RENDERING METAL with a Blinn shader

(1) choose a Blinn Shader

(2) reduce the Diffuse (essential for metal!)

(3) reduce Specular Rolloff, increase Eccentricity

(4) use a high-frequency noise Bump Map (repeatUVto1000)

(5) add a fractal specular map with warm and cool color Gain

(6) add fractal specular map with warm and cool Offset.

(7)Map the Color Offset with a noisy Hue Ramp Texture (to add a heat-distressed irridescence).

your DONE

note:

This solution works well for weathered and corroded metals.

For shiny new metal or chrome, use a good REFLECTION MAP.