Case Hardening info needed---

[delaplume]

Yesterday one of our club members came up with the idea that you can case harden using Fryolux as the hardening compound !!................... Does anyone know about this ??-------Can it work ??---- I can't see that a soft soldering flux is high in Carbon content unlike ground animal bone etc....

[houstonceng]

It used to be advertised, by its manufacturer, that Fluxite paste ( essentially Zinc Choride in a paste used as a soft solder flux) was, also, a case harnening compound. Can’t see it myself, however, the formulae May have been different back in the late 1940s and early 1950s.

Try a sample test and see ?

Best CH compound, Casenit, containing a number of noticing chemicals as well as carbon, is no longer sold. Not due to H&S as some said, but just because industrial use is non-existent and production for amateurs is not cost effective.

[silverfox]

A question i was about to ask

1) what is available to do case hardening nowadays

2) best way of using items in 1)

[Oily Rag]

Sept 15, 2018 19:22:45 GMT silverfox said:

A question i was about to ask

1) what is available to do case hardening nowadays

2) best way of using items in 1)

I have used
www.minitech.com.au/cherry-red-case-hardening-compound-400g
as per the instructions on the container
Heat to bright red, more like orange in low light.
Drop into the Cherry Red Compound.
Let cool
Cook up again and quench in water.
My little pins on my 32mm steam took a skin. How deep, I know not.

[jools]

I always wondered if scungy old black mineral engine oil would be of any use ? plenty of absorbed carbon in there ......

[92220]

I've got casehardening compound (powder) from both EKP and Blackgates. Both products work equally well.

Bob.

[delaplume]

Thank you all very much indeed for those useful replies.........Yes, eventually I will try both the flux and Blackgates powder on some 1/4" dia BMS pins but at £13.60 for 400g from Blackgates that will have to wait a wee while................unless someone out there has some spare samples of both and wouldn't mind doing a bit of experimenting ?

[silverfox]

Oily

When you dip it in the powder. is the powder still in the tin?

dumb question but i have to ask!!!

and a +1 for the replies

[simplyloco]

Sept 20, 2018 9:29:45 GMT silverfox said:

Oily

When you dip it in the powder. is the powder still in the tin?

dumb question but i have to ask!!!

and a +1 for the replies

I used to find a suitable steel container with a tightly fitting lid, e.g. a tobacco tin. Encase the item in the tin with the powder and skim the top flush. Replace lid, and heat to cherry red for however long the instructions dictate. Leave to cool. Harden as desired. The 'skin' method ain't durable in my view.
John

[92220]

I have an old stainless drinking mug that I tip the powder into. I then just bury the red hot item in the powder using an old pair of long nosed pliers that I use to pick up parts that have just been silversoldered. When all finished, I just tip the powder back into the original pot. I have used an old glass jar as well, and the heat had no effect on the jar. I suppose the powder insulated the glass a bit.

Bob.

[silverfox]

Bob

so the order is

Fill a jar or enamel mug with powder
heat the part reqd, in my case it is the pin holes for the valve gear, until it is cherry red
and then poke this into the jug with the powder
let it cool
heat to cherry red and quench in water

added...put excess powder back in container

clean up

[92220]

Hi Ron.

Yes that's it. Exactly what I do. If it's just the pin holes you want to harden, place the part on a fire brick or similar. fill the pin hole with case hardening powder with a little bit on the outside face of the part, and heat to red heat. Then tunr the part over and fill the pin hole again, and a little case hardening powder on the outside face that is now the top face. Allow to cool and stand till cold. Re-heat to cherry red and quench. This should then give you case hardened holes and a small hardened patch on both faces around the hole. The rest is still soft so is still able to be machined if needed.

Bob.

[silverfox]

Bob

Thank you for 'holding my hand'

despite me being at this for God Knows how long, it is only in the last few years i am making progress like 'the big boys'

Thanks again

Ron

[Jim Scott]

I knew I had some Kasenit somewhere in my workshop and eventually I turned up that familiar washed out yellow tin with black lettering as shown on this web photo.

However, I recall that every tin I've seen has been seriously affected by corrosion, as is mine.

After opening the tin an removing the contents, lightly brushing off the corrosion resulted in gross perforation of the tin.

The corrosion is probably due to the the contents being slightly hygroscopic but this doesn't seem to have had any visible effect on the condition of the powder.

I have used EKP's CH compound as well and of course it produces a hard surface. However my impression is that Kasenit adheres to the hot steel better and gives a 'better' case. Totally subjective I know - no careful evaluation has been done, its just a feeling.

92220 describes on Sept 21 probably the best method for most folk, but the depth of hardening will be very slight, in terms of maybe .001" to .002". Cleaning off the crust then repeating the heating and dipping procedure several times before finally heating and quenching will increase the depth of carbon enrichment a bit more, perhaps to .003" to .004" (if you're lucky).

