Author Topic: Case Hardening Experiments Mod-Up  (Read 17721 times)

Offline vtsteam

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Case Hardening Experiments Mod-Up
« on: May 09, 2015, 10:47:11 AM »
For this Mod-Up the goal is to come up with useful case hardening materials and methods for the hobbyist workshop. A method that uses commonly available, safe materials that produce repeatable results, in a reasonable time, is the hoped for goal. Actual experimentation, and results, rather than theoretical arguments, opinion, and hearsay (of which there seems to be a great quantity online) are the purposes of this Mod-Up.

Anyone can join, but I hope that there will be contributions results (and pics if useful) of actually testing rather than just procedural theories. And for any experimenter no matter if those ideas don't work, or do work out, either result is equally welcome!  Thank you, thank you! :bow: :bow: :beer:

Since this is a Mod-up, to put some very slight urgency to the matter, this thread will be closed, June 9, 2015.

Finally one stong caution. Some of the commonly used commercial or DIY suggested ingredients, the ferri and ferro cyanides can under certain conditions of heat or acidity produce cyanide gas, which is deadly. Online discussions disagree on what those conditions are, just as online discussions seem to disagree on most points re. case hardening. I personally intend to steer clear of them in this Mod-Up. In fact the desired result is a usable case, using commony avaiable materials that are reasonably safe.

Anyone want to join me trying out smelly concoctions and setting them on fire for the greater good? Thanks in advance if you do!  :beer:



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lordedmond

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Re: Case Hardening Experiments Mod-Up
« Reply #1 on: May 09, 2015, 11:11:30 AM »
I have seen this method used but a now passed over model engineer but not used it as we do not have a coal fire

He used to wrap the part in question in old cotton rags seal them in a tin ( small parts in a Bruno baccy tin) put them in the fire before going to bed this gave them a long hot cook in the embers , these were retrieved next day befor his boss slung them of with the ashes, he then heated them up to red heat and quenched in water .

Now I think that this method gave a shallow case but as it was for the motion work on loco,s it was ok , his reason to harden them was it gave a fine finish when polished up and a small amount of corrosion resistance

If it's not the info you want then delete this post
My self I used a kasenite but dip the part in water then into the compound then heat to red and quench, a point often missed is that a heat up to red and a slow cool will soften the case ,but reheat and quench will restore it
Stuart

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #2 on: May 09, 2015, 11:40:58 AM »
Stuart, not a problem, that's good info to try if someone wants to.  :beer:

I've got a similar direction I'd like to try in conjunction with charcoal making. One of the oft-stated theories is that cabon monoxide, rather than just carbon itself is the causative agent in closed vessel case hardening. Some say that pure carbon in the form of charcoal is not very effective in comparison with hooves, horns, leather scraps, etc. My guess is that these (and perhaps rags) may pyrolise to carbon, and the pyrolisis itself is important.

During wood pyrolysis, lots of carbon monoxide is evolved. So I thought I'd try putting those two things, charcoal making and hardening case together to see what happens.

One of the interesting questions to me is just how much oxygen is needed to produce the (supposedly) necessary carbon monoxide. Is an absolutely sealed container with nearly pure carbon perhaps too poor in oxygen to produce enough carbon monoxide for a case? Or is the carbon monoxide not the right transfer agent -- perhaps something other in say hooves, or rags is responsible. Anyway, trying things out is the real way to solve these kinds of puzzles.

I also would like to try Andrew's sugar suggestion.
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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #3 on: May 09, 2015, 11:47:53 AM »
Crushed bone and charcoal has been used also historically for case hardening, packed in an iron box and left sometimes for days, in a furnace.
Andrew Mawson
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Offline NormanV

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Re: Case Hardening Experiments Mod-Up
« Reply #4 on: May 09, 2015, 11:58:49 AM »
I once read somewhere that they used to wrap it in leather inside a sealed metal box and then heated it to red heat.

Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #5 on: May 09, 2015, 12:20:44 PM »
I believe that practically any source of carbon will work, and the various additives are to speed up the absorption process. I've heard of all sorts of weird concoctions being used, but with the exception of the Kasenit look-a-likes, the thing in common is heating for a long time in a sealed atmosphere to minimise oxidation.
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #6 on: May 09, 2015, 12:43:48 PM »
These are some of the theories commonly presented. Anybody want to actually try out a paricular method? and check results?

The sugar version I'll try today. Doesn't mean someone else shouldn't do the same material, since it is almost guaranteed that different people will use different procedures, and I'm guessing those can produce different results....
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Offline Lew_Merrick_PE

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Re: Case Hardening Experiments Mod-Up
« Reply #7 on: May 09, 2015, 02:20:56 PM »
The method we used in the tool & die shop where I apprenticed was to pack the parts in a (terra-cotta) ceramic "bowl" (more like a fully-bottomed cylinder) using bone mean and molasses as the pack.  This was covered with a slightly larger "bowl" (ditto) that was set into a coke forge on "dull-red" heat and left for 10-12 hours of "soak."  We then let the container cool before disassembling it and removing the parts.  We then fired up the parts to a "medium-red" and quenched them (usually Puget Sound salt-water).

