What makes A514 (T-1) steel so strong?

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?
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On Fri, 11 Mar 2016 13:45:44 -0600, Ignoramus30666

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.
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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
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On Sat, 12 Mar 2016 05:15:53 -0600, Ignoramus16966

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.
--
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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
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On Sat, 12 Mar 2016 14:51:54 -0600, Ignoramus16966

A514 ought to be a good choice for your application.
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Thanks! Very excited!
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On Sat, 12 Mar 2016 15:54:27 -0600, Ignoramus16966

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.
--
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On Sat, 12 Mar 2016 17:21:33 -0500, Ed Huntress

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.
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wrote:

So what is strong, not too expensive and easy to weld? --jsw
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On Sat, 12 Mar 2016 18:56:02 -0500, "Jim Wilkins"

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.
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I will not be doing welding. There is a company tta takes your flatbed and adds a gondola top.
i
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On Sun, 13 Mar 2016 17:19:35 -0500, Ignoramus27049

It sounds like you're ready to roll...er, to scrap. <g>
Good luck with it.
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On Sat, 12 Mar 2016 14:51:54 -0600, Ignoramus16966 wrote:

30 years without significant rust is kind of the expectation around here. It probably came from down south, or perhaps the Southwest.
30 years of service in states where they salt the roads -- that would make it rust out.
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Yes, maybe it was somewhere in the dry warm state mos of its life.
My beavertail semi trailer is the same way.,
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"Ignoramus30666" <

Carbon...
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On Fri, 11 Mar 2016 18:33:09 -0500, "Phil Kangas"

Carbon for strength, and vanadium/chromium for toughness? Many hand tools/wrenches are chrome/vanadium steel.
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