I've seen some discussion on this site concerning reheat treating Mauser-type actions. Can anyone explain "re-carbonizing" actions, or "carbon enhancement"? I gather this is different than reheating. Thanks.

I was taught that any “heat treament†of steel uses the “Thee-T’s.â€

1. The material is raised to certain TEMPERATURE

2. Kept there for a certain period of TIME

3. And the controlled removal of heat causes a TRANSFORMATION.

Fully heat treated steel is transformed throughout its entire depth by a lengthy and controlled heating and cooling process.

Carburization is a process that transforms (hardens) only the outer surface of the steel by introducing extra carbon to the heated steel. This is also sometimes called Case Hardening.

Some of the early Mausers were made of soft steel with very little carbon. Carbon is the element that make steel hard. No carbon and it doesn't matter what you do, it will not get hard. However you can case harden by adding carbon to the surfaces and if you're lucky get maybe .020 penatration. This is good for wear surfaces and locking lug surfaces, but deep inside you still have peanut butter.

Think Twinkies, hard on the outside, soft in the middle.
Steels like 8620, if properly heat treated, end up with a hard case and very tough core. But plain old low carbon steel can only be cased (Twinkied).

So, OMJ, would it be better to carbon-enhance the earlier Mausers, such as a 1909 Argentine, rather than to reheat, which might result in brittleness?

Call the folks over at pacific metalurgical.

http://www.pacmet.com/proc_caps.html

quote:

Originally posted by dfielder:
So, OMJ, would it be better to carbon-enhance the earlier Mausers, such as a 1909 Argentine, rather than to reheat, which might result in brittleness?

I'm not a metallurgist nor a gunsmith. I will not put any time into a piece of material unless I am positive of the alloy if it is to be heat-treated.
My guess is that on the old Mausers, the popular treatment insures a hard case on the outside. Great for wear resistance but I'll bet that you can still get setback with a quantity of high pressure rounds. Unless you can get a rather deep case, like .015 or more. Your heat-treat metallurgist is the person to question.

Dfielder….The process you are referring to is called carburization which is a method of heat treatment. The re part for your question is to re-do the process because it was done wrong the first time. I will answer your question but it may not apply exactly to what you want to do. Here I go…..steel is iron with less than 1% carbon added any more and it is not called steel. Generally, low carbon steel has .2% C, medium carbon steel has .4% C and high carbon steel has .8% carbon. The last 2 digits in the material designation is the carbon content, i.e. 8620 has .2% carbon. Carbon is added to iron (steel) to give the steel hardenability. More carbon = higher hardness after heat treatment. So your medium and high carbon steels will thru-harden (surface to core), usually during standard heat treatment (austenitize, quench & temper). High hardness = low toughness, you may want to say brittle. Low carbon steels are more suited for the process of carburization as you will have less problems with brittleness. The process of carburization is heating low carbon steel to around 1700 F in the presence of an atmosphere rich in carbon (1% carbon potential). Over Time, the carbon will diffuse into the surface of the steel part. The depth it goes into the steel depends on the length of Time, the temperature and the carbon potential. You can control this process to produce the depth of carbon you want. If you want 0.010†or 0.100†you can get it + or - .002â€. Generally, you do not want to carburize deeper than 30% of the parts thickness as the residual stresses will change from compressive (good) to tensile (bad). Once the part is carburized to the depth you want you quench (rapidly cool). Quenching is the transformation or hardening process. This produces a hard phase called martensite. What you end-up with is a part that has a surface that is very hard (low toughness, brittle) for good wear resistance and a core that is lower in hardness and tough. This can be the best of both worlds. You usually want to temper after quenching. Tempering reduces brittleness by relieving stresses and lowering the hardness to an acceptable level. Sometimes the transformation during the quench cycle is not total (incomplete) and deep-freezing or cryo-treating LN2 (also know as extending the quench) will fully transform the steel and “stabilize†the steel. If the carbon potential is lower than the carbon content of the steel you decarburize the surface producing a soft surface. This is usually considered to be an undesirable condition.

I scratched the surface of heat treatment, carburization and metallurgy for you hear. If any of these processes are not done properly you will produce scrap, sometimes it can be re-worked or re-heatreated, recarburized, etc. I hope this sheds some light on what you want to do. If you don’t know the grade of steel you are working with and the condition it is in you will be shooting in the dark heat treating it. It is not a simple issue.

“Posted 30 December 2005 02:58
Dfielder….. Here I go…..steel is iron with less than 1% carbon added any more and it is not called steel.“

What do you call D7 tool steel...D7 “something other than steel?†D7 has a carbon content of 2.30%.

Don't know how many he had analyzed, or where and when they were made, but Gen. Hatcher in his Notebook said that the bolt and receiver of a Gew 98 were made out of steel very similar to SAE 1035.

