On Sat, 12 Mar 2016 18:56:02 -0500, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Sat, 12 Mar 2016 17:21:33 -0500, Ed Huntress
wrote:

On Sat, 12 Mar 2016 15:54:27 -0600, Ignoramus16966
wrote:

On 2016-03-12, Ed Huntress wrote:
On Sat, 12 Mar 2016 14:51:54 -0600, Ignoramus16966
wrote:

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

A514 ought to be a good choice for your application.


Thanks! Very excited!

If you're going to weld it, check around. The basic recommendations
are dual-shield and stick, but it may need pre-heat. Check with the
experts.

Keep in mind that A514 plate is generally sold in the
quench-and-temper, heat-treated condition. Carbon content is low,
but
the material changes phases when it's hardened, like most ferrous
metals, and the phase change results in a change in density --
besides
the changes from heating and cooling.

I should have followed up by saying that the density change puts a
lot
of stress on the weld, and makes it prone to cracking. It has some
of
the properties of welding high-carbon steel. But someone with
experience can tell you how to get it right.

--
Ed Huntress

So what is strong, not too expensive and easy to weld?
--jsw

In volumes like the plate Iggy is talking about, nothing.

It may not be difficult to weld A514; I don't know. But you have to do
it right.

--
Ed Huntress