Case Hardening – can’t even harden a washer !

[C WParticipant @cw29454]

Well after an hour and a half, it’s harder, but not what I would call hard. You can still file it or scratch it with a scalpel but a stainless steel kitchen knife won’t touch it. Am I expecting too much ? Hopefully the Blackgates compound will be a different tail.

 

EDIT. I take the above back, when filing it back to back with a standard washer it is a fair bit harder. Not untouchable by file as I have seen it described on the net, but much harder work to remove any material.

Cam.

Edited By C W on 29/06/2011 18:36:46

[Clive HartlandParticipant @clivehartland94829]

I would then suggest that the washer is made from some type of inferior steel sheet, it is after all only a washer!

 

Please try to harden a piece of machined steel that has been made to do something like a bush or a flange. It need not be a big thing so make it about 1″ dia with a bushing and a flange.

Drill a hole through it and try again.

 

Clive, PS you might be able to use it later as a guide when drilling something.

[C WParticipant @cw29454]

Went to a local forge up the road today, got some mild steel bar, but the guy had no clue as to what grade of steel, so no better off really, mind it was free so not all bad.

 

So where would you guys send me to get some steel in small quantities of a known grade such as:

 

080A15

024M10

210M15

214M15

EN32B

EN32M

EN202

Apparently these are all suitable for case hardening.

 

Cam.

Edited By C W on 30/06/2011 15:41:54

[Michael Cox 1Participant @michaelcox1]

Hi CW,

I always buy metal from m-machine (http://www.m-machine-metals.co.uk). Very helpful people and can sometimes get special grades on request.

Steel washer are probanly stamped from a cheap grade of steel like EN3. This should be case hardenable. Steel from the local forge is likely to be cheap EN3 also.

Mike

[jomacParticipant @jomac]

Hi, saw an old recipe for case hardening a few years ago, that contained, charcoal, bone, horn, ground up leather, ( use the wifes grater ) that was mixed with molasses to a thick paste, the sugar in it turns to carbon,?????, have not needed to case harden yet, but might try this method as I think the molasses would stick to the job better.

John H.

[Ian S CParticipant @iansc]

Went into christchurch today (I don’t go often, its a bit of a desert these days, buildings down etc), was in one of our leading engineering retailers, and found a 1 lb tin of kasenit on the shelf for $NZ 74. 45, so it’s available in New Zealand at the moment. I did’nt buy any, as I have 3/4 of a tin I bought at the same place 25 years ago. Ian S C

[Gordon WParticipant @gordonw]

I remember reading that would be escapees in German prison camp case hardened some home made tools by packing in sugar and putting in the stove. Sugar has lot of carbon of course.

[Steve WithnellParticipant @stevewithnell34426]

Posted by C W on 28/06/2011 21:02:39:
Just tried washer No2 in a little container with enough powder to coat it, and blow torched it for 5 minutes or so. Result was no different unfortunately Suspect I didn’t get it/keep it hot enough. Off tomorrow to buy some BBQ Charcoal I think, will report back.

Doesn’t the blow torch simply blow the Eternite away? I’ve used this stuff and have had hit and miss results to be honest. I’ve tended to pack the part into a tin and heat it to “carrot” for a while, then left it to cool. Then re-heated the part directly to “carrot” and immediately quenched. Works but I do not get good consistent results.

[C WParticipant @cw29454]

Well my hardening compound from Blackgates arrived. Within 5 minutes I had created a washer harder than the eBay obtained Ethernite produced in 1 1/2 hours. Much much better stuff.

 

And I can confirm it’s the type that sticks and it contains Potassium Ferrocyanide.

 

Thanks for all the help guys !