GEW 98 ? so how does one heat treat sae 1035 steel ? Thanks

I'd expect that they were treated much like the original '03 Springfield's "single heat treatment," being carburized by heating in pots of ground bone or charred leather at 1500 degrees F or so for 4 hours or thereabouts, quenched, and then "drawn" for a few minutes at a lower temperature in an oil bath. Hatcher's Notebook has pretty detailed info on the process as it was applied to the U.S. Springfields. He was the guy who figured out why the early Springfields were sometimes too brittle, from improper temperature control in the process. (The foundrymen relied on eyeballing the color to judge the temperature, and their perception was quite different on sunny and cloudy days.) Some of 'em had the steel "burned," which can't be fixed by re-treating. They tried.

The Germans being such meticulous record keepers, I'll bet someone's got the information on exactly how they did it, but I don't. But the way Springfield did it is likely pretty close to the general process, perhaps differing in detail. I've never heard of problems with brittle old Mausers, only about problems with them being too soft.

John Westrum (may he rest in peace) had a brochure that stated that his research led him to believe that most mausers were 1330 steel, and that those made by Mauser were made of a swedish steel that had more nickle in it.

One of the favorite ways that used to be used to reharden these mausers was the use of a Cyanide Salt Bath. However, Cyanide is quite poisonous and so that method isn't used much anymore.

dfielder... to heat treat 1035 you would heat to 1550F in an atmosphere having a carbon potential of .35%, hold for 1 hour and quench in 180F fast oil (6 to 10 second) and temper at about 400F or to get the hardness you are looking for, I would say 40 - 45 Rc.

Rick D7 is tool steel as you said. That is another animal very different from what we are discussing, alloy and plain carbon steels. Tool steels are a separate category and heat treated very differently. Usually when you talk steel you don't include tool materials. If you want to be the exception to the rule, that's fine but we can't discuss every aspect of metallurgy in one session. I'm generalizing.

D7 is not the only steel that has a carbon content above 1%.

Based on your statement that anything with a carbon content above 1% is not called steel I was just wondering what all these commonly used materials are called.

JohnnyB, OMJ, others, thanks for the great information. Reheat treating obviously is a very complicated undertaking and must be considered carefully. I've wondered if people wanting to reheat the old Mauser-style receivers with low-carbon steel might be deluding themselves about the advantage of simply hardening the actions. I've read that the early Mausers were left "soft" inside for a purpose -- so that they would stretch under extreme pressure and not go off like a grenade. I shoot a couple of 98s -- a 1912 Styer in .30-06 and a 1909 Argentine in 7-57, but I don't push either one very hard. They're my "woods" guns and top velocity is not a priority. Rather, I like their slickness and ease of cycling while still at my should. Thanks again. I'm glad I've found this site.

dfielder another problem you can get into re-heat treating is distortion. You may get the action hardened, but it will not be straight. Heat treating will cause some distortion, I would guess it will be excessive.

dfielder-

This very specific question might not be appropriate for an open forum.

There are many who, although not qualified, are eager to help.

What you need to do is seek out contact information for the few heat treating outfits that have experience with old Mausers. If that's what you're interested in.

It's a fair certainty that these folks have been doing this for a long time, and can more accurately tell you what you need to know.

flaco

When making positive statements about "Mausers"
keep in mind that experts argue if 15 million, or 50 million were made. That leaves a lot of room for variation. It is doubtful if all were made from the same steel.
Many had the locking surfaces pack hardened, with the rest of the receiver left soft. The hardness of these can't be measured externally.
You cannot heat treat steel unless you know it's composition.
Good luck!

jonnyB
It looks like you're pretty well versed in the heat treating world. I've got a carburizing question for you. On the M14 print they spec using 8620H steel and in the mandatory requirements they say

"The use of straight cyanide bath or gas process shall NOT be permitted."

Is this because the heat treating world has come a long way since the manufacture of the M14?

I remember reading a great post by system98 on this matter system98 heat treat post

Another post of his I cannot find recommends Pacmet to case harden a mauser. I think they use the gas process. I'm just curious why the M14 print specifically says NOT to use this method??????????????????????????????

gunmaker

quote:

I've read that the early Mausers were left "soft" inside for a purpose -- so that they would stretch under extreme pressure and not go off like a grenade.

Quite true! If the early Mausers were made of a material similar to that used for the low-numbered Sprinfields, and the Mausers were heat-treated the same way, why aren't there any cases of Mauser receivers being so brittle that they shatter like some of the early Springields did? I know of stretched Mauser receivers, but not shattered ones.

Now it is a fact that a number of top-of-the line custom rifles have been built using DWM M1909 Argentine Mauser actions. Some of these rifles are chambered for cartrdges that operate at higher pressures than the early 7.65X53mm round (.270 Win., .280 Rem., etc.). So how do they get away with this? Were these actions all "re-heat treated"? If so, by whom, and how did they know how to accomplish this with the steels used in those particular actions?

gunmaker...cyanide salt baths are still used today to do some heat treating, not very often and usually small heat treat facilities (experimental labs). My guess would be the the print is a military print and knowing them (the government) they get hell bent on prohibiting certain chemicals, etc. They don't like cadmium either. These are dangerous chemicals and they don't want to support there use is my guess. They might get "Bad press".

