smallfry, The cast iron tray, like a rectangular casserole deep dish should have a ledge surrounding the top of the inside wall. The outside wall should project up above this so that the cast iron lid can nest in and on that ledge/wall enclosure. You lute the lid with fire clay to seal the joint. The lid should have a ring cast into it so that you have a handle to pull on during the removal of the luting. If you do not like tong marks on the parts wire them up with nickel wires with loops in the end. Empty space between the plastered parts should be filled with material also. The monoxide gas given off the carburising material not facing the parts would simply be absorbed by the cast iron tray. If you are worried about warp do a 2 stage quench, the first in a medium held at 375-400 deg. F. and when the parts are at equilibrium with that temperature, withdraw and quench again in oil at the usual,
125 degree F temp. A stabilizing "tempering" back in the same 375 degree solution, is a good stunt ,too. Cast iron tray? Because it doesn't warp all over the place

Steve, webb-www.pacmet.com and E-Mail pacmet@pacmet.com

poseur. Much good on you!

I suppose that any material with carbon could be used for pack carburizing but the commercial stuff is much better since it contains things like barium carbonate which make it more efficient....As for tempering ,always temper immediately otherwise you risk cracking, which some have already discovered !! There are various techniques to minimize warping and cracking but of course if you don't know the type of steel it adds risk.

Does the color case and packhardening processes require the parts to stay at critical temp for many hours? I recall using packhardening for a deep case on 1018 but not for anything else. That was at a large, modern manufacturing plant with a full blown heat treat department.
Could the Dakotas and others, made from ally steels, have suffered severe grain growth? It seems to me that thin sections could be through hardened while packhardening, added to grain growth would leave you with some undesirable traits in the finished parts.
Thanks to the knowledgable folks that have contributed so much to this thread.

Yes, I use the powdered milk in pack hardening. I first used it only because I was low on bone meal and couldn't get any quickly. Whatever is used it is best that it be very finely granulated to minimize air pockets. For a container I make them up from stainless tubing (8x81/2"). The lid fits outside and inside and is flanged. I dont worry about a little leakage but there seems to be very little.
I don't mess with coloring as a rule so I carburize, then heat treat. For a real deep case I will cook the pieces at around 1800F for 6-8 hours. They then remain in the container to cool overnight and are heat treated in the morning. This refers to fairly large pieces. Regards, Bill.

systeme98,

I am not sure what to make of this statement;

Quote:

---

poseur. Much good on you!

---

I will take it in a positive light, unless you tell me otherwise.

I have found you statements to be well stated and accurate.

If you took my statements as negative, and unwanted, I apologize to you. I have a pet peeve about the BS that has been stated about cryo treatment and it's benefits on the steels I listed.

Poseur:

Sounded pretty positive, to me.

Jay you're right about grain growth , that's why I said there are other considerations.I would be a good idea to normalize before hardening.A bit of experimenting should be done to find out just how much case you get.

A blind man will jump in here and attempt to lead people with good to correctable eyesight.



The American Machinists Handbook (Colvin and Stanley, 11th ed. 1940, p. 1054) has a diagram of the sparks you observe when you grind various types of steel. There are differences in the spark color, amount of spark, and spark behavior (some steels give mostly straight-flying sparks; other steels give sparks that explode and give secondary sparks). Mild steel gives light straw colored sparks that mostly don't explode. High carbon steel gives white sparks that mostly explode and branch out.



I'll leave it to you all whether it's worth grinding on an old Mauser to find out what it's made of.



H. C.

HenryC470, I have the same spark test in my 8th edition of Fred Colvin's valuable tome. Kind of a problem though with Manganese type steels. Both Iron and Manganese occupy the same color spectrum to the point it is difficult to separate the two in the spark trail. There are clues as to why Mauser used the steel they selected which you can find by reading up on "Stress-Proof and Fatigue-Proof-particularly on the rolling process for making Stress-Proof,
and pondering on what you have read. You might recall from your school days the great danger involved when you raised your hand and asked a pertinant question...So, Henry, for your special homework assignment..........

