how hot should I get it and how much should I cool it to make it not too soft but not too hard. There's a ditch filled with water not far from my work area into which I can cast this "Excalibur," I just don't know when to throw it in or how long to wait before the "Lady of the Lake" throws it back.

I really need help from you guys since Conan's dad never shared the "Riddle of Steel" before he was eaten by the dogs.

Said shaft is about five feet long, three inches wide and one inch thick.
 
First you need to have an idea of what sort of steel it is...
Khalkeus, (at least in Gemmell folklore) would have known a little.

but he never had an angle, or a bench grinder, with which to discover a few more of steel's marvels.

2-7_spark_patterns.jpg


Get a handle grinding on stuff that you know is what you know it is, and then compare what you've got.

Will likely be wrought iron(ish)...can be hardened some with a water/oil (or air) quench, then would need tempering, could be done with a gas flame/torch, rather than fire.

Quench it in urine, and you can add some nitriding, ala vikings allegedly did.

Better off just letting it cool somewhere with no draughts instead.
 
Originally Posted By: GreeCguy
Said shaft is about five feet long, three inches wide and one inch thick.


Originally Posted By: Shannow
Quench it in urine, and you can add some nitriding, ala vikings allegedly did.


Better drink a lot more than 2 beers before taking on that task.
lol.gif
 
Didn't Thulsa Doom answer the riddle? Either way, you better figure it out or else Crom will laugh at you and cast you out of Valhalla!
 
Originally Posted By: GreeCguy

Now then, here's my question. I don't want the metal to be too hard for fear it might break at some point after I re-attach it to the harrow. Neither however do I want it too soft for fear it will bend. I can easily build another fire, re-heat the metal and quench it cool to temper it, but how hot should I get it and how much should I cool it to make it not too soft but not too hard. There's a ditch filled with water not far from my work area into which I can cast this "Excalibur," I just don't know when to throw it in or how long to wait before the "Lady of the Lake" throws it back.

Said shaft is about five feet long, three inches wide and one inch thick.


Too many unknowns here to give really specific advice, but I can write a little about the heat treatment of steel. The basic way that low alloy steel is hardened is to heat it to orange heat and quench it in brine, water, or oil. (What medium is used depends on the steel alloy, and how thick the workpiece is.) Then after the workpiece has cooled to below ~200F in the quench medium, reheat to some temperature between 350 and 1100F to temper it. The higher the tempering temperature, the softer the steel will become, and the less strength it will have. For any given steel, you trade off strength for toughness as you temper at successively higher temperatures. At a minimum, reheat to 350F to relieve internal stresses caused by the quenching, and let the workpiece cool to room temperature in still air.

The big unknown here is that we don't know what kind of steel it is, or even if it is steel at all. If it is wrought iron, which doesn't contain carbon, you can quench it, but it won't harden.

Given that you have a water-filled ditch, you already seem to be set up for quenching, but don't just throw the orange-hot shaft into the water and let it sit. That amount of heat will boil the water surrounding the workpiece, and prevent the rapid cooling that makes an effective quench. After plunging it into the water, agitate the shaft vigorously to keep liquid water against its surface for maximum heat transfer.
 
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