Case Hardening of thin sheet steel

[KentPDG]

I am interested in how to case-harden some very thin sheet steel. Specifically, 28 gauge (.015") low-carbon sheet, 1010 steel.

There is quite a bit of this material requiring treatment. I want to do it as a backyard project. The material will be cut to a specialized shape, then polished using various grades of silicon carbide. After that, I want to give it a very hard surface.

My initial thought is to build a special container of aluminum, place the parts inside (with suitable separation), and fill the container with powdered charcoal, possibly mixed with boron carbonate. This would be placed into a suitably sized firebrick oven, surrounded with charcoal. After igniting the charcoal, I would fan it with a blower or perhaps with compressed air.

After a period of heating (which is an issue where I need advice), the container would be removed from the oven and taken off of the steel parts. They would then be lowered into a barrel of very pure water, for quenching. After cooling, I would re-heat the material and air-cool it, for tempering.

The questions are:

1. Would this work, or have I missed something crucial?

2. Is there a way to limit the depth of the hardened case, or will this thin material just get hardened fully through?

3. Can I estimate the temperature inside the oven by monitoring the color of a sheet of steel above it? Or will I need to obtain a pyrometer? (I have one, but it only goes up to 800 degrees F.)

I would be grateful for comments, suggestions, and advice.

Kindly,

Kent

[Frosty]

Al won't work at al, it'll be a puddle long before the steel gets hot enough to case harden.

You can also try some of the commercial case hardening compounds like "Casenite". (sp?)

Why not make these from HC sheet in the first place? The appropriate alloy and proper heat treatment will give you the desired hardness and flexibility.

What are you making?

Frosty

[matt87]

From my notes, carbon will take 7 hours to migrate 1mm (0.039") at 870 degrees c (1598f), or 5 hours at 970c (1742f). If you can weld, make the containers from steel; it's cheaper and won't melt within the expected temperature range. Here is a guide which will indicate roughly what steel looks like when hot: Special Steel Supplier

Just to be clear, don't ignite the charcoal inside the containers -- it's only there as an inexpensive and relatively pure carbon source! You want the containers almost air-tight, to exclude oxygen but to allow the gases to escape non-spectacularly.

[ThomasPowers]

Note that steel will fairly quickly scale away in a forge. I've had case hardening runs where I could just twist the case apart with my hands when the run was over. Not a problem for ones and twos; but if you are doing a lot it will be.