We got consistent .080/.060 inch casing this way.  I last did this in the late-1980's.

Offline Manxmodder

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Re: Case Hardening Experiments Mod-Up
« Reply #8 on: May 09, 2015, 02:25:27 PM »
I believe that practically any source of carbon will work, and the various additives are to speed up the absorption process. I've heard of all sorts of weird concoctions being used, but with the exception of the Kasenit look-a-likes, the thing in common is heating for a long time in a sealed atmosphere to minimise oxidation.

Agree with you, Andrew, any source of carbon will permeate into the steel. Once it is in there the steel  can be treated in the normal way the carbon steel is hardened.

When I was a little lad the local blacksmith/farrier used to gather up all the horse hoof trimmings whenever he shod a horse.

These and old leather pieces along with the item to be hardened were packed into metal boxes and sealed with fire clay. He then put the boxes in the forge and left them at bright red allowing the steel pieces to absorb a case of carbon. The longer the metal is in contact with the carbon at red heat the greater the depth of case carburising becomes.........OZ.

Edit to add: A mate who does a lot of gun smithing tells me that carburising parts using small leather pieces gives the component a mottled finish often seen on older gun parts.
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #9 on: May 09, 2015, 03:01:23 PM »
Okay back to experiments, which is what this Mod-Up is actually about....

I removed the scale from 5 pieces of 1/2" x 3/32" from a ten foot length of ordinary hot rolled steel. I added a beveled end as a pseudo cuting edge and labelled them C for Control, S for Sugar, A for Air, and 1 and 2 for other trials.

C would not be heated at all. 
S would be an attempt to case harden with sugar
A would be another control which was heat treated the same as S, but would not receive sugar.

Here's the setup. A MAPP torch, cup of granulated cane sugar, and a container of water to plunge the pieces into.

Please notice I am going to use controls and the same stock and method throughout. That is important to avoid jumping to conclusions from a trial of any material by itself. I personally think that the failure to do that is responsible for many errors of opinion on the Internet.

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #10 on: May 09, 2015, 03:10:59 PM »
The  first trial, done mainy out of curiosity was the sugar coated trial.

The strip of steel was heated to cherry red (my estimate) and plunged into the sugar. The sugar carmelized into a pool immediately, boiling off steam, and darkening quickly to near black. There was flame above the sugar for a short time. When the bubbling had settled down a bit and I judged the coating would stay on the metal, but before it hardened in the cup - about 30 sec. I removed it.

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #11 on: May 09, 2015, 03:13:21 PM »
Here's the coating:

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #12 on: May 09, 2015, 03:41:43 PM »
I then heated it to cherry red again and plunged it into the water. Result: the metal was hardened and I was able to scratch strip C with it. I was quite pleased! Gosh, sugar works to harden ordinary hot rolled steel !!!

So, next to test the control, I heated strip A (with no sugar) to cherry red and plunged that into the cold water. Result: that, too was hardened and I was able to scratch strip C with it. Well, so much for the first conclusion!

Well, which was harder S, or A?

Scratching them against eachother, it seemed that A would scratch S slightly but not the reverse. Well this was too much, I wanted to make sure, so I sharpened both on a fine stone to give clearer results, and repeated the same case hardening method with each to hopefully increase case depth, and give a better indication.

The result: A definitely scratched S, while S only removed discoloration, but did not scratch into A. And not only that, but clamping C (the unheated control) in a vise and using A as a chisel, I was easily able to cut right into the unhardened control piece. You can see the notch made above A in this photo, and also the deep scratches it made on S. 



I also found it possible for a file to remove a small amount of metal from S, but not at all from A.

Conclusion, simply heating and plunging these particular steel pieces into cold water makes a harder tool than using sugar does. If I had done this experiment without a control, I might have assumed sugar was responsible for case hardening this steel.

In fact it appears it may inhibit hardening.



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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #13 on: May 09, 2015, 04:23:36 PM »
As a followup experiment to determine whether possibly a carbeurizing flame in the MAPP gas torch somehow case hardened piece A, or whether the material was itself hardenable, I ground the cutting edge back on the grinder and repeated the scratch experiment on C and S. No change. So my conclusion is that this steel is hardened all the way through, and therefore a hardenable material.

It is interesting that the sugar treatment seems to have reduced the degree of hardness.
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Offline Bluechip

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Re: Case Hardening Experiments Mod-Up
« Reply #14 on: May 09, 2015, 05:07:27 PM »
[1] Please note I know nothing about the subject.

[2] If you had some carbonising material ie. sugar and applied a flame I see no reason for the carbon to go into the steel.  I would assume it would be CO2. in fairly short order.

Dave

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #15 on: May 09, 2015, 05:09:59 PM »
And as one more experiment today, I stripped the zinc coating off of a piece of 3/8" dia threaded rod, in hopes that it wasn't a hardenable material. I heated it to cherry red, plunged it and it would not scratch either A or S. Both those samples would cut into it. So not hard.

