Step one:
Open a new document, create a new layer, then draw a rectangular selection.

Step two:
Double-click on the Gradient tool, and in the Gradient Tool options palette, choose "Copper" for your Gradient.

Step three:
Drag this copper gradient horizontally from the left side of your selection to the right side of your selection to fill your selection with a copper gradient.

Step four:
Go under the Image menu, under Adjust and choose Desaturate to remove all the color, and create your steel bar.

Step five:
The effect is essentially complete, but these bars tend to look better in groups, so you can Command-click (PC: Control-click) on your Bar layer's name (in the layers palette) to select it. Then you can hold the Option key (PC: Alt key) and drag yourself a copy or two of the bar. Group it near the other bars. Your bars on are their own layer, so you can now just drag them into your main interface, or use them however you want.

Step six:
This last step is totally optional, but if you like a weathered effect to your bars, you can go under the Filter menu, under Brush Strokes, and choose Sprayed Strokes. Set the Stroke Length to 20, the Spray Radius to "0", and the Spray Direction to Horizontal and click OK.I also added a drop shadow (Layer menu>Effects>Drop Shadow) to enhance the effect