How to do Color Case Hardening

Thanks for the compliments Frank and I'm glad you are enjoying the build. My thread on the Steven's Favorite is being hosted here on Hobby Machinist and over on MetalworkingFun. It's idle at the moment, because I've had to take time out to work on a paying project for a while, but I'll be getting back to the Favorite soon. The latest push has been getting set up to drill and rifle the barrel.

If you are looking to build a heat treat oven, I've recently discovered a digital control that is inexpensive and would work very well. All you would need is the control, a high temp type K thermocouple and a solid state relay to control the resistance element in the furnace. You can check out the control on this thread. Also, this guy goes into great detail about how to build a furnace built around a heating element for a kiln. You may want to purchase his book on the subject.

Tom
 
I've been researching what I need to make a smallish heat treat furnace and ordered most of the controll items off of one guy on ebay. The PID controller, the SSR and its heat sink and a high temp thermocouple. Still need to order the soft fire bricks, the heating element and the high temp hook-up wire for the element. Since I read the info in the link on the casting furnace that you supplied in the above post I may decide to use his recipe for the castable refractory used in that article rather than buy "Fiber Fax" insulating blanket. I still need to make a mock up of a prototype before I know how big this heat treat furnace will be. It will need to be big enough to hold a steel pot big enough for a number of small parts plus a receiver, and long enough for a decent sized knife blade.
By the way thanks for the "this guy" link!!!
God Bless, Frank.
 
Last edited:
The very best source of information on Colour Case Hardening can be found here :-http://www.marlin-collectors.com/forum/viewtopic.php?f=21&t=3732&sid=fff443322de44ac6480bdfe492c43a25
The thread runs to 30 pages and it takes a while to real all the pages and digest the information. Unlike many so called 'Experts' the writer actually shows his results and the methods of obtaining them. The two part article by Oscar Gaddy is interesting but very much out of date. There is far too much hocus pocus written about CC Hardening. Some of it makes Shakespeares Witches in Macbeth seem to be modern scientists. Just as an aside 'Wing of Bat and Eye of Newt seem to make the finish too green' lol.

Harry

I am just curious what would make you figure that the Gaddy articles are out of date? I have looked at images of color case hardened surfaces under electron microscopes and they appear, in most respects, exactly how Gaddy reported them to be. In addition, his study of the process was based on years of personal experimentation. The Marlin thread that you reference is not the only look at the process and there have been many others who have taken the time to detail the work that they do with plenty of detail for those who wish to re-create the results. I certainly hope that you are not grouping the rest of us as the "so called experts". Also, the gentleman who did all the work in the Marlin forum was not casehardening, he was coloring. His quench temperature was far too low to yield any substantial hardening and that is not a really good idea when working with something critical like a receiver. Anybody who has done any heat treatment would see the problems with his process. Just because his results looked pretty does not mean that his work stands as the definitive work on this subject.
 
Thanks for posting all of this information. I have been studying CCH and this thread has set me on the best paths. I will continue to research and acquire the pieces needed to do this. I am going to start on small pieces and make practice pieces and hopefully I will eventually be able to CCH. The first actual gun I want to do is the frame to my 1911. I am curious if anyone knows the size/shape of fixtures that I will need to make to prevent warpage. Right now, the only thing I KNOW is the pieces need to made of Stainless steel, as well as the crucible. Any information will help!

By the way, this tread is what got me to join the forum and I am loving what I am seeing everywhere else.

-Chris
 
Thanks for posting all of this information. I have been studying CCH and this thread has set me on the best paths. I will continue to research and acquire the pieces needed to do this. I am going to start on small pieces and make practice pieces and hopefully I will eventually be able to CCH. The first actual gun I want to do is the frame to my 1911. I am curious if anyone knows the size/shape of fixtures that I will need to make to prevent warpage. Right now, the only thing I KNOW is the pieces need to made of Stainless steel, as well as the crucible. Any information will help!

By the way, this tread is what got me to join the forum and I am loving what I am seeing everywhere else.

-Chris

Chris, before you start to CC Harden you should find out the type of steel used to make your 1911 frame. Only very low carbon content steels can be CC Hardened. Having worked on a great many .45 Colt semi-automatics I would be very wary of CC Hardening the frame as it is very thin in many places and there is a great chance of warping. Get in touch with the manufacturer of your pistol, (there were many), give the model and Serial No and see if they can tell you what specification steel was used in it's manufacture and how it was heat treated. The carbon content should be no more than 0.1%, if it is more than that, forget about it, you would be better off leaving it blued. Stainless steel is not necessary for a crucible, mild steel works just as well and is a lot cheaper. Don't forget that any steel that has been previously heat treated has to be annealed prior to CC Hardening. Harry.
 
Chris, before you start to CC Harden you should find out the type of steel used to make your 1911 frame. Only very low carbon content steels can be CC Hardened. Having worked on a great many .45 Colt semi-automatics I would be very wary of CC Hardening the frame as it is very thin in many places and there is a great chance of warping. Get in touch with the manufacturer of your pistol, (there were many), give the model and Serial No and see if they can tell you what specification steel was used in it's manufacture and how it was heat treated. The carbon content should be no more than 0.1%, if it is more than that, forget about it, you would be better off leaving it blued. Stainless steel is not necessary for a crucible, mild steel works just as well and is a lot cheaper. Don't forget that any steel that has been previously heat treated has to be annealed prior to CC Hardening. Harry.


I wouldn't be too quick to caseharden a 1911 frame. I do a lot of gunsmithing projects and I am well versed in the color casehardening process, but that is a job for a specialist like Turnbull Restorations. As Harry mentioned stainless steel is not required for crucibles, I probably go through a dozen or more a year of mild steel ones, but they are cheap and they work fine. Stainless is nice too if you have some, but not necessary.

On a side note, high carbon steels can be colored using the color case hardening process, it serves no real useful purpose other than putting the colors on the part, but it can be done. Following the operation they need to be tempered and as long as you don't go much beyond 450 degrees F you won't mess up the colors, in fact, I generally draw most of the parts that come out of my tank at 450 following the quench because I feel that it enhances the colors.

Regards,

Alex Johnson
 
44-Henry and Harry Eales,

Thank you for the information. I got my hands on a 6" by 8" Stainless tube, I will make the crucible out of. Just needing a base to weld onto it.
The plan is, trail and error the crap out of this process before doing it to my frame. My frame is a Norinco, so it is a fairly hardened steel in first place. I plan on making some supports through the magazine well, the grip safety/mainspring housing area, and the barrel support. All that to decrease the warping. Will probably make a support for the slide/frame meeting point, maybe not, though. That is an easy fix. It will be a while before I can do this, but I will update as I can.
 
I'm having trouble understanding the "wrapping with iron wire" part. Is it done is a loose wrap, or tightly, and is it supposed to completely cover the parts to be CCH?
 
Just finished reading Tubal Cain's Hardening, Tempering and Heat Treatment. Very interesting, and has a separate chapter for Casehardening
 
First off I'm as much in the dark about color case hardening as the most ignorant person on this site, which come to think of it could be me. I did see a YouTube video ( see link below) of Uberti's method of color case hardening. They boil the item (in this case the frame) in a salt compound, don't know what salts they are using, then quench it in water. This seems to be all they do to achieve the finish we all like so much.

Still don't understand it but perhaps someone here could enlighten me/us more on this method and if its practical for the hobby machinist.

http://www.youtube.com/watch?v=qYOJa8ZNxmE
 
Back
Top