It did seem slightly harder than C, but not by much -- light scratches. The untreated end would not scratch C at all. So, let's call it very slightly hardenable.

I did the sugar procedure on it, and it reverted to the full soft state, not even scratching C. So again, using this sugar case hardening procedure is counterproductive.
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #16 on: May 09, 2015, 05:16:12 PM »
Might be true Dave. What is unexpected is that it actually seems to pull carbon out of the surface.

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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #17 on: May 09, 2015, 07:09:53 PM »
Well the POWS got through the wire - read Paul Brickhills book !
Andrew Mawson
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #18 on: May 09, 2015, 08:32:41 PM »
Andrew I didn't conjecture about different procedures and materials used by other people. That's the point. Small alterations in details sometimes can make big differences in results. I pointed out the importance of individual method to start with, and still encourage others to try with sugar, including you if you want. A test only takes a few minurtes to do.

Also I'm sure my own sample S will cut wire if made into a tool. It just wasn't the sugar that caused it to harden. And a better cutter could be made of A. I'd guess Mr. Brickhill loses no credence as a result. But I won't be using this particular method with sugar to case harden anything.

I have thought of giving sugar one more try at least, this time in a tool wrap to exclude oxygen. If that fails then I give up on it.
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #19 on: May 09, 2015, 09:24:58 PM »
One other thing I just thought of re. The Great Escape. When you plunge the hot steel into the sugar you get a great volume of very strong smelling white smoke, very identifiably sugar -- like burning marshmallows, and flames. Then reheating it to red heat burns off all the remaining carbon producing even more fumes.

If I were trying to escape notice in using sugar, I'd use a sealed container method, not an open one. I doubt they'd have considered using an open method at all, under those circumstances. I haven't read the book, so I can't say what was reported there, though.
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Offline SwarfnStuff

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Re: Case Hardening Experiments Mod-Up
« Reply #20 on: May 10, 2015, 02:00:01 AM »
For what it's worth,
     I recalled reading somewhere that case hardening could be done in old sump oil. Easy to get some from my mechanic friend then recalling that it was supposed to be the carbon in the oil I ground some charcoal in a pestle & mortar, tossed it into the oil and left it for a few days. I had made a pair of mini bottle jacks from some scrap steel and thought they were good candidates. So, heated them to as red as my propane torch would get them and dropped them into the old oil. No hardening evident after trying the scratch test but hey! they had a nice black finish that looked good. (Now, this black finish bit I recall from blacksmithing class in junior tech school.)

 After reading the earlier posts perhaps I should have re-heated and quenched??

    Also tried sugar on some scrap but apart from the sweet smell nada. This thread will be interesting to follow. John B   :proj:
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Offline SwarfnStuff

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Re: Case Hardening Experiments Mod-Up
« Reply #21 on: May 10, 2015, 02:17:57 AM »
Another thought VT, you were wondering about trying to combine charcoal making and hardening -  later in the post you also wondered if the charcoal may be too pure in carbon to exude the monoxide. My thinking would be to try the steel in with whatever wood you were going to carbonise in the not fully sealed container (just need to exclude air ingress but allow pressure to escape. End of safety reminder.  :coffee:) and there should be plenty of CO amongst the other fumes.
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Offline Eugene

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Re: Case Hardening Experiments Mod-Up
« Reply #22 on: May 10, 2015, 05:58:16 AM »
Steve,

What your experiment demonstrated was the effect of "flame hardening" rather than case hardening. If you heat a bit of medium carbon steel to cherry red and quench it, it will produce a hardening effect, wether or no you have an external carbon source such as sugar. The process takes a couple of minutes.

"Case hardening" was traditionally applied to low carbon steels where an external carbon source was provided in the form of charcoal, the classical usage being in gun making. The advantage in using the mild steel was that it could be filed, drilled, ground, and engraved in the soft easily worked state, and then hardened to give wear resistance afterwards. The process takes hours rather than minutes, to allow for absorption of the carbon into the surface layer, quite a slow business. I'd guess all your sugar did was to make it more difficult to judge the colour changes, there wouldn't be enough time for a significant degree of absorption.

I've only done case hardening to produce the traditional colouring effect that is seen on gun actions, and I used the old style method of placing the parts together with charcoal into an iron box which went into a home made (and distinctly dodgy :() muffle. Getting the colours right is a bit of an art and is typically surrounded by a "bodyguard of lies", but the hardening effect is quite easy to obtain, it's depth depending on the soak time.

I think you'll be fine with home made wood charcoal if it's reasonably graded in size; small enough to contact the parts but big enough to allow the oxygen from the air to be present in good quantities. The oxygen isn't used up as the process continues, it merely has to be present to begin with.

I have some printed work on this iron box method; if you like I could scan it and send it to you. Let me know. Brownells in the US supply materials for the colour case process and may well have some info online; worth a shot.

