[TheForge] carbon banding in 52100 steel

[David E. Smucker]

Was your steel from new 52100?  or from a roller bearing race?  If from new 
52100 stock then I don't have a clue, but if from a roller bearing race -- a 
Timken roller bearing race or even the roller then what you have is not 
52100 but deep case hardened steel.  The base steel is close to a 4120 but 
in the case the carbon content is raised to levels similar to 52100.  Not 
all roller bearings are case hardened, but all of Timken's are made this 
way.  Some other manufactures SKF, FAG, Torrington use a mixture of 52100 
and case hardening in "ROLLER" bearings.  As far as I know almost all BALL 
bearings are 52100.  The use of case hardening in the Timken Roller bearings 
is not to save money -- but to make a much better bearing.  Very tough core, 
with high hardness for the surface area to a depth of close to 1/16 inch. 
If you look at an etched section through a Timken race you can see the depth 
of the case hardening.

Dave Smucker
----- Original Message ----- 
From: "Lon Humphrey" <ironcrossforge at roadrunner.com>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Tuesday, May 08, 2007 9:55 AM
Subject: [TheForge] carbon banding in 52100 steel


> hi all,    ive just made a knife from 52100....i heat thermal cycled it 3 
> times and after the acid etch there is nice latteral banding visable 
> ....can somone explane to me what is going on with in the steel that makes 
> the bands show up.....ive searched this online and come up with nil
>
> i was under the impression that the only type of steel that you could get 
> the banding in was true damascus but i know Ed Fowler is getting this as 
> well
>
> Lon
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