Omelet wrote:
> Dave Smith > wrote:
>
>> Some additives will make steel stronger, and some make it more brittle.
>> Even heat treating can alter the properties of steel. Heat a piece of
>> steel until it is cherry red and then immerse it water to cool it
>> quickly will make it more brittle. You can take a piece of steel bar and
>> it will bend when enough force is exerted on it. If you use that
>> heating and quenching process, that same steel will not bend. It will snap.
>
> Does not tempering like that to hardness make it brittle, but harder and
> hold a sharper edge too?

It works by the same principle as steel reinforced concrete which is
stronger per weight then either steel or concrete. There's a soft/tough
material (concrete). There's a hard/brittle material (steel). When
they are mixed the soft material tries to stretch to the hard material.
The hard material gets stressed and toughens. For a very simple example
consider a plastic bottle filled with water. The water pressure puts
the plastic under tension and makes it stronger.

Doing that with steel has a hard crystal type on the outside and a soft
crystal type on the inside. It's the same element but because there are
different crystal types it's not the same material in a strict material
sense.

Doing it with all steel and heat treatment it can seem like magic. But
steel reinforced concrete seemed like magic to me until I spent a
quarter in college grinding through the math in my statics and materials
course. Ye gods that was a miserable course. But now i understand why
tempered chocolate works because I understand why tempered steel works
because I understand why steel reinforced concrete works. All the same
principle.