In the far off days when I was alive, we used to copper plate steel parts in selective areas prior to them being hardened. The coating acted as a barrier to the carbon and left those areas soft. Only The Gubbernmint could afford it!

Eug
« Last Edit: May 10, 2015, 08:03:55 AM by vtsteam »

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #23 on: May 10, 2015, 08:04:39 AM »
Quote
What your experiment demonstrated was the effect of "flame hardening" rather than case hardening. If you heat a bit of medium carbon steel to cherry red and quench it, it will produce a hardening effect, wether or no you have an external carbon source such as sugar. The process takes a couple of minutes.

Eugene, I would say that the experiment so far demonstrated conventional hardening on the first sample steel, since it contained enough carbon throughout to harden, using a conventional method. And no "flame" or case hardening of the second.

JohnB, exactly what I was intending to try. I've made charcoal through a number of different methods over the years. There are plenty of variables to play with.

Please anybody jump in here with your own experiments -- using whatever appeals to you. We have only my photographed experimental results so far. Somebody with an acet torch could do the soot and heat method,, oil method, etc. As I've said before, method is as important as ingredients -- small differences can produce different results for different people. That's the point of documenting what you try.
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #24 on: May 10, 2015, 11:01:17 AM »
Continuing with the last experiment with sugar, I cut a piece of .002" stainless steel tool wrap and sharpened the non-hardenable steel threaded rod:

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #25 on: May 10, 2015, 11:05:27 AM »
The piece was heated to cherry red, and then plunged and stirred in the sugar. Lots of smoke and flames, etc.as before. The piece was well coated when done:

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #26 on: May 10, 2015, 11:09:31 AM »
The piece was then rolled in tool wrap several tight turns, the end folded over, and the remainder wrapped again to the end:

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #27 on: May 10, 2015, 11:15:59 AM »
The whole was heated to bright cherry red and held there for three minutes. Then plunged in cold water. The sugar coating hd further carbonized, but it did not burn off as it would in air:

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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #28 on: May 10, 2015, 11:26:09 AM »
The test piece wouldn't scratch the piece C (unhardened control) in this state, so I reheated it to cherry red and plunged it again in cold water. It did after that scratch piece C, showing that it did case harden to some degree using sugar without air.



The X shaped marks are the scratches from the case hardened rod.

You can also see in this photo how deeply piece A cut into the Control piece in the earlier samples experiment -- it left the notch on the left side of the photo.

Testing the sugar case hardened threaded rod against hardened pieces A and S showed it wasn't as hard as either. Neither could be scratched with it.

That's an end to my sugar testing for now.
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Offline Lew_Merrick_PE

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Re: Case Hardening Experiments Mod-Up
« Reply #29 on: May 10, 2015, 12:24:05 PM »
VTSteam & All,

Have you ever tried to work a piece of LC steel that was flame cut?  During that (flame cut) process the carbon in the steel migrates from within the part to the cut edge/surface and becomes quite hard.  That can be one of the effects you are seeing.

Carburizing, on the other hand, is the migration of carbon from the pack into the part.  This process most readily occurs when the part is heated to (and held) slightly above the Curie Point (which is the temperature causes a change in the crystal structure of the iron/steel such that it is no longer significantly affected by magnetic fields).  [Samurai blacksmiths used this technique to make the high-carbon steel for laminating their blades.]  It is known as a Time-Temperature-Transformation in metallurgy texts.

Heat Treating steel (and some other metals) is two processes:  (1) Hardening, and (2) Tempering.  Case Hardening (LC) steel is also two processes:  (1) Carburizing, and (2) Hardening.  The difference is that in case hardening the two may be combined into a single operation.

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #30 on: May 10, 2015, 12:56:08 PM »
Yup aware of all that Lew.

re.
Quote
Have you ever tried to work a piece of LC steel that was flame cut?  During that (flame cut) process the carbon in the steel migrates from within the part to the cut edge/surface and becomes quite hard.  That can be one of the effects you are seeing.

This isn't flame cutting, and the steel is far from molten, so not analagous. Carburizng is what we're doing (when it actually occurs.)

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Offline PekkaNF

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Re: Case Hardening Experiments Mod-Up
« Reply #31 on: May 11, 2015, 02:32:42 AM »
VT! I really, really appreciate your systematic approach and methology on this one.

Pekka

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #32 on: May 11, 2015, 08:40:13 PM »
Thanks Pekka, i hope something useful will eventually come out of it.  :beer: Sorry sugar hasn't worked out (so far anyway). I'd really like a cheap and easy and repeateable case hardening method, and I think one will eventually happen. The retort/sealed vessel methods take a lot of time and fuel. I've got some ideas I haven't yet had time to try for simplifying that.
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Offline bertie_bassett

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Re: Case Hardening Experiments Mod-Up
« Reply #33 on: May 12, 2015, 01:49:21 AM »
Keep up the good work  :thumbup:

Im sure there must be an inexpensive and reliable solution.

