Need advice regarding case hardening mild steel parts.

[Rolf]

I'm planning to case harden the sear, bridle and tumbler of the Alex Henry locks I've finished. These parts are all mild steel. Not looking for colors.
I have birch crushed charcoal, fine charcoal dust (floats everywhere in the air), bone charcoal and Beta casehardening compound (40% potassium ferro cyanide).
1. Suggestions for mixing ratios?
2. temp and soak times?
3. Quench in cold water?
4. The parts are mild steel. Should they be tempered the way as 1075 springs (370 Celius for 20minutes)?

Best regards
Rolf

[Bob Roller]

My case hardened parts were mostly double set triggers.My method was to heat the front and rear trigger together and they were hanging on a wire
and then covering them with Kasenit,a dark gray powder and heating them again and melting the powder and finally quenching them in heavily nitrated
water in a 5 gallon PLASTIC*bucket.Potassium nitrate will eventually cause a steel bucket to rust and leak and that is what happened to my steel bucket.
Kasenit is a now hard to find product here and the smoke is supposed to be toxic and does have a slight ammonia odor but nothing extreme.
   I have always used oil hardening steels for the sear,tumbler and fly and low carbon 1018 for bridles..The Kasenit will harden to a degree that seems to
last a long time.You may have a similar product in Norway and I am sorry about laws that make it hard to do anything we do here.Sending material from
the USA to Norway is costly now..I checked with our Post Office and the normal $10.20 to anywhere in the USA costs about$31 to send the same box to Canada.
Keep us posted about this fascinating 6 lock project.
Bob Roller
No tempering on case hardened parts needed because it is a surface hardening and not hard all the way through like a spring  or other carbon steel part.

[Blacksmoke]

Since it is hard, if not impossible, to find "Kasenit" anymore I found that a product called: "Cherry Red" works just as good and the procedures for case hardening are the same.   Hugh Toenjes

[Bob Roller]

Kasenit will give nice colors but it's a $#@* shoot for, I still have some from back in "The Day"whenever that was.I do remember low end gougers trying to sell a spoon
full for $25 at Friendship.I asked this guy if the absurd price would bring it back to the market again and got no answer.
Bob Roller

[45-110]

There is a source on Ebay selling what they say is the same formula as original Kasenite. It comes from Croatia. I would like to know if someone has tried it.

[Jim Kibler]

I would forget the Kasenite type surface hardening compounds.  These make a VERY thin hard shell as compared to a proper carburizing treatment.  To pack harden we use 2/3 hardwood charcoal and 1/3 bone charcoal.  We could probably use less bone and it would be fine.  The bone acts as an energizer that helps carbon diffusion and results in a deeper case.  We run lock parts at 1525-1550F and hold for 1.25-1.5 hrs at temperature.  We quench in more or less room temperature water.  Parts are then tempered at 525-550F for around 45 minutes.

[Bob Roller]

Jim Kibler's remark about thin case hardening reminded me of a comment by Chet Shoults many years ago.
He said it was so thin there is only one side to it.That IS thin.
Bob Roller

[44-henry]

The only thing I would add is that if your mixture actually is potassium cyanide than it is obviously quite toxic. Most of the carburizing formulas like Kasenit are actually potassium ferrocyanide which is considerably safer to work with. Wood and bone charcoal is what I use and is much easier and safer to work with.

[kutter]

potassium ferro cyanide is basicly non-toxic.
It is not the same dangerously toxic Potassium (Ferric)Cyanide compound of death chamber use.

Inspite of the potassium ferro cyanide similar name, it is used as a lot of things we come into contact with.
It's very common use is in powdered food mixes, it's used as as an anti caking/clumping agent.
Used in the Wine and Juice making industrys as well.

You can find old gunsmiths books reference it by the name of Yellow Prussiate of Potash or (Yellow Prussiate of Soda sometimes).
Used then just as Kasenite directions tell you to surface harden 'iron' or low carbon steel.

I think the 'Cyanide' part of the chemical name is what got it pulled from the market. Sounds scary.
In large quantitys it'd likely cause you harm,,as most anything will.
Don't eat dirt.

I have precious little of the stuff left. The Cherry Red powder works well as an alternative.
Easy to use The depth of case seems to be fine. It's just for wearability and thats just a part moving a few degrees in rotation in a lock.
Trigger parts case hardened with it seem to hold up just fine in my experience.
You can increase the depth of the case by increasing the time you allow the powder to melt into the surface. Reapplying it several times and keep heating it.
I've cased some very thin parts all the way through by mistake that just snapped in-two being brittle all the way through.

[Scota4570]

Kutter has that right.  Cyano is term for a kind of chemical structure.  It appears to me that the bureaucrats  who pulled Kasenite from the market were ignorant of basic high school chemistry.

[Blacksmoke]

What Kutter said!

[44-henry]

I agree with the last few comments, but in the first post Rolf made I believe he had originally listed it as potassium cyanide, not potassium ferrocyanide. That was the reason I responded to the post.

[kutter]

That does make a difference!

[davec2]

Potassium ferro cyanide is added to table salt to keep it from clumping......yes.....some pea wit bureaucrat made it illegal to sell because of the name.





