Why do the old K98 rifles not rust as we know rust.

**Brenneke** · 12-05-2020, 00:24

Mauser Actions used a steel of Low carbon content, that approximates to SAE 1030-35. ( as do Arisakas as well)
There is NO "Heat treatment" as used with modern Alloy steels such as 4140 etc. The Finished receiver is "Case Hardened" ( Carburised) to increase the carbon content of the surface steels, in the high wear areas. The secret of the strength of Mauser (and more so Arisaka actions) is the bolt to receiver design, and the forging of the steel before machining to make sure "all the grains" are lined up, and the Case hardening ( usually only 1 or so millimetres depth) is for the wear resistance and impact resistance of such areas as Bolt locking shoulders, Receiver ring, etc.

BY WW I, the German Steel and Chemical industry had developed a more certain case Hardening process, based on a Chemical Salt bath, which was heated to carburising temperatures...This is the "Kasenit" process, using Potassium-Ferri-Cyanide to supply the carbon necessary for the carburization.

This shortened the carburisation process in Time, and made for a more controllable case hardness. This was used thru WW II on all Mauser Rifle receivers, by all makers in Europe. The Japanese used a similar system in the Arisaka production as well

https://www.practicalmachinist.com/v...-metal-228797/

(Now called nitriding )

Summary Technical Report of Division 18 NDRC
Volume 1
War Mettallurgy
Washington DC 1946

Perhaps this answers your questions ?

**treeman** · 12-05-2020, 19:20

This is what I wanted to know
The Finished receiver is "Case Hardened" ( Carburised) to increase the carbon content of the surface steels, in the high wear areas. The secret of the strength of Mauser (and more so Arisaka actions) is the bolt to receiver design, and the forging of the steel before machining to make sure "all the grains" are lined up, and the Case hardening ( usually only 1 or so millimetres depth)

And -
BY WW I, the German Steel and Chemical industry had developed a more certain case Hardening process, based on a Chemical Salt bath, which was heated to carburising temperatures...This is the "Kasenit" process, using Potassium-Ferri-Cyanide to supply the carbon necessary for the carburization.

This shortened the carburisation process in Time, and made for a more controllable case hardness.

I knew what I was seeing and I knew it was case hardening that I was admiring(or thought I knew)
Yes - now so much makes sense, now other metals and tools and thoughts fall into place.

Thank you for this info and key to answering some other questions.
It’s been about 18 years I been wanting to ask, get, find an answer, but the question always arises when I am far from PC.
Been on my mind years this matter. The salt bath thing I read about and realize now I know about some of this, just join the dots now.
I still think it’s the best steel I know.

Thank you

**treeman** · 12-05-2020, 19:25

The patina I was referring to - the salt bath affect. The hard glassed affect/ feel of the metal.
Tell you something else a very few will understand, it smells different.

**Brenneke** · 13-05-2020, 09:49

Originally Posted by treeman

The patina I was referring to - the salt bath affect.
The hard glassed affect/ feel of the metal.
Tell you something else a very few will understand, it smells different.

OK This is interesting

"Kassenite" refers to the additive / substance used as the material for the case hardening

Here is the recipe

Making KASSENITE the real thing

https://bbs.homeshopmachinist.net/fo...ing#post807414

https://www.polytechforum.com/modele...ing-28724-.htm

If you have a home workshop you can try this

You can also use this / some of these methods for COLOUR case hardening -- like on those very expensive custom British guns

LIQUID case hardening uses cyanide in a different form and these gases are toxic / dangerous

There are lots of different means / methods used for steel hardening / case / surface hardening

https://en.wikipedia.org/wiki/Case-hardening

https://en.wikipedia.org/wiki/Carburizing

https://en.wikipedia.org/wiki/Ferritic_nitrocarburizing

Carburizing:

https://www.brighthubengineering.com...carburization/

https://www.miheuprecision.com/blog/carburizing-101

What I quoted previously may not be completely accurate

"Hardening process, based on a Chemical Salt bath, which was heated to carburising temperatures...
This is the "Kasenit" process, using Potassium-Ferri-Cyanide"

These are TWO separate and different processes

1.) The liquid process

2.) The Kasserite process

NEVER take anything you find on the InterWebz at face value !

Kuhnhausen's manuals on double action Colt revolvers are so well written and have such good and complete content, that I think he must have been given the information by the Colt factory. Kuhnhausen's manual on Mausers content and style is so bad I don't think he wrote that either. I think it was an incomplete and unedited set of lecture notes from teaching a class, poorly. I think that R.A. Walsh's book, the only book by that retired chief engineer, was only written to right the wrong of the EXISTENCE of Kuhnhausen book on Mausers. I bought the Kuhnhausen Mauser book 13 years ago, and the damage has not ended. Right now my brother is lapping the lugs on a military Mauser he is converting to 270. At least he is not sending out out for heat treat.

https://thefiringline.com/forums/sho...=564740&page=2

For rifles NITRIDING may be a better approach ?

https://blog.metlabheattreat.com/pos...d-carburizing/

https://www.paulo.com/salt-bath-nitr...r-alternative/

From the UK

https://ukvarminting.com/topic/37647...rel-treatment/

NO idea if anyone in SA does any of this ? ( there is quite some detail and complexity involved )
I am sure it is used for other industrial processes
I am sure DENEL / used / uses something similar
However With out brain dead firearms laws you may not be allowed to send firearms parts to an company that does this for other segments of the engineering World ?

Perhaps some of our gunsmiths who possibly use some / any of these processes can enlighten us ?

**Brenneke** · 13-05-2020, 16:49

As promised -- an analysis of the metal used in the Mauser M98

From ...

"Mauser M98 & M96 How to build you favourite Custom Rifle"
R.A.Walsh
Pages .. 80 - 82

Mauser-M98-1.jpg

Mauser-M98-2.jpg