On 2016-03-12, Ed Huntress wrote:
On Sat, 12 Mar 2016 05:15:53 -0600, Ignoramus16966
wrote:

On 2016-03-11, Ed Huntress wrote:
On Fri, 11 Mar 2016 13:45:44 -0600, Ignoramus30666
wrote:

A514 (T-1) steel seems to possess remarkable properties, being 100,000
psi strong, and yet has a very unremarkable composition. A little
vanadium and a little chromium. What exactly is it, that makes it so strong?

It's a HSLA (high-strength, low-alloy) structural steel. Among alloy
steels, 100 kips is not really that strong, but it's strong compared
to low-carbon steels and to lesser structural grades like A36.

HSLA steels are witches' brews of low alloys that combine to produce
good strength. Some, like chromium, greatly increase the ability of
carbon to form martensite. Thus, 4130 (0.30% carbon) and A514 (0.15%
carbon) can be quenched-and-tempered to much higher strengths than can
plain carbon steel of the same carbon content.

A514 also has some manganese and molbdenum, which have similar
effects.

Be careful with that "T1" designation. That's US Steel's old trade
name for it. It's also the designation for a high-strength grade of
high-speed steel that contains tungsten rather than molybdenum.


Thanks. It looks like the alloyed metals do not add strength, instead
they help form small grains of iron and ferrites, which itself makes
the metal strong.

i

You're on the right track, but if you have a need to understand it
more deeply, you'll find a lot of technical info on HSLA steels.

A514 gets most of its strength from martensite conversion
(qhuench-and-temper), and the alloy ingredients augment that process
with the low carbon level. At the same time, the combination of low
carbon and the alloy give it pretty decent ductility and elongation.
Those properties are very important in structural applications, to
avoid precipitous failure.


Ed, this steel is going to be the bottom of my scrap gondola trailer
that someone will make for me from my flatbed trailer.

My expectation is that, just as Jon Elson saw with his gun target, I
can drop heavy solid scrap pieces from up top without damaging the
bottom.

I was very lucky in that a few months ago, I bought a Fruehauf flatbed
semitrailer than was untouched by rust DESPITE being 30 years
old. (How this is even possible, is beyond me, but I have pictures to
prove it).

I bought it with the express purpose of making a gondola. My current
gondola is actually a post-consumer garbage hauling trailer and is
very weak and rusted out.

i