Advertised case hardening on BP revolvers

[64Springer]

How do you keep the hardening just on the surface then? Do you anneal the part after the quench?

The rapid cooling only effects the surface because the water is cooling the steel under the surface.

It's just a thin skin of really hard steel.

 

[Nav]

How hot does it run? I’m assuming you don’t go to red.

 

[64Springer]

How hot does it run? I’m assuming you don’t go to red.

Temp depends on the steel and the carbon present.

It's hot. Need heat to get the molecules in the steel dancing.

1,600 to 1,800 more or less.

 

[Jappo]

It scratches and it comes off. I accidentally got some Louisiana hot sauce on one and left a bare metal spot. This was a Pietta 1860

 

[64Springer]

It scratches and it comes off. I accidentally got some Louisiana hot sauce on one and left a bare metal spot. This was a Pietta 1860

That will happen with real case hardening too.

Case hardening colors are just oxidation.

Easily removed with acids and bluing remover.

 

[Jappo]

That will happen with real case hardening too.

Case hardening colors are just oxidation.

Easily removed with acids and bluing remover.

Ok, didn’t know that. Thanks

 

[Phil Coffins]

How hot does it run? I’m assuming you don’t go to red.

1375f to 1400f works on low carbon steel.

 

[maillemaker]

How do you keep the hardening just on the surface then? Do you anneal the part after the quench?

For an iron object, iron does not respond to heat treating/hardening. Only steel does. So by carburization, you allow carbon to migrate into the outer layers of the iron, which makes it steel. The steel will respond to heat treatment, while the iron core does not.

 

[denster]

The italians do not use the pack case hardening method they use molten cyanide as the carburizing agent. The colors come from the quench and for years the Italians used a rolling quench and the colors were light and streaky. In the last few years they have used a bubbled quench and are getting some pretty good work.

 

[Phil Coffins]

The cyanide case is used by many manufacturers to in include Shiloh (although they offer pack case as well). After annealed the modern made replica can be cased in the old style.
IMG_0400 by Oliver Sudden, on Flickr

 

[Blackpowderwarrior]

The cyanide case is used by many manufacturers to in include Shiloh (although they offer pack case as well). After annealed the modern made replica can be cased in the old style.
IMG_0400 by Oliver Sudden, on Flickr

Brother you gotta do a frame for me that's beautiful

 

[IanH]

For an iron object, iron does not respond to heat treating/hardening. Only steel does. So by carburization, you allow carbon to migrate into the outer layers of the iron, which makes it steel. The steel will respond to heat treatment, while the iron core does not.

To further explain, the term "case" means just that, a "case" or "encasement" of hardened steel on the very surface of an unhardenable iron part. Steel subjected to pack casing won't gain much if any carbon on the surface (depending on grade of steel) and will be nearly glass-hard all the way through when quenched from 1400 degrees F. It is unnecessary to anneal cased iron, except to control the surface hardness as required for certain metal-to-metal contact points which will gall if not slightly mis-matched in their hardness.

 

[M. De Land]

Both Pietta and Uberti have listed several of their BP revolvers as having case hardening and ask a higher retail price above the same blued model revolver. Question: Is this really true case hardened steel on the frame and hammer or just faux case hardening color effect using a chemical bath?

I can only speak to color case hardening with the old method of using bone and hardwood charcoal in various ratios to effect color and pattern. It is necessary in mild steel receivers to impart adequate strength by carbon infusion for the stresses it will encounter , the color and pattern are a pleasant side effect.but of secondary importance.
I make steel crucibles with loose fitting lids and pack the subject part inside and out with the charcoal mixture of bone and hardwood. The subject part is suspended in packed charcoal with at least a half inch between crucible wall and part. My best color and adequate carbon infusion (hardness depth) occurs at 1400-1425 F for 1.5 hours and then is air-eated distilled water quenched at room temperature. I draw the temper at about 500 F for another hour or so.
The color starts to get murky at much higher temperature than about 1425 F but the carbon infusion does go deeper with increased heat and time. Some of the shot gun and even rifle receivers are only heated to the 1350 F range yielding more spectacular color but very thin carbon infusion.

 

[nkbj]

It scratches and it comes off. I accidentally got some Louisiana hot sauce on one and left a bare metal spot. This was a Pietta 1860

Well, yeah, it's hot sauce!

 

[IanH]

You can go hotter/longer and then step it down a little for an hour before quenching to get better color AND deep case.

 

[M. De Land]

You can go hotter/longer and then step it down a little for an hour before quenching to get better color AND deep case.

I tried that but the color was still not very good and had to start all over again. Could be something other than heat, there are so many variables involved but that is what happened to my two stage heat treat attempts.

 

[IanH]

I've had them come out with lousy color and had to anneal and re-do them anyway, sometimes for the home-gamer it just doesn't work out the first time. I do think air-quenching and annealing after the deep carburizing and then starting over again to get the color is a better trick than just lowering the temperature for color but I don't have enough experience to say for sure, only did each method once, the first time I got decent color and the second time, second treatment after annealing got great color and depth. I was intrigued enough to consider using strictly cheap wood charcoal for the carburizing, then annealing the parts and going back in with my color bone/wood charcoal mix and aerated water quench.

Something I found out doing some restorations is that if the original case is deep enough, sometimes you can really bring the original case colors back with cold bluing.

 

[M. De Land]

I tried that but the color was still not very good and had to start all over again. Could be something other than heat, there are so many variables involved but that is what happened to my two stage heat treat attempts.

One successful technique I picked up from a British gun maker was to let the crucible rest for a full two minutes after removing from the oven before the quench. This of course is nothing more than then letting it cool down some before the quench but it did yield better color.
I don't particularly like British case colors as they are heavy in the browns and tans and very light in the reds,blue and purple generally.
I can also get brighter color if I polish finish the metal rather than my preferred glass bead "dull sheen" finish that knocks down the gawdyness of the bright colors. I think this look is more traditional than the Turnbull stuff !

 

[M. De Land]

I've had them come out with lousy color and had to anneal and re-do them anyway, sometimes for the home-gamer it just doesn't work out the first time. I do think air-quenching and annealing after the deep carburizing and then starting over again to get the color is a better trick than just lowering the temperature for color but I don't have enough experience to say for sure, only did each method once, the first time I got decent color and the second time, second treatment after annealing got great color and depth. I was intrigued enough to consider using strictly cheap wood charcoal for the carburizing, then annealing the parts and going back in with my color bone/wood charcoal mix and aerated water quench.

Something I found out doing some restorations is that if the original case is deep enough, sometimes you can really bring the original case colors back with cold bluing.

I ran out of hardwood charcoal one time and got the bright idea to try some coconut charcoal from a water treatment store and the dang stuff worked as well as the rather expensive hardwood charcoal. Might want to give it a try some time. I keep a 3x5 card record file of each evolution detailing all the particulars and results for a history of what was done.
Even a different steel type will yield huge difference in color and pattern all else being the same .

 

[#BPBReloadingFFL]

Brownells has a pdf instructor on case hardening.