Grant Erwin wrote:

Most steel made in this country now comes from melted-down cars, not
from mined iron ore. Such steel meets minimum specifications but you
may find anomalies like local hard spots (where a chromed ball bearing
was melted in for example). Many so-called "mild steels" today will
harden somewhat if heated and quenched strongly.

Maybe that's what he was talking about. - GWE

Jim Stewart wrote:

A couple of weeks ago at the recycling center, a
welder was unloading some 1/2" square steel bar.
I asked him if it was mild steel and he replied
"yes, old mild steel, the best" I've heard
references to "old steel" being better than "new
steel" and I've never understood what the difference
is.


http://www.designnews.com/article/CA405992?nid=2334
"As automakers work to improve both fuel efficiency and safety, they increasingly need to add some lean muscle to their vehicles.
Strong, lightweight structural components made from Advanced High Strength Steels (AHSS) may be just what the doctor ordered.

This diverse group of multiphase steels with high strain hardening rates generally offers yield and tensile strengths as least twice
as high as conventional stamping steels. Their tensile strenghts, for instance, start at roughly 500 MPa. So AHSS can certainly help
automakers cut weight of body structures without sacrificing strength. Yet the advanced steels do have some cost and manufacturing
barriers to overcome before they can more widely displace their lower-strength predecessors. The Great Designs in Steel seminar,
held last month in Livonia, MI, served as good progress report on these advanced steels.
"
and the text goes on to more and more info.

AHSS might be something to deal with someday.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder