Ferrium S53 was developed for use as a structural corrosion resistant steel for aircraft landing gear. S53 has a corrosion resistance equivalent to 440C, strength equivalent to or better than 300M (AMS 6257A) and SAE 4340 (see Mechanical Properties), optimum microstructure features for maximum fatigue resistance, and a surface hardenability equal to or greater than 67 HRC for wear and fatigue. This datasheet is an update to Alloy Digest SS-942 and SS-1003. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: SA-589. Producer or source: QuesTek Innovations, LLC.