420 is a hardenable, martensitic stainless steel that is a modification of Alloy 410. Similar to 410, it contains a minimum of 12% chromium, just sufficient enough to give corrosion resistant properties. This material has typically been used for parts requiring corrosion resistance and oxidation resistance up to 800 F (427 C) and hardness at room temperature within the range 40 to 55 HRC when heat treated. Maximum corrosion resistance is attained only in the fully hardened condition. It is never used in the annealed condition. Certain design and processing procedures may cause this material to become susceptible to stress-corrosion cracking. Grade 420 is often used for Cutlery, Surgical & Dental Instruments, Scissors, Fasteners and Firearms. (UNS S42000)
