Metal Texture Intro
The aim of this tutorial is to teach you some flexible methods for creating realistic metal in Photoshop. This tutorial deals with making corroded metal, but in reality you can skip some steps or add new ones for a wide variety of metal mayhem.
Part 1 Gradients and Noise.

- On a new layer create a gradient with these settings
. The colors I used were #686B73 and #ADB5BC - Then go to Filter->Noise->Add Noise. And use these settings Noise Settings(opens in popup)
- Go to Image->Adjustments->Levels and Adjust the levels (see the The final image. how to use photoshop levels tutorial for more information )
- Duplicate the layer with the silver gradient, and name the layer 'metal rust'
Part 2 Rust (optional).

- Select the 'metal rust' layer from part one, go to Image->Adjustments->Hue and Saturation, select the colorize box and mess around with photoshop's hue and saturation till you get a bright orangish-red color.View the Settings I used
- Now you want only parts of the rust to be visible so to hide some of the rust add a layer mask to the rust layer (layer->add layer mask or using the icon in the layers panel).
- After creating the mask select the layer mask portion of the layer
. Set white as your background color and black as the foreground color. Goto Filter->Render Clouds. - Using this method rust tends to be to spread out, or not strong enough in some places, you should fine tune the rust effect using levels. Image->Adjustments->Levels. (it will change the contrast of the clouds in the layermask, and hide more of the rust layer). Another thing you can try is using dodge and burn.
Part 3 Brushing and Details.
Brushing is necessary to create those, imperfections, scratches and blotches that are of so important in creating a realistic metal texture. There are many different things that you can do here, I will just explain some of the techniques that I use.
Minor Scratches

Scrapes and scratches are irregularities in the metal surface.
Create a new layer and set its blending mode to soft light and its opacity to around 50 percent. Then choose a 1 pixel, white, brush and then start drawing the scratches.
Deeper scratches

Create a new layer and set its blending mode to soft light. Then choose a 1 pixel, white, brush and then start drawing the scratches. Once you are done duplicate the layer. Move it slightly to the left, then press ctrl+I or goto Image->Adjustments->Invert
Dents

Choose a 5 pixel, white brush. Go to the brushes pallete (windows->brushes). From the window turn on scattering, then press 'brush tip shape' and increase the spacing to about 500 percent.
Click on shape dynamics, increase the size jitter to about 10 percent and the roundness jitter to 100 percent
Then brush the dots fairly evenly along the texture. Right click choose layer styles and use the following settings. (opens in popup)
Bumps
Bumps used in this metal texture are created using a similar process. Just different layer styles

This is the final result of the tutorial. If you liked this tutorial here are some other tutorials that you may like.
Photoshop Wood TexturePhotoshop Pixel Detailing effects