Seems like the term HEAT TREATING is used rather loosly. The way I understand it, HEAT TREATING changes the hardness of steel. Steel cannot be HEAT TREATED if the carbon content is too low. CARBURIZING adds carbon to the surface of the steel. Mild steel (mauser actions) need to be CARBURIZED "and then" HEAT TREATED. Am I correct?

For those who save their RIFLE magazines, there is a very good article concerning this very subject in the Number 77 (Sept.-Oct. 1981) issue.

quote:

Originally posted by hart:
Seems like the term HEAT TREATING is used rather loosly. The way I understand it, HEAT TREATING changes the hardness of steel. Steel cannot be HEAT TREATED if the carbon content is too low. CARBURIZING adds carbon to the surface of the steel. Mild steel (mauser actions) need to be CARBURIZED "and then" HEAT TREATED. Am I correct?

Actually any change to the grain structure of the chemical composition of the steel is considered heat treating. Annealing is heat treating.....Carburizing (adding carbon to the surface of steels) is heat treating. Drawing (tempering) is heat treating....

In fact one can induce carbon to the surface of steels very deep.....the carbon will penetrate about .010 in the first hour of 1550 deg F and will go about .005' every hour thereafter..

Almost all high end mausers are thusly heat treated by master smiths as they get way too much cash for their guns to get them back later for setback.....

Literally thousands of mausers have been converted to .25-06, .270, .30-06 and other such cartridges with no heat treating at all and without trouble.

Unfortunately the 1909 Argie is frequently sited as having setback.......and after one has it made into a 404 Jeff...it gets real hard to fix it.....

Mine is a 25-06 with no heat treating and I have no problems with it at all.

As a metallurgist I would always have a Mauser recarburized especially the war time ones. Make sure the heat treater has experience in doing receivers....Hart 'heat treating' is a term covering everything done to metal involving heat and even cryo....Steel is defined as an alloy of iron and carbon.There has to be a certain amount of carbon and alloying elements to be able to harden steel.

quote:

Originally posted by mete:
As a metallurgist I would always have a Mauser recarburized especially the war time ones. Make sure the heat treater has experience in doing receivers....Hart 'heat treating' is a term covering everything done to metal involving heat and even cryo....Steel is defined as an alloy of iron and carbon.There has to be a certain amount of carbon and alloying elements to be able to harden steel.

Doesn't there have to be some minimum amount of carbon in the metal to begin with for it to be steel?? Otherwise, it is still iron!

Please ! If you know where to have this heat treating done ? send names and addresses , Thanks

Steel is defined by an alloy of iron with steel.In practical terms steels start at about 0.1% carbon. To harden a plain carbon steel you need about 0.45% C .Carburizing grades of steel usually have 0.20 C....BTW cyanide treatment adds both carbon and nitrogen [ carbonitriding] and is used where you want a thin very hard surface....pacmet does have a good reputation for redoing Mauser.

quote:

Originally posted by concho:
Please ! If you know where to have this heat treating done ? send names and addresses , Thanks

Blanchards Steel Treating in Salt Lake City....search the net they're easy to find

Hello Folks

Great discussion. Could I divert us a little and ask what would be a recomended course of treatment (if any) for a Martini Action. Most were manufactured in the late 1870's to 1900, so what sort of steel they might be I don't know. They seem very soft.

In retreating the action I would be seeking to "harden" it a bit so that the barrel shank threads would not wear quickly as a take-down. Strength is not an issue for the calibres I have in mind (say 38-55 or 38-303)

I don't know of any heat treatment folks "experienced" in the firearms field down here in NZ so it would have to be specified accordingly.

Cheers - Foster

Thank you Gentleman for you help , I have several actions I have made to be heat treated , I have contacted a few heat treat plants here in south east PA but they won't work on them .

quote:

Originally posted by Tentman:
Hello Folks

Great discussion. Could I divert us a little and ask what would be a recomended course of treatment (if any) for a Martini Action. Most were manufactured in the late 1870's to 1900, so what sort of steel they might be I don't know. They seem very soft.

In retreating the action I would be seeking to "harden" it a bit so that the barrel shank threads would not wear quickly as a take-down. Strength is not an issue for the calibres I have in mind (say 38-55 or 38-303)

I don't know of any heat treatment folks "experienced" in the firearms field down here in NZ so it would have to be specified accordingly.

Cheers - Foster

Just a guess on my part now.....carburize .03 deep and harden and draw to 38-40 Rc

Correct Vapodog internal parts should be 42/44 RC

Tentman

For the purpose that you are trying to achieve I would not recommend heat treating your rifle.
If I wanted to preserve the life of the threads of the takedown feature I would recommend having your barrel shank and the threads in your receiver Hard Chromed.

James