On 22/06/2010 2:42 AM, Omelet wrote:
> In m.au>,
> > wrote:
>
>> Even in the narrow range of concentrations which make up steel, mixtures
>> of carbon and iron can form a number of different structures, with very
>> different properties. Understanding such properties is essential to
>> making quality steel.
>
> So how do you feel about recycled steel?
> Tons of dead cars go over to other countries ever year to become more
> cars.
>
> I've heard bad things about engine blocks made from it.

contaminants - see below
>
> Is it simply a matter of forging temperatures?
>
> I'm very much a believer in recycling whenever and wherever possible...

Recycling steel is a wonderful concept. The problems arise because of
the vast range of impurities in the recycled material. Even running the
recycled steel through the smelting process doesn't guarantee that the
iron or steel output has the correct alloying makeup. Probably this
arises because of the exotic contaminants that are in the recycled steel
as opposed to raw iron ore dug up from the ground.

Many years back, when we were running a desert rally in the Pilbara
region of Western Australia, I took the opportunity to visit and do
tours of the iron ore mining and port facilities. I was amazed at the
purity of the iron ore they were digging up, anything up to 90%. Much of
the ore was too pure for the smelters in Japan so one of the functions
of the loading process at the port was to grade the ore into the desired
purity level by blending high and low grade ores. The smelter operators
knew exactly what impurities were present and could gear the processes
up to deal with it.

If you get an opportunity, go visit a car recycling plant and see just
how cars are recycled. They aren't stripped into their component parts
and graded into various levels of steel. Instead the entire care is
shredded or just simply crushed into a block. Contaminants include glass
and plastics, not good inputs into the steelmaking process.

Plastic recycling is becoming more sophisticated these days with the
various forms and grades of plastic being marked with identifying labels
to expedite the recycling process.

I personally don't like to see cars recycled that way as it creates a
dire shortage of raw materials for hotrod builders like myself. In the
old days you could find old cars in just about every backyard in this
country. Not so nowadays and the building of hotrods will necessarily be
forced to change their tactics in the future because of this.

Krypsis