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case hardening?


integerspin
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Does any one regularly get case hardening done and could they add some stuff of mine?

I made some spacers for a gearbox, must be a few years ago now, and never got the case hardening

sorted as it turned out my local hardening place didn't do it any more.

I am just making some dies for a hydraulic crimper, I guess they should be cased as well and

thought I would ask here before I started making a furnace;-)

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  • 3 weeks later...

Carbon = coke. Grind it up into a very, very fine powder -- ideally the same consistency as talcum, if possible add a small amount of soft iron fillings that you have filed off say a piece of mild steel pipe, but no more than 20%. Heat your piece until it is bright cherry red, fully immerse it in the powder and allow it to cool down. Test it with a pin punch (before & after is a good plan) and you will see the external case of your piece has absorbed some of the carbon and hardened.

If you want to get really special and can legally obtain some liquid arsenic -- add some to your carbon powder until you have a thin paste, remember arsenic is a poison and wear protective gloves while mixing the paste, Immerse your red hot piece of steel fully into the paste. DO NOT INHALE the fumes while the piece is cooling down ! It is poisonous! If you do this form of case hardening you must wear a full breathing apparatus and carry it out in a mechanically ventilated workshop or better still inside a fit-for-purpose fume cupboard.

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Carbon = coke. Grind it up into a very, very fine powder -- ideally the same consistency as talcum, if possible add a small amount of soft iron fillings that you have filed off say a piece of mild steel pipe, but no more than 20%. Heat your piece until it is bright cherry red, fully immerse it in the powder and allow it to cool down. Test it with a pin punch (before & after is a good plan) and you will see the external case of your piece has absorbed some of the carbon and hardened.

If you want to get really special and can legally obtain some liquid arsenic -- add some to your carbon powder until you have a thin paste, remember arsenic is a poison and wear protective gloves while mixing the paste, Immerse your red hot piece of steel fully into the paste. DO NOT INHALE the fumes while the piece is cooling down ! It is poisonous! If you do this form of case hardening you must wear a full breathing apparatus and carry it out in a mechanically ventilated workshop or better still inside a fit-for-purpose fume cupboard.

Have you got that mixed up with cyanide?

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Nope, arsenic - one of the metallurgy subjects we covered when I did my B.Sc. many, many many years ago. I've done it since on a new gear selector block that I've purchased for my Disco, the original one had worn grooves in it corresponding to the reverse light switch plunger resulting in the switch not operating. It annoyed me somewhat that the original part isn't case hardened to prevent such an eventuality.

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I just read the Beagle article, it's very good and comprehensive and essentially the same as I described for case hardening I'd agree however that the components would be easier to obtain, to purchase liquid arsenic I believe that you may need some sort of licence.

Coke as a form of carbon is for me easy to obtain and I grind it down in an old stone pestle and mortar. You could also go to your local art supplies shop and buy some charcoal drawing "sticks" they would achieve the same result. The essential thing is to get it ground down as fine as possible, the arsenic (in my case) is simply a liquid medium used to further dissolve the carbon dust so that it will penetrate the surface of the heated job piece.

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