What is the Hardest Metal?
The hardest known metal alloy, and the hardest known metal in general, is a type of carbon steel, Alloy 1090. With a tensile strength of .84 GPa (122,000 psi) and a yield strength of .64 GPa (67,000 psi), carbon steel is surpassed in hardness only by very hard nonmetals, such as ruby, diamond, or aggregated diamond nanorods. The best high-carbon steels rate an 8 on the Mohs scale of hardness, relative to ruby at 9 and diamond at 10. The hardest metals are still somewhat soft in comparison to the strongest nonmetals, based on the strongest bonds in chemistry, the sp2 bond between carbon atoms. High-strength carbon steel goes through a process of tempering and annealing to make it harder. After this process is complete such steel is called strengthened steel, the hardest metal available. Carbon contents as great as 2% may be present in the hardest metal. Another one of the hardest metals is tungsten carbide, used in both the military and for top-shelf sports equipment. Depleted uranium,