Rolf,

More to the point of your post.....I think Jim K has it right but I have also had very good luck using an 18th century method of wrapping the parts in a leather thong and then wrapping the part in firing clay.  Let the clay dry and then toss the part in the fireplace coals for a couple of hours.  While still at a cherry red heat, I fish the part out of the coals and toss it in a bucket of room temp water.  I have never sectioned a part to determine the depth of the case, but then I've never worn one out yet either.  But because of the length of time at temperature surrounded by carbon, I would suspect that the case is fairly deep.  I read about it in some very old gunsmithing book and just wanted to try it.  Seemed to work fine.

Best and Merry Christmas

[Rolf]

Thank you all for your reply's.  Do you harden the lock screws along with the other parts, or do you only case harden the heads with kasenite or cherry red?

Best regards
Rolf

[P.W.Berkuta]

I have a few cans of the original Kasenite left and when I make my screws using 1018 mild steel I will case harden the heads and then temper them by doing a quick heat with a propane torch. Some say that this extra step is unnecessary, but I have case harden a #10-32 tang bolt without doing this and had the head snap off at the base of the head where the shaft starts . Your milage may vary.

[D. Taylor Sapergia]

I have a can of case hardening compound that was given to me by a millwright fellow who worked in a mill in a small community north of us.  It's called Hard and Tuff, and is a moss green powder.  To use, I heat the item bright red/orange in the flame of a torch, immerse the item in the powder and then hold it at that red heat for about two minutes.  I quench in room temperature water.  Then I dry the part, and burnish it in a fairly stiff wire wheel held in my drill press at highest speed.  The result is a tang or lock bolt that is a very dark grey, polished, and hard enough to withstand a ham-fisted client who removes them on a regular basis, without any damage at all.  I harden lock bridles and screws, including the wood screws for the buttplate, etc. with the same method.  the hardened screws resist oxidation as well as poorly fitting screw drivers.
I ran out of Kasinite many years ago.  Several years ago, I tried pack hardening using 50% hardwood charcoal, 25% bone meal charcoal, and 25% charcoal made from leather scraps.  The results of that were completely satisfying.  The colours were bright and varied, the steel could not be filed, and there was very little warpage.

[yulzari]

[Rolf]

I did a test run yesterday with rejected parts. Heated to 1550 for 1.5 hours. Parts packed in 80%wood charcoal + 10% bone charcoal (don't have much of this) + 10% Beta 1 hardening compound by volum. Harden in a bucket of cold water. Parts came out hard, no warping.

They have a greyish color. Can they be polish brigth again without removing the casing?
The screws seem to have hardend all the way throug. Is this okay or are they to brittel?

Will try annealing parts tomorrow.

Best regards
Rolf

[Adrie luke]

Hello Rolf

( I did a test run yesterday with rejected parts )

Place a part in a vice and hit it hard with a hammer.
If it breaks, it is too hard, then it needs to be tempered.
if you do the real work hard  do some extra old work and test this  the same

Adrie

[44-henry]

The surface oxides are easily removed in polishing. Your case depth probably is in the .003-.005 inch depth range, so polishing through the case layer isn't too likely at this stage. Small parts like screws with thinner cross sections are getting carbon penetration from all sides so they often achieve near total carbon penetration and will need to be tempered to avoid breakage.

This is a chart you may find useful in estimating case depth. Keep in mind it is only an estimate and involves compounds that are more efficient than wood charcoal with small quantities of energizers, but it does give you an idea about the time temperature effect on case depth.

[bluenoser]

I am by no means expert or even proficient at case hardening and have only case hardened on a couple of occasions with likely marginal results.  I don't question the estimated .003" - .005" case depth, but do question the chart.  The chart indicates a case depth of about .020" to .060" with a four hour soak, which sounds high.  Should that be .002" - .006"?

[Dphariss]

I'm planning to case harden the sear, bridle and tumbler of the Alex Henry locks I've finished. These parts are all mild steel. Not looking for colors.
I have birch crushed charcoal, fine charcoal dust (floats everywhere in the air), bone charcoal and Beta casehardening compound (40% potassium ferro cyanide).
1. Suggestions for mixing ratios?
2. temp and soak times?
3. Quench in cold water?
4. The parts are mild steel. Should they be tempered the way as 1075 springs (370 Celius for 20minutes)?

Best regards
Rolf

If you are doing charcoal you don’t need the chemical stuff.  Just case harden them and then draw them to 375 F so that edges do not chip. Like sear noses and tumbler notches.
They do not need to be further tempered if they are mild steel. In fact its not desirable. Casehardening will give a hard “slick” surface. Just be sure that the sear and notches are tuned before the final hardening. Good charcoal hardening done right, should give .004-.005” penetration. Room temp water is fine. More than this can cause issues with through hardening on thin sections. Not an expert in this but I know a guy that is.

[44-henry]

That chart has been around for awhile and I feel is accurate, but also is based on methods using different materials. On this forum we tend to focus on the more traditional materials and processes which, in this instance, don't compare in efficiency with what is used in modern industry.

I am by no means expert or even proficient at case hardening and have only case hardened on a couple of occasions with likely marginal results.  I don't question the estimated .003" - .005" case depth, but do question the chart.  The chart indicates a case depth of about .020" to .060" with a four hour soak, which sounds high.  Should that be .002" - .006"?

[bluenoser]

Thanks for the reply.
I think I will look into this a little more closely.  I find it difficult to believe one can achieve a 1/16" case depth with a four hour soak - using any method.  Then again, it would not be the first time I was mistaken.