 I wish I was able to contribute but don't have the equipment or time at the moment.
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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #34 on: May 12, 2015, 02:28:03 AM »
Certain steels are designated for case hardening presumably as they take a decent depth easily. I wonder what they contain to achieve that property?
Andrew Mawson
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Offline David Jupp

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Re: Case Hardening Experiments Mod-Up
« Reply #35 on: May 12, 2015, 03:12:28 AM »
The speed/depth of carburisation will be diffusion controlled (temperature & time), largely regardless of steel composition.

Steel chemistry may be modified with other elements to further increase hardenability, or to promote fine & uniform grain size in core (toughness, reduced distortion on quenching), or to improve machinability.  Typically larger or more highly stressed components will require higher alloy addition (and hence more expensive) steels.

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #36 on: May 12, 2015, 07:44:43 AM »
Naturally. my interest in making case hardening more easily do-able in the home workshop is aimed at non-specialty steels.
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Offline RobWilson

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Re: Case Hardening Experiments Mod-Up
« Reply #37 on: May 12, 2015, 11:58:25 AM »
Interesting Steve  :thumbup:


You say easy to get items/chemicals ,,,,,,,,,,,,,,,,,,,,can I use Ebay ?  as I am finding that getting hold of Prussiate of potash is easier than the"pith of a rams horn "  ,no listing for the latter  :Doh:



Rob



Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #38 on: May 12, 2015, 12:46:31 PM »
Rob you can use any source you want -- no rules here!
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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #39 on: May 12, 2015, 12:57:52 PM »
Interesting Steve  :thumbup:


You say easy to get items/chemicals ,,,,,,,,,,,,,,,,,,,,can I use Ebay ?  as I am finding that getting hold of Prussiate of potash is easier than the"pith of a rams horn "  ,no listing for the latter  :Doh:



Rob

You should have said Rob - I have two Rams Horns drying on a beam in the stable - you want the pith it's yours  :ddb:
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #40 on: May 12, 2015, 01:31:49 PM »
Potassium ferrocyanide (prussiate of potash) is one of the reported ingredients in Kasenit. Although the can of Kasenit I have contains dark gray contents, not light yellow, so I assume it is only a component of a mix, not the pure compound -- unless the formula had changed when I bought mine.

While described as non-poisonous in itself, (and even used as an anti-caking agent in food) it must be kept away from strong acids in order not to liberate deadly hydrocyannic acid. My concerns are in any experimental mix people may come up with using other unknown chemicals in combination and subjected to heat, forming acids or otherwise liberating HCN.

I would avoid using potassium ferrocyaanide as a mix with anything else unless you are absolutely certain of the chemical reactions that will occur at high temperatures.

As a precaution, also, I only case harden with Kasenit outdoors.
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Offline Manxmodder

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Re: Case Hardening Experiments Mod-Up
« Reply #41 on: May 12, 2015, 04:56:22 PM »
Interesting Steve  :thumbup:


You say easy to get items/chemicals ,,,,,,,,,,,,,,,,,,,,can I use Ebay ?  as I am finding that getting hold of Prussiate of potash is easier than the"pith of a rams horn "  ,no listing for the latter  :Doh:



Rob

You should have said Rob - I have two Rams Horns drying on a beam in the stable - you want the pith it's yours  :ddb:

 Rob doesn't seem the type that would take the pith out of anyone on these forums  :)

What I am going to try is tapping a thread into some different samples of hardwood blocks and screw in a piece of low carbon threaded rod. Seal them up in a tin from air and pop them into the wood stove to bake and see if the steel will take on a case of carbon......OZ.
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Re: Case Hardening Experiments Mod-Up
« Reply #42 on: May 12, 2015, 05:13:52 PM »
Cool, Oz, thank you!  :thumbup: :beer:
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Offline Will_D

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Re: Case Hardening Experiments Mod-Up
« Reply #43 on: May 12, 2015, 07:02:38 PM »
I agrree about the look of Kasenite. Mine looked like a mixture of black, grey and white stuff(and some might have been crystaline and some amorphous). Definitely no signs of a yellow crystals.

If you want to buy Yellow prussiate of soda (don't you love the old names: "Whats that gov.? Honest gov. there be no cyanides in here!)" just look for that well known food additive E535 which is Sodium Ferrocyanide. It is Food grade - just don't add strong acids as it will liberate HCN (Hydrogen Cyanide*)

However as it is used in a closed container that is heated to dull red in a furnace, forge, BBQ, or with massive propane torch I wouldn't worry about any HCN being produced


*Little known fact:
Hydrogen Cyanide is actually less toxic than Hydrogen Sulphide (Rotten Egg Gas)(H2S that every school lab made in the infamous Kipps Apparatus (H2SO4 and FeS).

Also H2S has the sneaky property that it smells like rotten eggs in minute concentrations but as the concentration rises to toxic levels the olfactory senses (Nose) shuts down and no longer smells it. This is why so many people are killed on farms by entering slurry pits and the like!
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Offline S. Heslop

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Re: Case Hardening Experiments Mod-Up
« Reply #44 on: May 12, 2015, 07:40:22 PM »
I've been thinking about doing a stupid experiment to see if sodium ferrocyanide releases hydrogen cyanide when hot (600°Cish) in the presence of water vapour. Can't find any of it for sale in the usual places though.

