Surface hardening

[mookiie]

Could someone explain the materials/tools that are needed to surface harden a piece of metal, as well as the process involved?
Thanks!

 

[rcmodel]

A torch & this:
http://www.brownells.com/.aspx/pid=27119/Product/SURFACE-HARDENING-COMPOUND

rc

 

[Fleet]

Get what RC shows. Heat the metal red hot, dunk it in the case hardening compound. If it's something small like a pin, you may have to do it a couple of times. You might also consider tempering vice surface hardening.

 

[mookiie]

Your tHe best RC! Thanks for the quick response!

 

[mookiie]

Can anyone say if it is better to quench in water or motor oil after heating? I believe that using oil makes the metal harder, but also more brittle - is this correct?

 

[rcmodel]

No, cold water does that.

An oil quench should result in a slightly softer less brittle part.

rc

 

[mje]

Depends on the type of steel. Some are best quenched in oil, like O-1 steel, and some in water. Oil does't carry heat away as quickly, but it cools more evenly. When water boils it creates bubbles that insulate areas of the part.

But any steel can be hardened in either material if it has a high enough carbon content.

 

[mje]

BTW, you can also accurately judge if you've heated a piece enough by testing it with a magnet. At the temperature where steel loses its ability to be attracted to a magnet- the "Curie temperature"- it can be hardened.

 

[rcmodel]

I didn't think the op was asking about tempering air, oil, or water harding tool steel.

I thought he was asking about using Case Harding Compound to harden the surface of the part.

Maybe more clarification is needed as to what it is he wants to do.

rc

 

[mookiie]

RC - You are correct, I am planning to use the Case harding Compound to harden a part surface. Just wanted to see what it should be quenched in, and by the above responses I am leaning toward water. Thanks

 

[Zeke/PA]

To Surface/Case harden a part , the part must be "quenched" in an appropriate commercially available compound.
A "water" OR "oil" hardening alloy should be "quenched" accordingly BUT a "draw" is in order also.
"AS QUENCHED" is usually too hard for practical use.
It's called the "harden by eye " tecnique and it DOES work but a "draw" is required.
For small parts, a Mapp bottle is O.K. OR OX/Acetleyene.
For BEST results, the alloy SHOULD be known.
Surface or "case" hardening can REALLY be done on Low Carbon stock and NO FURTHER heating OR quenching is required.
The most important thing though is to READ and FOLLOW instructions/ directions.

 

[Zednut]

You need to pack the steel with Kasenit or Casenite. The length of time you hold it at heat determines the depth of the hardening. Typically this is used on steel with lower than normal carbon content.

It is best to know what metal you are using precisely before hardening. Disasters can happen. For eg, If you heat up A2 (air quenched) steel to the hardening temperature and accidently quench it in water or oil like you would for O1 or W series steel...it will instantly shatter like broken glass.