On Thu, 30 Jun 2011 21:11:07 -0400, "Jim Wilkins"
wrote:


wrote in message
.. .
I needed some 3/4"x3/4"x1/8" angle iron for a project. Previously I
bought a 3-foot length in Home Depot so I headed back there. They had
an item with that description but it did not look like what I had
bought before.

I believe that "regular" angle iron is made by extrusion. These pieces
looked like someone put a 1.5" flat in a brake and bent it at right
angles (I believe the term for this is "formed"). I was reluctant to
buy this as it just did not *look* as strong as the regular extruded
type. I tried to work out the relative strengths from the Machinery's
Handbook but without success.

So the questions a

1) Am I right in assuming that the extruded angle iron is stronger
compared to the formed type? If so by how much?

2) Is there a good reason why a 72" length of stock should cost 1.5x
as much per inch as a 36" length?

Michael Koblic,
Campbell River, BC

I think your 'extruded' angle is hot-rolled steel, the 'formed' angle is
cold-rolled. Is it smooth and zinc-plated? Typically cold-rolled has a
higher yield point since it has already been deformed and moved up the
stress-strain curve by the rolling process, while hot rolled steel is in the
softer annealed condition.

If that's unclear, it's because Gwyneth is singing Do You Want to Touch Me
There on TV right now.

jsw

The "formed" angle has internal and external radius - Rolled angle has
internal radius and square outer edge.
GENERALLY the rolled material is stiffer ( at least torsionally) than
the formed angle but it does depend on the alloy and heat treating, if
any.