Case hardening?

Am I right in thinking that case hardening of mild steel can be done by
heating the part up and dunking it in some oil? If so...
How do I know when the part is hot enough? Is there a standard(ish) colour
that I can refer to?
Will a hand blowtorch provide enough heat? Mine runs on a butane/propane
mix.
Would standard non-synthetic engine oil be suitable? Are there other
easily-obtained oils that are better?
How many times should the part be dunked in oil, and how long should it be
dunked for?
Cheers,
--
Wally
formatting link

Things are always clearer in the cold, post-upload light.
Reply to
Wally
Loading thread data ...
Alas, no. Mild steel doesn't have a high enough carbon content for this to work.
All is not lost, though, because you can get some carbon into it :
formatting link
jd
Reply to
John Daragon
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
Reply to
GPHawksford
Just for more info
Case Hardening compound can still be bought and is listed at
formatting link
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 :-
formatting link
The above seem to be from the 1924 Machinery Handbook
formatting link
Anyway hope this is of help. -- Cheers Adrian.
formatting link
Weekend Workshop
formatting link
Home made propane Foundry
formatting link
Learning CNC on a Vertical Mill
Reply to
Adrian Hodgson
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.
Mark Rand RTFM
Reply to
Mark Rand
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)
HTH
Tim
formatting link

Reply to
Tim Bird
In article , Mark Rand writes
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, etc...
Reply to
Frank Erskine
: In article , Mark Rand : writes : >: > : >>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..........
Reply to
Chris
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...)
Reply to
Martin Akehurst
Yes, as I intimated in a previous posting to this newsgroup, all of the old methods are dying out. Can't get the slaves these days...
Reply to
Martin Akehurst
: Yes, as I intimated in a previous posting to this newsgroup, all of the : old methods are dying out. Can't get the slaves these days... : But almost any carbon source, as others have mentioned, will work. I remember as an apprentice how slow it was waiting for for the carbon to migrate into the surface of the steel. Hours and hours for a few thous...... I would always prefer to use a hardening steel these days..
Reply to
Chris
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).
Noted.
-- Wally
formatting link
Things are always clearer in the cold, post-upload light.
Reply to
Wally
Bummer. Bang goes the easy method. :-)
Thanks for these - I'll have a look-see.
-- Wally
formatting link
Things are always clearer in the cold, post-upload light.
Reply to
Wally
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...
Mart
In message , Tim Bird writes
Reply to
Martin Akehurst
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...
Reply to
Martin Akehurst
Mild steel won't harden significantly with heating and quenching. One other alternative is Gunter's Superquench:
formatting link
Reply to
geoff_m
Has anyone in England discovered the products that would do this and are available over here? The ones mentioned are American commercial items.
-- Dave Croft Warrington England
formatting link

Reply to
Dave Croft
Dishwashing liquid I am sure you have. Dishwasher Rinse aid is the same as the Shaklee basic IIRC. A post on alt.blacksmithing should give you a lead. Geoffm New Zealand
Reply to
geoff_m
These days, it is more politically correct to plunge the sword into lawyers, politicians or people that generate SPAM and viruses...
Regards, Tony
Reply to
Tony Jeffree
I strongly disagree Tony. This far too politically correct and soft on SPAM and virus generators...
Reply to
Martin Akehurst

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.