How about older Mauser actions like the 1893 and 1896? Who has had heat treatments done these actions? I was thinking that I might have a 1893 action case hardened just to make sure it was a solid as it could be. Any thought??

Thanks

Damn I miss Tom!

If you start out with graph paper..put RC 20 in the lower L. corner, then move to RC30, then RC40..etc. When connecting the dots, will you end up with a straight ascending line? Or..is it more like a Richter scale?

Duane.
The Rockwell C scale is pretty close to linear.
Meaning a piece of steel that is 41RC is not ten times harder then a piece that is 40RC.

We always specified hardness in terms of the mark you want to hit plus or minus a couple of points so it has to be pretty linear. If you were off by two points on a lambda (Ratio) you'd be off by a mile. Five points is not that large of a swing and raking a file across a piece of steel you'd have a hard time telling the difference between 40 and 50 RC

2004 ??? isn't that steel hot yet ?
I've been here too long

kcstott: Thank you! I just purchased a tester...uses a cabide ball that "dents" the surface...with a microscope, you measure the diameter of the "dent"

PS...Everything in the shop now has tiny little "dents"

quote:

Originally posted by z1r:
Damn I miss Tom!

Me too. Hard to believe almost 4 years.

Duane, what have all the little craters shown? If I remember right you are on the "doesnt need it" side of the heat treat fence, has this changed or been supported?

Red

quote:

Originally posted by Duane Wiebe:
kcstott: Thank you! I just purchased a tester...uses a cabide ball that "dents" the surface...with a microscope, you measure the diameter of the "dent"

PS...Everything in the shop now has tiny little "dents"

You got a new toy you HAVE to play with it.

This is the first time I recall having seen this thread and I'd like to thank all the contributors. I think I've learned good stuff from it.

It leads me to more questions about cryo, though.

IF cryo can be used to extend the working life of hardened steels which suffer from impact stresses, has that got any implications for its use on hammer-forged barrels?

Are hammer forged barrels even "work-hardened" in a way which would be comparable to heat/quench hardening?

Metals can be work hardened to a degree but not nearly as much as heat treating a suitable steel.
In the old days iron and bronze blades were often work hardened on the edges and this is quite visible on those blades. You can still buy scythes and sickles that can be hardened that way.
I have no idea how cryo would work on hammer forged barrels .
It's been a long search for info on exactly what cryo does .I finally found some answers . But it was a struggle to get past the BS and Hype !!
I'll see if I can find something .

quote:

I have no idea how cryo would work on hammer forged barrels .

what I don't get about cyro is it is said to remove stress from the material, but wouldn't some form of stress be introduced when the weapon was fired?

From everything I can find Cryo is nearly all hype.

MAybe in a few years when we have better testing and data there will be better information but I have not been able to find a source that I trust to give an opinion on Cryo.

Cryo isn't all hype but most of it is. I've searched for a long time to find the exact mechanism of what it does.On knife forums occasionally a 'metallurgist' would appear ,even one on th ASM Cryo Committee who couldn't answer the question .Just a bunch of
excuses.I'm retired so I don't have all the resources I used to have .
To put it simply cryo [with suitable steel] will cause some minor changes in the crystal structure . That in turn will permit ,on tempering , the formation of a fine 'eta carbide' .Thats what gives the additional strength and hardness. ! Just plain metallurgy , no 'miracles'.Benefit on other metals I haven't had an explaination for.

Stress - stress is not necessarely bad .Yes each time a bullet goes down the barrel the there is a stress induced .But this is temporary .Stresses that are higher will be permanent but of course some good some bad.One of the mis-statements I saw while reading about hammer forged barrels was about hammered barrels tend to bend when heated during firing. That happens ONLY if the stresses are not concentric. Have you seen the old way of straightening barrels ? A fixture with a large wheeel just bends the barrel the other way till straight !! Not for me.
Ain't metallurgy wonderful !

quote:

Originally posted by Duane Wiebe:
kcstott: Thank you! I just purchased a tester...uses a cabide ball that "dents" the surface...with a microscope, you measure the diameter of the "dent"

PS...Everything in the shop now has tiny little "dents"

So that's how you do your stippling...

