How to tell the grain direction of steel:

[ome]

Hi guys,
if i am buying from discount steel, lets say some a36 -1/4"thick and 1.125" wide in 8 foot lenghts.
I want to make some serious shelf brackets for the workshop. How do i tell the direction of grain.
So i cut 14" and bend slowly, hoping i am going against the grain.
Do i drill the holes before ot after the bending.
Thanks,
Jon

 

[Flammable_Solid]

It depends. If the pieces are still covered in mill scale (edges too) the grain direction will be that of the 8ft length. If they have sheared edges, then the short direction is the grain direction.

Short of looking at the microstructure, there isn't a good way to tell.

Unless you are bending it back 180 degrees on itself, the grain direction is not going to matter. As for drilling the holes, how accurate is the hole location to the other pieces?

 

[ome]

It depends. If the pieces are still covered in mill scale (edges too) the grain direction will be that of the 8ft length. If they have sheared edges, then the short direction is the grain direction.

Short of looking at the microstructure, there isn't a good way to tell.

Unless you are bending it back 180 degrees on itself, the grain direction is not going to matter. As for drilling the holes, how accurate is the hole location to the other pieces?

Thanks ,
if i understand you , then the accuracy if the piece is one of a pair.
I would probably set it up on our drill press.
Thanks very much,
Jon

 

[Ray C]

I'm aware that metal has a grain structure and it's of extreme importance as it relates to property phase changes during heat treating but, once a metal is in a useable condition, I was never aware that a user needed to have knowledge about the grain of the metal to use it most effectively.

My experiences with A36 (which is lengthy since I once did a fair amount of fabrication with it) is that its the lowest common denominator out there. It has terrible properties for machining because it has extremely uneven density. When drilling or sawing it in automated machines, sometimes a piece will finish in a few moments and an identical piece will take 2-3 times longer. -That's because of uneven density of the constituent components. I have noticed this time, and time again...

For basic fabrication of heavy duty tables, shelves etc... you can't beat it though. It welds like a dream with 6011, 6013 and 7018. For deep welds, use a 6011 root pass and cover with 7018. For thin pieces hit it with a layer of 6013 and call it a day.


Ray

 

[Bill C.]

Thanks ,
if i understand you , then the accuracy if the piece is one of a pair.
I would probably set it up on our drill press.
Thanks very much,
Jon

I usually follow the grain pattern of the scale. Like wood there is a pattern left by the rolling mills. If its plated then your guess is as good as mine.

 

[SE18]

grain pattern is absolutely important and you can see it as clear as grain in wood -- referring to the old-style wrought iron worked by blacksmiths back in the day

 

[pdentrem]

In this case I doubt that it will be an issue but if you have to know, polish an area to a high shine and acid etch. The grains will appear, if any, under magnification. It depends on how much work was put into the steel. Usually the grains are broken as the metal is reduced in thickness and basically will be of equal size within reason. They can be longer than wide. They are pushed and stretched as the metal runs through the rolls.

At work, some of our metals (not steels) are sensitive to grain orientation as we roll them down, even after annealing. Also we have some customers that call for some parts to be stamped with the grain in one direction and the next part at 90 degrees to the first. In this case we do see a difference under x-ray inspection.
Pierre