Alloy 420 is a martensitic stainless steel of the 12% Chromium type. Due to it’s Chromium content 420 will achieve high hardness. Alloy 420 is used in many different applications including surgical and dental instruments, scissors, needle valves, gears, ball bearings, magnets etc. Alloy 420 should not be used for springs or heavily stressed parts that require to be operated at sub-zero temperatures.
Ask an Aviation Metals expert