This topic has been around for awhile and now I see more talk about color case hardening. One of the requirements to get an AA Gunsmith degree at TSJC in 1963 was one full semister on Metalurgy. It was taught by Jim Wilson which worked for Ackley first. It was hard to understand then as it is now.

I have asked if anyone knows what the alloy of a Martini small action frame could be. We run tests on some of the receivers back in 1993 at TSJC. I believe that these actions are 4130 or 4140. I know that the breech bolts are color case harden. Color case hardening actions looks nice, but may not be too safe when you are using pressures above 55,000 lbs cartridges. I asks the question on reheat treatment on some of these guys welding on bridges or front scope bases to actions and having these reheat treated. My understanding is that the early Mausers were case harden, but what happens to the Mk X actions that are supposed to be made of a high alloy. No one answered in an early post on the subject.

Did you flunk that course ? It's spelled Metallurgy !
The WWII and earlier Mausers were carburized steel similar to 1020. Today almost all receivers are 4140 or 4130.This is the Chrome-moly steel.For any process like welding or case hardening you should know exactly what steels you have and how to heat treat them.
A good general rule would be to temper at 400 F after welding and perhaps case hardening too.

I know this is an old thread, but I have to ask something. Blanchard's has been mentioned several times herein as well as in Kuhnhaussen's Mauser book as a source for performing re-carburizing of 98 Mauser receivers and bolts. Has anyone among you actually had a Mauser rehardened and it turned out well, i.e., did not warp or crack? I sent a 1908 Brazilian receiver and bolt off to a Guild metalsmith to be surface ground and heat treated. It came back looking beautiful (though sans crest and markings and bead-blasted) but when I tried to have it barreled by a second metalsmith some time later, he told me the receiver was too warped to use.

I have recently been experimenting with metal-polishing techniques on this "Model 98 doorstop" and have determined that even the surface of the receiver ring is not straight. A new bench stone dragged across the ring's surface doesn't even touch in about a 1/2" wide strip 1/3 of the way back from the front. Someone please tell me mine was a fluke and that you have it done successfully all the time.

I've never used Blanchards but Tom Burgess developed his method with PacMet becasue he was dissatisfied with Blanchards. Bear in mind, that was many moons ago and their process may have been improved since.

However, what you describe sounds more like poor surface grinding or "crest scrubbing".

I would not expect the surface-grinding technique to be at fault given the reputation of the smith who did it, but even if true it would not explain the warping of the receiver elsewhere. I would just like to hear from someone who has had heat-treating done successfully.

Never used Blanchards, all mine have gone to PacMet. All came back with no issues.

quote:

Originally posted by Glen71:
I would not expect the surface-grinding technique to be at fault given the reputation of the smith who did it, but even if true it would not explain the warping of the receiver elsewhere. I would just like to hear from someone who has had heat-treating done successfully.

I've had heat treating done successfully, just not from Blanchards.

I don't doubt that other areas of the action may have warped. But waht you describe, on the front ring, is not uncommon when dealing with scrubbed receivers. Not knowing more I'll reserve futher comment.

Seems like PacMet is a better choice.

The receiver was mint (if not unissued) with its crest and all markings intact when it was sent off for sutface grinding. Since it came back with no markings, I've wondered if it was even the same receiver. Thanks for the input.

When the receieiver was surface ground, what did you expect would happen to the crest?

Jim

I thought it would be gone. I was responding to z1R's comment that the concave ring surface could have been from an improper job of removing the crest. The point being that the person who did the surface grinding removed the crest, not some South American armorer.