steel grain?

[structSU10]

I am reviewing some calculations and there is this general note:

"Orient steel grain structure perpendicular to bend lines for all bent plates used as connection material..."

Anyone know the reason for this? I never heard of any issue with orientations of a steel plate prior to bending.

 

[ToadJones]

I think plate material has a "grain" from the rolling process. I think the Green Book has some commentary on this.
I believe there is different min. bend radii depending on which way you are bending...with or across the "grain".

 

[ToadJones]

Pg 4-174 in the Green Book

 

[ToadJones]

10-160 in the Black Book

 

[dhengr]

Toad is right, the rolling process does tend to cause a grain orientation in the steel. When this rolling grain orientation is parallel to the bend line the plate does have a tendency to rip or split, on the tension side, along the bend line. Thus, you may have to increase the bending radius as AISC suggests. You can bend to a tighter radius when the grain runs perpendicular to the bend line, a more favorable tensile orientation. Any edge nicks and the like can cause problems in either direction so it is common to dress the edges of a plate a little at the bend lines.

 

[structSU10]

That makes sense, good to know, thanks for the replys!