Steel Strength at Cold Bend 2

[David B]

I want to make a 90-degree cold bend in a .25” x 3.5” x 17” long 1018 Cold Finish Mild Steel rectangular bar -- 4” from one end. The 13” leg would sit flat and the 4” leg would be vertical. (I could alternately use .25” x 4” x 17” Hot Roll A36 Mild Steel.) My inquiry concerns the steel strength at the 90-degree bend, which had been deformed beyond its modulus of elasticity. I intend to impose a force of 2,000 lbs., evenly distributed, onto a 3.5” x 3.5” x .75” (12.25 sq.in.) High Density Polyethylene (HDPE) block mounted directly to the inside face of the 4” high angle. Would a 2,000-lb. force be sufficient to cause the 90-degree bend in the steel to “flatten out” in any way? I’m guessing there’d be little, if any, deflection at that 90-degree bend, but I’d like to get feedback. Thanks.

 

Are you asking us to perform calculations?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[David B]

By no means am I asking for calculations. I seek input on experiences, and simply want info about what happens to steel strength molecularly at a 90-degree bend once it exceeds its modulus of elasticity. Can such steel resist relatively minor forces? If my question rubs anyone the wrong way, I apologize. I realize I gave far too much information, but did so only to paint a picture. I very well could have cited a bend in a wire coat hanger -- and inquired about what general forces could be applied before an expected failure. The steel strength principles are generally the same.

 

[3DDave]

Good news. Steel hasn't got molecules. And modulus of elasticity isn't something that can be exceeded. It's a property, like color. There are many materials science and engineering courses and books to give a basis for your question and they will likely also produce a sufficient answer.

https://www2.virginia.edu/bohr/mse209/class.htm

may be a start.

 

[David B]

Oops on the molecular comment. And the modulus of elasticity remark should have been yield strength. I know that ASTM A36 has a yield strength of 36,000 psi and an allowable bending stress of 22,000 psi. That makes calculations easier. Those properties allow steel to deform steadily as stress is increased beyond its yield strength. I was specifically seeking info on that ductility and the strength of steel material AT a 90-degree cold bend. I've looked at many sources, but to date, have come up empty. But I'll look at the suggested link you sent. Thanks.

 

[David B]

Please ignore my original post. I am in WAY over my head for such a small project.

 

Good news. Steel hasn't got molecules.

Except for the Fe3C hiding in plain (or plane) sight.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[3DDave]

Sure. As confirmed with crystallography. Lots of amorphous steels in production?

EDIT: I'm aware that if one works hard at it one can use crystallography to analyze molecules; such as DNA. But steel is already crystaline.