Adventures in case hardening part2

[RAT]

This is part 2 of my new adventures in color case hardening.

See (https://americanlongrifles.org/forum/index.php?topic=61673.0) for part 1.

This batch of parts included the lock plate, hammer, front & rear triggers, and bridal. The oven offered by Brownells allows you to program multiple “segments”. In this case I programed the oven to use 2 segments. The first segment heated the parts to 1400° with a hold time of 2 hours. The 2nd segment lowered the temperature to 1350° with a hold time of 1 hour.



I got a really odd pattern of color, especially on the lock plate. I wasn’t very happy with it, so I sanded the outside surface of the plate back down to shiny steel and put it back in the oven with some additional parts.

I’m pretty sure I know why this happened. When I packed the crucible I tamped down the charcoal around the parts with a wooden dowel. I think I used too much force and compacted the charcoal. I didn’t do that with the first batch of parts, and got much better results. The temperature and time were different, but I don’t think that was the cause. Please share your experience if you do this kind of color case hardening.

This was the result of the 2nd try on the plate. I’m a lot happier with it.



This batch of parts included the lock plate, hammer screw, barrel key inlays, and lock bolt washer.
I went back to my original program of 1350° with a hold time of 2 hours.

The next time I do a lock I think I’ll use 1350° with a longer hold time to increase the depth of hardness. I’m thinking of using 3-4 hours. The frizzen of a flint lock may need a higher temperature, I don’t know, I’m still trying to figure this out. Suggestions and comments are welcome.

[jerrywh]

I have case hardened for at least 50 years and I don't think your hold time is the problem in this case. I think you are correct when you say you tamped the charcoal too much The hold time mostly depends on the size of the case and the mass of the whole container.  I have seen one thing other that produces the type of colors that are shown on those parts. But that is not what you did.  I usually run up the temp to about 1500 and hold for 1 1/2hours, Then drop the temp t o1350 over a period of 1 hour.  But if you have a large heavy case it will take longer for the lower temp to stabilize. There is one problem that can occur if you hold the higher temp too long. The carbon can penetrate completely through the pieces resulting in part that is basically steel throughout.  I have had this happen but it takes hours. Less time on thin parts.  Be sure the parts are clean before packing.  just for an experiment I once powdered the parts with lime, The result was no color at all. One time I used powdered charcoal and the parts came out looking much like those you showed. spotted or speckled.  But every time is a surprise it seems. Are you aireating the quench?

[44-henry]

One thing that helps is keeping the charcoal mix in contact with the parts during the quench, parts that are blocked usually show dramatic colors on the underside where charcoal is trapped (assuming spacers are used) and wrapping the parts with iron wire, in part gives better colors for this reason. I used to use the Brownells crucible, but have long since moved to an inverted design. zi do this process a couple hundred times a year with students in my University lab and we color case harden hammer heads, engine parts, and other stuff. No gun work allowed at the university but I still get to do my experimentation with slightly different products. If you want to be bored you can read an article I recently published on the topic in the link below.

http://ijme.us/issues/spring2020/spring_2020.htm

[jerrywh]

 This is just my opinion but I think the reason for increased colors when parts are wrapped with wire or on the blocked side is because steam bubbles ware trapped there.  I believe it is the steam bubbles that cause the colors.
 That is why quench tanks are aerated. the bubbles cause more intense colors.  Not because the charcoal is trapped there. In one experiment I put a lock plate in a wire cage. The colors came out too intense. almost solid blue. 
44Henry.
   Thanks for the info. That is a super good article.

[Carl Young]

Alex, thanks for posting the link to your article! Good information there, as well as a useful reference section. I've saved a copy to my stash of gunsmithing info.

One suggestion from an academic who has been a journal editor and on many promotion committees, always try to cite your relevant previous work/articles in your papers. This will boost your impact factor  .

Best,
Carl
Carlton Young
Professor of Healthcare Administration & Law
Mississippi State University

[RAT]

Water was aerated for 15 minutes right before quenching, but stopped before dumping the crucible.

[44-henry]

When I was back in North Dakota we used to cool the quench water by dumping snow in the tank. This always seemed to provide better colors but whether it was the colder water or higher air concentration from the snow is hard to say. Also did the airline a bit at times, but when I first started doing this I followed Jerry's suggestion of using the wire which was more consistent.

I will throw a thank you out to Jerry on this. He is the one that really provided the information on this process that I and many others on this forum now regularly use. If it wasn't for his generous sharing of knowledge over the years I don't think many of these processes would be as prevalent as they are today.

[JCKelly]

Serious articles on this matter were written by Oscar L. Gaddy, The Color Casehardening of Firearms Winter 1996 and Spring 1997,  Double Gun Journal.
One hardens using bone charcoal, the colors being related to the tri-calcium phosphate present.
Quench in plain water. Lots of detail on just how it is done.
Read these. I have PDFs if anyone is willing to read them.

Jim Kelly, P.I.T.A. Metallurgist

[flatsguide]

Thank you for an interesting paper and also the replies. Is the anyway to Getz Oscar Gaddy’s two part arrival on CCH ?  JCKelly, I’d be interested in the PDF, thanks you.
 Cheers Richard

[flatsguide]

Spell check really messed up my previous reply. Does anyone have Oscar Geddy’s two part article on CCH and could PM them to me?
Thank you!
Richard

[Carl Young]

PM sent, hope the files come through OK.
Carl

[Daryl]

This is part 2 of my new adventures in color case hardening.

See (https://americanlongrifles.org/forum/index.php?topic=61673.0) for part 1.

This batch of parts included the lock plate, hammer, front & rear triggers, and bridal. The oven offered by Brownells allows you to program multiple “segments”. In this case I programed the oven to use 2 segments. The first segment heated the parts to 1400° with a hold time of 2 hours. The 2nd segment lowered the temperature to 1350° with a hold time of 1 hour.



I got a really odd pattern of color, especially on the lock plate. I wasn’t very happy with it, so I sanded the outside surface of the plate back down to shiny steel and put it back in the oven with some additional parts.

I have seen colour case hardening with mostly grey/brown, odd little blue spot on an original ALex Henry rifle.  I thought it looked rather subdued and nice, without the flashy 'stuff'.  It also
struck me as being more camo-effect.

[Clark Badgett]

This is part 2 of my new adventures in color case hardening.

See (https://americanlongrifles.org/forum/index.php?topic=61673.0) for part 1.

This batch of parts included the lock plate, hammer, front & rear triggers, and bridal. The oven offered by Brownells allows you to program multiple “segments”. In this case I programed the oven to use 2 segments. The first segment heated the parts to 1400° with a hold time of 2 hours. The 2nd segment lowered the temperature to 1350° with a hold time of 1 hour.



I got a really odd pattern of color, especially on the lock plate. I wasn’t very happy with it, so I sanded the outside surface of the plate back down to shiny steel and put it back in the oven with some additional parts.

I have seen colour case hardening with mostly grey/brown, odd little blue spot on an original ALex Henry rifle.  I thought it looked rather subdued and nice, without the flashy 'stuff'.  It also
struck me as being more camo-effect.

I like that look as well. Distinctive look.

[Daryl]

Yes, indeed.

[JCKelly]

Flatsguide I don't know what CCH is.

I'd be glad to send you an old-fashioned email if I knew how. Like, an address or how to find it

I presume there is a way obvious to all of you but damnfIno   I am not a computer guy, was born B.C.

[flinchrocket]

Just guessing CCH= color case hardening.