Dan_the_DJ

Leaf spring making from mild steel?

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No reason to heat treat before adding the carbon..  Well unless you want to anneal it only then case harden it.. Then harden it.. 

     So,  the case hardening will only penetrate so far.. The outermost area will have the highest carbon content equally distributed around the object depending on contact with the carbon and metal.. This outer skin is the carbon rich metal..  which I know you know..  The surface of the metal will have a mottled appearance.. 

If you do it correctly and do a really deep case hardening the problem is the outer skin will be very high in carbon and the inner core will be less to none..  In a knife you want a nice finish..  the mottled look isn't a big seller today.. :) 

Case hardening is desirable for a product that needs to be tough but wear resistant.. .    Look up Japanese blade construction,    hard skin soft core..  This allows for a very hard edge with a softer more ductile inner core for strength.. 

Done well and done right it will in fact make a wonderful knife..  but it is a bunch of work that offers little advantage other than the fact of saying you did it..   I had many projects like these myself when I was very young. 

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You missunderstood me in the begining, I wanted to say that I would go about making the knife as you would a regular 1085 knife, with the exception that prior to HT, I would do the case hardening of the blade blank.

Only after that would I attempt any kind of quenching and tempering, there is no point before the carbon is tucked in there :D

But thank you very much, you have pretty much answered my question...

My main problem will be uneven distribution of carbon. Is there a way to fix that?

Maybe, heating the piece in an inert atmosphere to allow the carbon to difuse along the piece more evenly and without adding even more of the carbon to the surface layers, hence the inert atmosphere?

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What about Grain Growth?  Larger grains make for a weaker blade.

In general I would advise spending the time finding a car or truck, coil of leaf spring and using it rather than trying to force a blade out of an inappropriate alloy.

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Well if you want to read up on it...."The Cementation of Iron and Steel" Federico Giolitti; is a great resource  How it was done commercially is covered in "Steelmaking before Bessemer, Vol 1 blister steel, Vol 2 Crucible steel"  Kenneth Charles Barraclough

Note is is possible to over do it, I've turned some wrought iron essentially into cast iron, it fell apart when I tried to forge it after carburizing---and I had forged it prior to carburizing with no problem...)

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