To case harden mild steel you need to use a case hardeneing compound, available from most model enginering supply outlets. The object is best thoroughly cleaned, packed with the compund in an airtight container and then heated to red heat for an appropriate time depending on the depth of case needed. The whole lot is then quenched in water.The instructions with the compund should tell you more. Remember if you are making a small item you could use silver steel or gauge plate which can be hardened and tempered simply by heating / quenchcing / tempering. The old casenite compound was very good but is , I believe, no longer available due to health and safety reasons. Good luck
Case Hardening compound can still be bought and is listed at
if you do a site search for the stuff. There will be other suppliers as said below. But if for small parts and you can machine a tougher material then just mild steel EN1 etc, then follow the advise and go for a different material perhaps EN8 which I believe can be hardened with heat and quenching.
If you are into reading some articles, then try these links :-
The above seem to be from the 1924 Machinery Handbook
EN8 hardens pretty good in oil, I found old engine oil best, but it smells and produces loads of smoke, and is liable to catch fire if you have lots of bits to do in a small container (I used a tin plate over the top to kill the flames) EN16T hardens up even better in oil, it really depends on the application, one good thing about hardening a better quality steel in oil is you don't have to spend ages cleaning all the crusted on carbon after case hardening.
I used to use the above process to harden load cell cups for scales with capacities of up to 100 tons, with no problem, apart from the time I hardened a cup before I finished it an couldn't turn it to the finished size lol (EN8)
: >>To case harden mild steel you need to use a case hardeneing compound, available : >>from most model enginering supply outlets. The object is best thoroughly : >>cleaned, packed with the compund in an airtight container and then heated to : >>red heat for an appropriate time depending on the depth of case needed. The : >>whole lot is then quenched in water.The instructions with the compund should : >>tell you more. Remember if you are making a small item you could use silver : >>steel or gauge plate which can be hardened and tempered simply by heating / : >>quenchcing / tempering. The old casenite compound was very good but is , I : >>believe, no longer available due to health and safety reasons. : >>Good luck : >
: >I saw in a recent EKP catalogue that they claimed to have Kasenit, but I don't : >know if it's the 'real stuff' with the sodium hexacyanoferrate or not. : >
: Not *that* many years ago, case hardening used to be carried out with : chopped up bits of organic material such as horse's hooves, bones,
or by plunging a red hot sword into a slave..........
When I started in engineering 35 years ago we had a slower method - mixing salt and ground charcoal (barbeque charcoal not briquettes), with the item in a small tobacco tin, then heating for 1/2 an hour to an hour or so.
Packing the tin with charcoal in a barbeque with all the vents open would probably work. Then take out, clean and heat to red heat and quench in oil or brine. Don't use water as the cooling is too quick and as you'll have a 'soft' centre and hard 'case' it can distort or crack.
We only used small amounts so it wasn't worth searching out Kasenite or similar
Incidentally the 'thistle shaped' barbeques are also good for heat treating (long soak for rolled 'bright MS before lots of machining to stop distortion) Oh, and also for stir frying...
The chopped up 'organic' soup used to be used by blacksmiths for dunking bright red steel to get a hard surface. I remember this when I was very young ... and also the revolting smell from the 'organic bits' repeatedly heated and cooled over years in the blacksmith's shop. It used to be old bones, horse hoof clippings and usually a few 'other bits' particular to the blacksmith (no, you don't want to go there...)
That's the sort of timescale that seems okay to me. What was the ratio of salt to ground charcoal? Any idea what depth the carbon would penetrate to?
I don't have a garden or a yard, so using a barbie is out. I was thinking of using a petrol-fueled stove in the doorway of my garage. Would that produce enough heat? (Small parts, by the way - M6 bolts at the moment).
Things are always clearer in the cold, post-upload light.
Be careful with 'old engine oil', especially with cars that have mechanical fuel pumps. You can get a lot of 'light chain' oil after a while and if there's a mechanical pump working off the camshaft (esp. older / classic cars) you can get petrol leaking into the oil as well.
Been there, and the eyebrows have now grown back except at full moon...
Hmmm. Roughly one part salt to three parts finely ground (coffee grinder when the other half is out for long enough to clean it thoroughly) charcoal.
You need to get it at least dull red for half an hour. Probably not petrol stove. Suggest large tin full of holes. Pack tin containing mix/parts in larger tin with charcoal. Set light to charcoal and go for a long coffee...