doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Shooting Fox with annealed frame?

Based on differing research I would bet that the chrome/nickel/vandium steels used in the early 1900's were still low carbon content steels. Typically less than .3% carbon which still allows for case hardening, but likely increases the strength of the internal soft metal due to added alloying elements.

It would have been better to have the frame annealed prior to engraving and then case hardened. That would have been my recommendation.

Annealing resets the grain structure across the entire part during the cool down process. You don't get that during the heating phase of case hardening. So case hardening a second time without annealing may have a higher tendency to fail.

Here is another link to some general information on Chromium steels (41xx class) noting that there is 4118, 4120 and 4130 which can be case hardened. See description at bottom.

http://en.wikipedia.org/wiki/41xx_steel

From one website noting chromium being added to low carbon steels:

The development of 9�12% chromium steels is reported to have originated in 1912 with the manufacture of a 12% Cr 2�5% Mo steel for steam turbine blades by Krupp and Mannesmann in Germany. However, in 1912�13 Brearley in the U.K., while attempting to develop high-temperature steels for gun barrels, accidentally discovered that martensitic steels containing 13% Cr and 0.2% C did not rust; the stainless characteristics of high-chromium steels were also recognized by Haynes in the USA and by Strauss and Maurer in Germany at about the same time.

I have no doubt that the gun mfrs were playing with steel alloys in the first half of the century and earlier. I think they're still tinkering around with alloys.

As to whether or not "chromox" had carbon of sufficient quantity to harden, I suspect it did. I also suspect the "chromox" barrel steel wasn't used for frames. I welded LC Smith barrels from the 20's era and found that they hardened at the weld HAZ and weld bead from the 'self-quench' even though I used a mild steel rod.

Don,
Here's a link to a site that has some data on casehardened 8620. 8620 seems to have a big following for custom makers of singleshot rifles and possibly custom doubles that will get casehardened. Of particular interest to you may be the notation about the carburized casehardened thickness. They are quoting 1.9 mm.

"I suppose heat treatment is generally thought of as hardening, but I guess steel might be treated with heat for results other than hardening.

craigd, heat can also be used to anneal (soften until re-heat treated) heat treated steel alloys.

"I'm still not sure though what process or goal of 'heat treating' the core of a low carbon steel receiver would be."

There would be no purpose of heating the core of a low carbon receiver. It is "along for the ride" when the receiver is being carburized and hardened.

Thanks, Chuck. I'll have a look at these. I agree with you that Chromox probably was a low carbon steel alloy. Thus, it would have worked fine for barrels which were heated sufficiently for tinning in the ribs and ?brazing? for joining and the lumps (I don't remember Fox barrels as being chopper lumps - could be wrong about that one). I also agree that it would have added some strength to the action, whether cased or not.

DDA

You are correct Dick.



You are also correct Chuck.


Dick lays it out quite matter-of-factly and is entirely correct.


ALL of the Fox frames were cyanide cased (after about 1910 or so) and were cased by Fred Heinzelman & Sons in Carlstadt, N.J. for as long as Fox was in business.......Heinzelman & Sons is still in business today and is still doing guns (110 years or so) and could probably answer all your Fox receiver frame alloy questions for the data compilers here who are interested.

Cheers,

Don,
Here's the link

http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=M862AR

Doug,
Although I think the chromox barrel steel wasn't used for frames, it is very possible that the differences that our members have seen in the frame characteristics was a result of other alloying agents being added or changed during production years. My guess is that nickel was probably added along the way and gave that yellowish shiney look that was mentioned.

Chuck, I would agree with that thinking, although the cyanide colors from Heinzelman stayed quite consistent over the years which would indicate the alloy mix stayed pretty much the same for a long time........if anyone here wants a complete analysis, they should forward a sample of their steel to Kachina Metal Testing Laboratories in Phoenix.

Kachina will conclusively analyze the steel for anyone that wants to know, in as much detail as you are willing to pay for......their primary business is aircraft steel and alloys. Kachina is an established metal laboratory with years of experience and all the latest equipment.

I have used them many times over the years and the results were outstanding.

In one machine shop in which I put in betweeen 11 & 12 years 4130 & 4340 were our two main alloy steels. I would likely be utterly amazed if I had some way of knowing just how many pounds of each of these alloys I machined on & virtually all of it was subsequently heat treated. In all that time I never saw a part made of either case hardened. We normally did not case harden a part having a carbon content higher than 0.2%. 4130 we considered a water hardening steel & 4340 an oil hardening steel. Both of these alloys we heated in a neutral salt bath to hold down surface oxidation. Although we did not use near as much of it, we did occasionally use 4140 which due to the extra carbon over the 4130 was also oil quenched.

An interesting note on this website http://www.suppliersonline.com/propertypages/8620.asp
is that it indicates that 8620 will have a core strength of 135ksi after carburizing,quenching, and tempering at 250-300F. 135ksi core is pretty dang good for a casehardened part.