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Speaking of Precision

Speaking of Precision is a knowledge preservation and thought leadership blog covering the precision machining industry, its materials and services. With over 36 years of hands on experience in steelmaking, manufacturing, quality, and management, Miles Free (Milo) Director of Industry Research and Technology at PMPA helps answer "How?" "With what?" and occasionally "Really?"

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Five Facts about Manganese in Steel

Posted October 01, 2010 9:10 AM by Milo

Carbon is a chemical element that is the primary hardening constituent in steel. Manganese is a chemical element that is present in all commercial steels, and contributes substantially to a steel's strength and hardness, but to a lesser extent than does carbon.

  1. The effectiveness of Manganese in increasing mechanical properties depends on and is proportional to the carbon content of the steel.
  2. Manganese also plays an important role in decreasing the critical cooling rate during hardening. This means that manganese helps to increase the steel's hardenability. It's effect on hardenability is greater than that of any of the other commonly used alloying elements.
  3. Manganese is also an active deoxidizer, and is less likely to segregate than other elements.
  4. Manganese improves machinability, by combining with sulfur to form an soft inclusion in the steel that promotes a steady built up edge and a place for the chip to break.
  5. Manganese improves yield at the steel mill by combining with the sulfur in the steel, minimizing the formation of iron pyrite (iron sulfide) which can cause the steel to crack and tear during high temperature rolling.

Manganese is an important constituent of today's steels.

Manganese ore like this comes from Turkey.

Now you know a few reasons why Mn (the abbreviation for Manganese) is the second element shown on the chemical analysis report (right after carbon).

It's That Important!

Mn Ore Photocredit.

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#1

Re: Five Facts about Manganese in Steel

10/02/2010 12:23 PM

Doesn't large amounts of manganese affect the cold-work properties of steel? Seems like I recall being told once that the bars in jail cells are very high in manganese to make it difficult to saw through them as the steel work-hardens so fast that the action of the saw blade hardens the steel in contact with the saw faster than the saw/file/etc. can cut it. same with tooth inserts for things like backhoe buckets and dragline buckets and dozer blades.

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#2
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Re: Five Facts about Manganese in Steel

10/02/2010 2:22 PM

Yes. You're exactly right. That's covered in item 1. I think they call that Hadfields steel. It workhardens like a son of a gun. The more they work it with a tool, the harder it gets. Probably 12% Mn.

So if any of our CR4 Members get stuck in jail, hopefully they'll have learned to attack the masonry, rather than the bars...

Milo

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#3

Re: Five Facts about Manganese in Steel

10/02/2010 2:56 PM

Really great information! Thankyou to Milo!

I would like to know if there is an estimate to predict necessary cooling velocity by Mn-percentage?

And: work hardening once wasted all available drills as we tried to drill some holes into a safe (ex US army sold by DRMO) to use it as massive base for a small bandsaw ontop. (Welding worked perfect).

The hardest carbide tipped drills were worn out after a few revolutions but with a good pocket knife the surface could be scratched easily.

RHABE

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#4
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Re: Five Facts about Manganese in Steel

10/03/2010 2:14 PM

For that, a magnesium lance is the tool to use, as long as you aren't worried about the contents.

I wonder if a water jet would cut it, I'm sure a plasma cutter or a laser would.

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Re: Five Facts about Manganese in Steel

10/03/2010 4:35 PM

I'm not sure that I know of any material that a water jet cannot cut, although in very thin sections one might have some fixturing/ workpiece movement problems...

Milo

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#6

Re: Five Facts about Manganese in Steel

10/08/2010 3:25 PM

Thanks to you Guys I am now free.

Signed

Ex Jail Hoodlum.

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#7
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Re: Five Facts about Manganese in Steel

10/08/2010 3:34 PM

Thanks for the inductive validation!

here's the syllogism:

Premise: Ex jail hoodlum is now free thanks to us guys

Premise: The truth will make you free according to ancient wisdom,

Conclusion: Therefore, us guys gave "TRUTH"

Enjoy your first cold Beer, Ex!

Milo

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