The corrosion resistance of chromium was found by accident

Addition of chromium imparts hardness, strength, wear resistance, heat resistance, and corrosion resistance to steels. In 1913 Harry Brearley of Sheffield was experimenting with alloy steels for gun barrels, and among the samples which he threw aside as being unsuitable was one containing about 14 percent of chromium. Some months later he noticed that most of the steels had rusted, but the chromium steel remained bright. This led to the development of stainless steels. Chromium alloys are commonly used in axles, bolts, springs, and studs for automobiles. They are also used in tool for chisels, dies, drills, files, knives, and shears.