H11 steel combines high hardness and toughness, and exhibits outstanding performance under extreme working conditions. H11 steel has excellent hardenability and can be hardened by air cooling, greatly reducing the risk of mold heat treatment deformation and cracking; H11 steel has stable thermal strength and oxidation resistance under medium temperature environment, and can maintain good mechanical properties within 600 ℃. It has strong resistance to cold and hot fatigue, and is not easy to crack under frequent cold and hot cycles. H11 steel has excellent resistance to low melting point alloys such as aluminum and magnesium.