[TheForge] Quenching mild steel - Hochewa ?

Wed Sep 3 19:18:01 2003

To All,
Do y'all know that I have a sister named Pandora?

You can form martensite with 1010 steel.  There is not a high percentage of 
it in the work and it isn't very hard.  

Martensite or super-cooled austenite can only form if you clear the pearlite 
nose on the TTT curve.  It is just the physics of the system.

The pearlite nose is at about 1200*F, more or less.  The more effective the 
quench is between the austentizing temperature and 1200*F the better the 
chances are that you will clear it.

Alloys tend to push the curve to the right.  More alloy, more time, slower 
quench, deeper the hardening.

Carbon has the single most potent effect on the hardness of martensite and 
the effect levels out about 0.6% carbon.  After that it adds more to wear 
resistance than hardness.

There are no reports in any journals to which I have access that describes a 
new phase that is the result of using "super-quench". 

The maximum allowable carbon in A-36 is about 0.35%.  Also 1.25% or so of 
manganese is allowed and manganese is a potent hardenability agent.  It is no 
small wonder that A-36 can be hardened if it is austenitized and quenched 
properly (or improperly).   4140 is pretty hard when fully hardened.  What differnce 
does 0.05% carbon make?

For plain carbon steels, A-36 included, it is ok to cool them any which way 
you please provided that you realize that you may have just hardened it enough 
that a blow from a hammer could crack it or that it may be a little hard on 
drill bits.  If you "quench" the work, take the time to reheat it before any 
other operations. 

For plain carbon steels, black is ok to be quenched in clean, fresh water 
without much happening.  For any tool steel that does not have a W in front of a 
number, water may not be a good choice.

Regards,

Hochewa

In a message dated 9/3/2003 12:31:16 PM Eastern Standard Time, 
[email protected] writes:
This is one for the "Rt. Rev. Hochewa of the Church of Orthodox Metallurgy"

"There is nothing SUPER or magic about "super quench" it is just a fast
quench made to be similar to quenching in a solution of NaOH without the
high risk to person of the caustic."  I for one, wish Rob had called it
something besides "super".  I am not saying it isn't a good quench media -- 
just that there is no magic -- it is just fast, like NaOH but much safer.

By the way are you asking about 1018 or A36 hot rolled?

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