Heat treatment question

R

Ram4x4

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Jan 1, 2017
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I have a question that isn't necessarily about knives, but since knife makers are familiar with heat treating...

I have a 22 rifle (a Marlin model 60, to be exact), and it's not exactly pristine, so I am considering trying some things with it.

I don't know the exact steel the barrel is made of, but I suspect it is most likely 4140 as that is the most popular (I can find out though).

I would like to know if heating to around 575 degrees just long enough to get a nice peacock blue color then quenching it would ruin the temper? I know several gun makers (Cimarron Arms in particular) sells revolvers in this color and I want to duplicate that if possible.
 
I would recommend stripping it down and sanding the barrel/action it to the desired finish, then taking it to a gun shop to be hot blued. Heat bluing won't be very durable and may have adverse effects.
 
I understand hot bluing (I do it), but hot tank bluing is not the desired color. I also understand heat bluing isn't as durable, but not concerned with that either.

I just want to know what effects heating it to bright blue color will have on its temper. I understand that held at that temperature for extended periods absolutely will, but if it is done just long enough to achieve the color then cooled, will that kill the temper?
 
A salt pot filled with niter bluing salts would be the best way to get the desired deep blue at 575°F.
I did some gunsmith work a long time ago and couldn't recall a proper answer so I looed it up. 4140 barrels are quenched at 1550°F and then tempered at 1000°F. This would indicate you will do no real harm with a short coloring cycle in the range you want to use..
 
Great, thank you. Niter is what I was planning to do. It's popular for screws and other pieces on a lot of firearms, but I was curious about an entire barrel. I'm not sure of the process that Cimarron and Uberti Arms uses, but they do entire barrels, cylinders and sometimes the frames of some of their revolvers.

Here's an example with blue cylinder, barrel and a color case hardened frame:

pn7.jpg_thumbnail1.jpg
 
Usaly 4140 is tempered in the 1000° range to get the desired 35rc. When you buy 4240 quench and tempered steel that’s what it cones with is right around 1000° temper. But heating to get the blue might look good right out of the box but you can just about rub heat coloring off with your fingers. It’s very very thin and not resistant to wear at all. Hot bluing is very resistant to wear hence why it’s used in industry. Another option is to go old school and rust blue. It’s a very attractive finish that very durable. The only wAy you will get heat blue to hold up is if you never touch it and make it a wall hanger.
 
Yep, perfectly aware, I hot tank blue and have done rust bluing as well. This is specifically for being pretty, but I will shoot it some. I was more concerned with ruining the temper...don't want it to explode on me, but being a 22LR, I'm a bit less worried about that. I certainly wouldn't do this to a larger, much more powerful caliber.

I may have to research this more as those Uberti's don't seem to have wear issues, so need to find out how they're getting that color and have it durable.
 
I don't know how Uberti does it, but I know that a color scheme I see on custom single action revolvers is hot salt blue on barrel and cylinder, color case hardened on frame and hammer, and nitre blue on screws and pins and whatnot. (Take a look at some of the Bowen revolvers where they have Turnbull do the finish work.) I wonder if nitre blue is what you are looking for?

-Tyson
 
Yeah, I was planning to nitre the barrel, but that's more or less just a heat coloration too. The nitre salts allow even transfer of heat to the part (for more uniform color) vs trying to do it with a torch.
 
Go ahead and do it with niter salt. It will surely look pretty. It won't matter what the salt temp is as long as it stays in the salt coloring range of 570-650°F. After bluing and rinsing down, handle it with kid gloves ... literally!
 
Aha! I found it! Uberti, Cimarron Arms, and the others producing those bright peacock blue firearms use charcoal bluing. However, it too is just a heat bluing process and not particularly wear resistant.

Sigh...damn you mother nature and damn you physics and material properties science...

Ah well. I may just do it anyway. Like I said, it's not like this little Marlin 60 is a collector item or worth much, heck it doesn't even shoot that well. It's been a sort of experimental thing over the years. Did my first ever hand carved stock for it, so if it came out like crap I didn't really lose anything. Just something to tinker with (which I like to do).
 
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