H11 alloy is a 5% chromium hot-work tool steel characterized by its incredible impact toughness and good red-hardness.The alloy is a deep-hardening, air-hardening steel that exhibits minimal size change during heat treatment. Because of its excellent resistance to thermal fatigue cracking, in addition to strong resistance to gross cracking and thermal shock, H11 is generally used in highly stressed structural parts such as aircraft landing gear and is also widely used as a structural material for critical components in aircraft missiles. H11 is also recommended for hot tooling applications where maximum resistance to cracking is required. Such applications include hot punches, die casting dies, forging dies, hot shear blades, hot gripper dies, and extrusion tooling. The tools produced from chromium hot-work steels can be cooled using water without damage as these steels have low carbon and alloy contents.