Abstract GearMet C61 is targeted as an attractive alternative to current gear materials in applications where component redesign is not feasible but where higher core strength and toughness are required. GearMet C61 has surface wear properties and fatigue properties similar to those found in current commercial alloys, and it possesses superior core hardness and toughness. This datasheet provides information on composition, microstructure, and hardness as well as fracture toughness and fatigue. It also includes information on heat treating. Filing Code: SA-497. Producer or source: QuesTek Innovations, LLC.