I did chemistry at university and it's amazing how much i've forgotten over the last year and a bit. I'd like to be brainy and try figure it out with maths but it's all gone. Either way I think it'd be doubtful, the iron-cyanide bond is very strong.

But it's all pointless if it's impossible to buy (in the UK at least. There's an ebay seller in the US with it). I'm probably on a watchlist now after searching for chemicals.

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #45 on: May 12, 2015, 07:50:43 PM »

However as it is used in a closed container that is heated to dull red in a furnace, forge, BBQ, or with massive propane torch I wouldn't worry about any HCN being produced

Actually, in the torch and plunge method (ala Kasenit) it is used in the open and in flame -- that was my concern re. mixing it with other home brew chemistry.

I think "torch and plunge" is far preferrable for a thin case to heated sealed packs, since it wastes very little product, uses little fuel, almost no prep work or equipment, and is very quick.

One step toward developing a torch and plunge case is i believe  creating a molten shell that keps out oxygen. For this, I was thinking of something like borax or sodium carbonate. (Interestingly sodium carbonate's fusion temperature is about 1650 F -- right at the temperature often specified for case hardening.)  But I wasn't considering these fluxes in conjunction with any of the cyanide compounds. I don't like chemistry experiments of this sort where I don't absolutely know the byproducts and effects. :zap:

Instead, I was thinking of some organic carbon source in powder form with either or both of the fluxes. Preferably one with a little nitrogen as well (protein) -- might get a little organic CN action in there after alll. I'm thinking sanded hard leather scraps (powder), since it's traditional in sealed pack hardening. Maybe a rawhide chew toy for dogs.  Don't know if it's ever been tried in a torch and plunge formula. The smell should be interesting!

Might be interesting to try almonds or apple seeds in a case pack too if ferrocyanide compounds are unavailable for that!  :)



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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #46 on: May 13, 2015, 02:42:04 AM »
Steve try laurel leaves. There is enough cyanide in them to kill sheep that graze on them, as I know to my cost :(
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Re: Case Hardening Experiments Mod-Up
« Reply #47 on: May 13, 2015, 08:43:43 AM »
Andrew, thanks  -- I'm not sure what laurel, there, is... Here we have all kinds of things called laurel, depending on where you live in the country, or what you've planted as an ornamental. Have you got a genus name for  the kind you have?

Re. cyanide containing pure compounds here. The discussion is making me uncomfortable, since my hope was finding safe and readily available ingredients and methods for case hardening as alternatives to those compounds. I think it may be possible to do that, and I hope, with reductions in the need for prolonged high temperatures in a traditional pack case hardening method. It would be nice to have a method which provides a thin case for hardening taps and cutters for occasional use that took a half hour or less, and didn't consume large amounts of fuel in the process. Or require a specialty oven.

That's my hope. I can't stop people from pursuing cyanide chemistry for case hardening, but I hope great care is taken, and the risks are not minimized here in this thread (ie. is cyanide gas more or less dangerous than hydrogen sulfide). And people realize that at elevated temperatures and in combination with other compounds, a little bit of knowledge here is NOT sufficient. Further, as has been mentioned, there may be restrictions on commercial availability now for legitimate reasons.

That is why I started his thread - to find a useful alternative to all of these potential issues. The experimentation I hoped for, and hope to do, is in trying alternatives.
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Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #48 on: May 13, 2015, 11:18:17 AM »
Prunus Lusitanica or Cherry Laurel I believe


http://en.wikipedia.org/wiki/Prunus_lusitanica

Yew is another common tree that contains poisonous amounts of cyanide compounds

http://www.thepoisongarden.co.uk/atoz/taxus_baccata.htm
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Re: Case Hardening Experiments Mod-Up
« Reply #49 on: May 13, 2015, 06:27:24 PM »
We don't have that, Andrew, but we do have a lot of wild black cherry trees growing on our land, which could be tried. I think though that if I did, I'd only want to try that in a sealed pack, again, even though "natural".
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Offline Will_D

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Re: Case Hardening Experiments Mod-Up
« Reply #50 on: May 17, 2015, 06:25:05 AM »
Has anyone still got Kasenit?

If so could they to a photo of it?

BTW; Some suppliers on Alibaba search  may sell E535 in small quatities. If not try a lab supplier.
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Offline krv3000

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Re: Case Hardening Experiments Mod-Up
« Reply #51 on: May 17, 2015, 05:55:18 PM »
hi I have a tin in watt way do you mean tack a pick of it ie the tin or the contence 

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Re: Case Hardening Experiments Mod-Up
« Reply #52 on: May 23, 2015, 05:11:23 PM »
hi I have a tin in watt way do you mean tack a pick of it ie the tin or the contence
Its the the contents we are interested in. Is it yellow or black/grey/whilte speckled?