Simplyloco (Sept 20) points this out when he says that 'the skin method ain't durable in my view'. His traditional technique of packing the object in a sealed box surrounded by case hardening compound will give a much greater depth depending mainly on how long the whole box is kept at temperature. Even so, after say 1 hour at temperature, the carbon may not have diffused to more than .010" deep but this might be perfectly acceptable on say 0.25" dia. The negatives are the requirement to heat for a long period, usually requiring a furnace of some sort. Plus the use of much greater amounts of carboniferous material to fill the box.

Delaplume, if you haven't been able to source any of the alternatives, PM me and I will send you a sufficient amount of Kasenit for your immediate needs.

Jim S

[92220]

As Jim says, the method I described only gives a very shallow hardened layer. The method was described for hardening small holes, but for greater depth of hardening, repeat the process a number of times. However, most case hardening only gives a 0.001" to 0.002" deep layer, and 0.002" can take up to 20 to 30 minutes at red heat, to achieve. Anything deeper requires much longer in the compound, at bright red heat. 0.01" deep is industrial depth. When I worked in the drawing off of Delapena Honing Equipment, it was very rare to specify hardened depths of more than 0.003", except on heavily loaded surfaces. We didn't use Kasenit though. Parts were immersed in red hot cyanide baths, for up to 5 hours for the greater depths. Definitely not a process for the model engineer!! I seem to remember that where they didn't want the surface cased, they used a layer of some kind of fire clay to protect the area, though memory does play tricks over the years!!

Bob.

[simplyloco]

Oct 5, 2018 8:04:40 GMT 92220 said:

SNIP Parts were immersed in red hot cyanide baths, for up to 5 hours for the greater depths. Definitely not a process for the model engineer!!
SNIP

Bob.

Our Army base workshop usually had a blacksmith's forge running, so the work would be left in it overnight. Once, just for kicks, I cracked open a 2" x 3/4" bar that I had just cooked and hardened, and I could clearly see the close grained surface layer, about 1/16" thick IIRC, and almost diamond hard. It would have made a nice piece of armour plate!
John

[Jim Scott]

Bob

Its hard to beat the cyanide salt bath for case hardening low carbon steel. The molten salt provides the carbon and is in intimate contact with the steel, oxygen is totally excluded right through to the quench resulting in a very clean, dull grey appearance. The depth of case can be readily estimated from the length of immersion and 0.030" depth is easily obtainable. I seem to remember from my toolroom days (late 1960's) that various non-cyanide salts were also used for heating HSS and other tool steels during hardening, also for tempering. I imagine it will all be different now but a quick web search shows that there are still commercial outfits doing this type of work.

Its always difficult to estimate the effective depth of case hardening when using Kasenit or similar. However, on a polished and etched section this can be seen as a thin dark edge, the thickness of which would normally be measured by means of a travelling microscope. The actual hardness is usually measured at the surface but thin coatings (or in our case a thin hard case) require special techniques to provide meaningful results.

I can't remember what we used to blank off parts that didn't require case hardening, in my case it was usually through holes which were fitted with plugs. I can remember partially immersing spindles though, so as to harden only the end portion .

John

Although a bit crude the blacksmith's forge would certainly provide the temperature and time. I'm at a loss to think what parts I would want to put in it though - I'm imagining what it would do to your old tobacco tin...!

I can well believe that you would be able to clearly see the case hardened layer when sectioned.

Jim S

[simplyloco]

Oct 5, 2018 19:53:34 GMT Jim Scott said:

Bob

SNIP

John

Although a bit crude the blacksmith's forge would certainly provide the temperature and time. I'm at a loss to think what parts I would want to put in it though - I'm imagining what it would do to your old tobacco tin...! 

Jim S

Nothing crude about a forge under the watchful eye of a skilled blacksmith. I did only one month in the shop as an apprentice, but the knowledge gained was enough to enable me to make, case harden and grind to size a replacement tank track roller pin. The baccy tin was for private jobs...
John

[delaplume]

Hello Jim Scott}--- and thank you for the offer but I also have a Kasenit tin looking very much the same as yours lurking in the back of my workshop cupboard..............If you remember this thread started from a question by a friend of mine regarding the use of Fryolux paste in place of the more traditional case hardening compounds...........Hello Simplyloco}---- I'm puzzled as to why you had to make a track pin for a Tank ??..........I would have thought you'd obtain a new one from the stores ?? ...........or was that just an exercise for you as an Apprentice ??

[delaplume]

I've just had reason to do some shopping at EKP supplies and saw this}----- www.ekpsupplies.com/case-hardening-powder.html

As per the original reason for this thread has anyone had a go at case hardening using Fryolux or similar ??