Chromium Car

Hard chrome, also known as industrial chrome or engineered chrome, is used to reduce friction, add wear resistance, or increase corrosion resistance. It is very hard, measuring between 66 to 70 HRC. Hard chrome tends to be thicker than the decorative treatment, typically ranging from 0.075 to 0.25 millimetre (0.0030 to 0.0098 in), but can range from 0.005 to 0.01 mil (0.00013 to 0.00025 mm). Surface defects and roughness are amplified, because hard chrome does not have a leveling effect. Hard chromium plating is subject to different types of quality requirements depending on the application, for instance, the plating on hydraulic piston rods are tested for corrosion resistance with a salt spray test.
Automotive use
Formerly most decorative items affixed to cars were referred to as "chrome", by which phrase was actually meant steel that had undergone several plating processes to endure the temperature changes and weather that a car was subject to outdoors. The most expensive and durable process involved plating the steel first with copper, and then nickel, before the chromium plating was applied.