IIRC the tin is bright yellow
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #53 on: May 23, 2015, 05:13:50 PM »
Mine is grey.



edit:

Attached are MSDS for Kasenit and two other commercial case hardening compounds.
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Re: Case Hardening Experiments Mod-Up
« Reply #54 on: May 23, 2015, 05:35:47 PM »
Very inconsistent, re. that MSDS and the actual product -- also in the MSDS itself it is listed as the "potassium" salt, but the formula listed in the MSDS is Na (sodium).  :doh:

Like I said, all this stuff is too iffy for me to feel comfortable experimenting with those ingredients.

My next case experiment will probably be charcoal and sodium carbonate in a pack for an hour. And I might try wild cherry branches or leaves.
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Offline SwarfnStuff

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Re: Case Hardening Experiments Mod-Up
« Reply #55 on: May 23, 2015, 10:09:09 PM »
Hi all, I know we are looking for a cheap use at home method but has anyone tried this,
 "Cherry Red DIY surface harding powder. 400gm/14 ounces"?
  I came across it searching Ebay for "Case Hardening".
Don't add "powder" to the search string or you get lead into all sorts of guff.  :Doh:
Converting good metal into swarf sometimes ending up with something useful. ;-)

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Re: Case Hardening Experiments Mod-Up
« Reply #56 on: May 23, 2015, 11:19:06 PM »
I haven't tried it, Swarf, but it is the third of the MSDS pdfs I attached above.
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Offline tom osselton

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Re: Case Hardening Experiments Mod-Up
« Reply #57 on: May 24, 2015, 02:13:32 AM »
Came across this by powderkeg.
http://madmodder.net/index.php?topic=4603.0

Here is one that is also good and talks about how to harden specific parts of the piece.
http://bbs.homeshopmachinist.net/threads/59717-Case-hardening-success

Offline SwarfnStuff

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Re: Case Hardening Experiments Mod-Up
« Reply #58 on: May 24, 2015, 03:44:31 AM »
Thanks Steam, I admit to not looking at the MSDS pdf's as I am not intending to do any hardening soon. Interesting though to look now, as the product is sold as, "non toxic". MSDS starts with warnings that it causes irritation to Eyes, Lungs, Skin, and gut.    Fair enough to take safety precautions with any chemical anyway. Being in the textile dyeing game many years ago, chemicals were handled with gay (the old definition  :lol:) abandon in my day - now we or should I say "I"  know better hopefully. My son is into woodwork and I am impressed with him talking to his children whenever they come into the workshop about the No 1 rule "Be Safe".
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Offline Will_D

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Re: Case Hardening Experiments Mod-Up
« Reply #59 on: May 24, 2015, 05:18:15 AM »
Mine is grey.
Thats exactly as I remeber it.

It is obviuosly a mixture of things there are white crystals and at least on black powder. There seems to be no yellow at all.

The MSDS sheet is very misleading as it only list the potassium Ferrrocyanide and gives the (incorrect) formula for the Sodium salt (they ignore the nitrogen atoms attatched to the carbon [the cyanide group!!])

Reading through my machinery handbook they give a few recipes that use Cynaide for colour case hardenning (usually the Potasium Salt). They also state that if the colours are too rich leave out the cyanide!

So will WE!

I think then you should try a 50/50 mix of
Bonemeal Fertiliser (from a garden centre)
Crushed wood charcoal.
Maybe if you have some Borax (used as basis of silver soldering fluxes) add about 10% of that. This should glassify and help the powders to stick to the metal

You need to pack the metal and the above mix into a loosley sealed box, or better (they say) into a piece of iron pipe closed at one end. Put all into fire at dull red heat for several hours. Case hardening is a slow process. At end take out and quench in water!
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Offline bertie_bassett

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Re: Case Hardening Experiments Mod-Up
« Reply #60 on: May 24, 2015, 06:33:09 AM »
. Interesting though to look now, as the product is sold as, "non toxic". MSDS starts with warnings that it causes irritation to Eyes, Lungs, Skin, and gut. 

you'd be surprised at what not classed as toxic, recently did a chemical handling course and was informed that sodium hypochlorite solution isn't toxic, yet it takes less of it to kill you then chlorine gas!
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #61 on: May 24, 2015, 09:51:10 AM »
Came across this by powderkeg.
http://madmodder.net/index.php?topic=4603.0

Here is one that is also good and talks about how to harden specific parts of the piece.
http://bbs.homeshopmachinist.net/threads/59717-Case-hardening-success

Thanks Tom, both excellent! And somehow I had missed powderkeg's thread here. Too bad he never posted a hardening test.

The other thread is very informative, though kinda funny since it starts out with practical experimental demonstration of something, and then devolves into a bunch of experts posing theoretical arguments about what is "best" in their opinion. Meanwhile the results of the simple experiment and proof at the start that non-toxic ingredients work as well, in actual home shop conditions, using available ingredients and equipment is ignored.  One reason I like our own forum so well!  :) More doing, and showing, less theorizing.