Edited By C W on 04/07/2011 22:28:02

[Cyril BonnettParticipant @cyrilbonnett24790]

May be useful to know that many gunsmith companies sell these products

http://www.blackleyandson.com/acatalog/Compounds_and_Solutions_for_Metals.html

http://www.peterdyson.co.uk/acatalog/METALWORKING_PRODUCTS.html

[Steve WithnellParticipant @stevewithnell34426]

From Blackleyandson website:

 

“FILL CONTAINER WITH TWO PINTS OF TEPID WATER. ADD ONE TABLE SPOON OF SALT PETRE AND MIX. HEAT PART TO RED AND DIP INTO COMPOUND. REHEAT PART AND ALLOW THE COMPOUND TO MELT AND FLOW OVER SURFACE OF PART, AND PLUNGE INTO WATER. WASH OFF REMAINING COMPOUND”.

 

What’s the purpose of the Saltpetre in the quench?

 

Regards

 

Steve

 

 

 

[John Stevenson 1Participant @johnstevenson1]

Posted by Steve Withnell on 05/07/2011 22:20:21:

 

What’s the purpose of the Saltpetre in the quench?

 

Regards

 

Steve

 

 

 

It replaces the virgins blood that was used years ago seeing as the last know sighting of a virgin in the Midlands was on the Cadbury works outing in1937.

 

John S.

[Chris TriceParticipant @christrice43267]

I don’t have an exact answer Steve but I know traditionally there’s a history of using salty brine to quench with. It apparently gives better results. Might have to dig out the ol’ hardening and tempering metals book.

[Chris TriceParticipant @christrice43267]

Suitably inspired by this thread, I had a go for the first time using the powder from Blackgates. Easier than I was anticipating. I was heating a freshly turned piece of mild steel about 14mm diameter and about 30mm long. Heated to bright orange/carrot, dipped it in the powder and made sure it had a good coating then returned it to the firebricks and continued to heat it and keep it bright orange for aprox 5 minutes before quenching it in brine. Cleaned all the gunk off with a fine steel brush and tested it with a file. Clearly much harder to the point where I didn’t want to push it too far for fear of taking the edge of the file teeth. The salt in the brine BTW apparently delays or helps to stop the formation of steam bubbles on the surface of the metal as it’s quenched.

[Chris TriceParticipant @christrice43267]

…And coating the hot item in powder reminded me of silver solder flux but black and more granular instead of white and powdery. It melts and bubbles in a similar way before solidifying into a crust around the workpiece.

[mgjParticipant @mgj]

I don’t normally come here but……

 

We have got ourselves in a mighty tis was, and it might be worth reading Hardening and Heat Treatment more carefully.

 

Basically there are two separate processes.

 

There is the the slow carburisation process, which involves old bits of bone, leather etc, and more “modernly” various carburising powders. The process involves (normally) sealing in some airtight box, (not always depends on the powder)raising all to the appropriate temperature and then iron being a solid solution, the carbon migrates through the material at a particular rate enriching the surface with carbon before being quenched. It is slow, but depth of case can be more or less as deep as you want, properties are very controllable and there is les risk of distortion. Much used in industry.

 

The other is the Kasenit type process, much more suited to our sort of setup and effective enough for what we want.

 

Nothing inferior about anything, nothing went wrong – just a case of the right powder for the wrong process or vice versa. Full details are in Tubal Cains book in the chapter about case hardening.

 

Brinne is a good idea if you are stopping a tempering/heat treatment process (at say light straw), or if distortion is likely to be a problem – mostly it isn’t because the substrate is in our cases mostly non heat treatable mild steel. We don’t really toughen or otherwise heat treat solid steels other than Silver steel.

 

It has little effect on case hardening because all one is doing is freezing the crystal structure in the martensitic condition. IOW you are stopping the carbon rich surface from transforming back into pearlite, which it will do if allowed to cool naturally. So as long as you cool it faster than it can transform, and that you will do with water, the system will work perfectly.

[Chris TriceParticipant @christrice43267]

Being new to this I’m a bit lost. Isn’t the Kasenite doing the same thing but more quickly? The instructions say heat for between five to thirty minutes depending on the thickness of the casing required. Whatever is in it must be migrating into the surface of the steel or is the chemistry different?

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