Speaking of which, remember gentlemen, this thread is a challenge to throw your own iron into the fire and let us see the results!  :lol:
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Offline Manxmodder

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Re: Case Hardening Experiments Mod-Up
« Reply #62 on: May 24, 2015, 09:52:39 AM »
Had a look at the contents of my old tin of Kasenit yesterday and it has exactly the same appearance as Steve's tin.

Will get around to trying my threaded hardwood and sealed baking experiment in the next day or 2......OZ.
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #63 on: May 26, 2015, 10:06:51 PM »
Looking forward to it Oz!  :coffee: :beer:
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Offline jcs0001

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Re: Case Hardening Experiments Mod-Up
« Reply #64 on: July 14, 2015, 01:16:12 PM »
I wish I'd seen this thread a few weeks earlier as I had pitted a whole bunch of cherries and dried them.  The pits might be a worthwhile source of carbon however I'm not about to dig into my compost heap to try to recover them.

Will have to keep this in mind as we use a wood fire in the winter and it will give me things to do while trying to stay warm.

John.

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Re: Case Hardening Experiments Mod-Up
« Reply #65 on: August 01, 2015, 05:44:24 AM »
Can't locate here any Kasenit or such, but today in one local forum someone was sellig Potassium Ferrocyanide powder 5€/100g and remenbered this thread. Is this yellow powder as itself any good if I need to case harden small parts?

How are other experiments doing?

Pekka

Offline drmico60

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Re: Case Hardening Experiments Mod-Up
« Reply #66 on: August 01, 2015, 07:00:00 AM »
Hi Pekka,
If you mix the potassium ferrocyanide with powdered charcoal and sodium chloride (common salt) this will work in the same way as Kasenit. I think I used a mix with equal parts of each component and it worked OK.
I hope this helps
Mike

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Re: Case Hardening Experiments Mod-Up
« Reply #67 on: August 01, 2015, 11:27:29 AM »
I think you are missing the important variable in the sugar coated hardening experiment. Time.

All the anecdotes would indicate that the diffusion of carbon into the steel is not that rapid. Only heating for three minutes is probably not nearly enough time.
Mark

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Re: Case Hardening Experiments Mod-Up
« Reply #68 on: August 01, 2015, 06:40:07 PM »
Mark, I did what was claimed for a sugar case hardening method. Do you have a reference for the anecdotes you mention which specifically use sugar to case harden steel over a longer period?

I can tell you that diffusion of carbon into steel can happen considerably faster than 3 minutes.

It happens in seconds with Kasenit, for a thin case.


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Offline RotarySMP

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Re: Case Hardening Experiments Mod-Up
« Reply #69 on: August 03, 2015, 01:50:13 AM »
I was referring back to Andrew and Normans posts on page one.

Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #70 on: August 03, 2015, 09:34:29 AM »
Ahh, they were talking about pack hardening there.

The method previously mentioned for sugar was for a dip, heat, and plunge type and had its origins in a reference to "The Great Escape".

Dip types have the advantage for speed and convenience. And hoping to find a safe homebrew  alternative to Kasenit (a dip type) was the reason I started the thread.

As I mentioned, not many have access to long period high temp ovens, and even a woodstove isn't used in summer, so pack hardening is not very useful for most small jobs the way a rapid process like Kasenit is. Or was.....
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Offline Lew_Merrick_PE

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Re: Case Hardening Experiments Mod-Up
« Reply #71 on: August 03, 2015, 10:30:42 AM »
The method previously mentioned for sugar was for a dip, heat, and plunge type and had its origins in a reference to "The Great Escape".
Jerry Sage who escaped from Stalag Luft III was a member of my father's parish in Everett (Washington) when I was a child.  (1) The process described by Paul Brickhill was sufficient for the "soft" wire around many of the prison compounds, but not for the "hard" wire around cooler areas.  (2) Molasses or brown sugar were the "preferred" materials (but harder to get than white sugar) in Stalag's.  And (3) the person who started this "process" around the Stalag's had read about it in a WWI escaper story.

[And Steve McQueen did a horrible job of representing Jerry Sage and Al Hake in the movie!  Mr. Sage (who took a bunch of us to see it when it first came out) walked out after less than a half-hour into the showing.]

Offline awemawson

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Re: Case Hardening Experiments Mod-Up
« Reply #72 on: August 03, 2015, 10:33:37 AM »
There you are Steve - if not from the horses mouth at least from someone who mucked the horse out  :lol:
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Offline vtsteam

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Re: Case Hardening Experiments Mod-Up
« Reply #73 on: August 03, 2015, 02:21:10 PM »
Folks, sugar in air didn't work here to produce any hardening effect whatsoever. I wasn't trying to prove or disprove historical events. If someone wants to try molasses or brown sugar on soft wire in a test, I'm all for it! And if it does harden to a useful degree that would be great. Likewise if you want to try it in a pack, please do!

This was an invitation for others to help work out a useful quick hardening method. Nobody joined in, and the results are what they are. Don't like 'em? Do it better and write it up here!
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