65Mn steel plate, manganese improves hardenability, φ 12mm steel can be quenched thoroughly in oil, and its surface decarburization tendency is smaller than that of silicon steel. The comprehensive mechanical properties after heat treatment are better than that of carbon steel, but it has overheating sensitivity and tempering brittleness. It can also be used for making spring rings, valve springs, clutch springs, brake springs and cold drawn steel wire cold coil springs. The strength, hardness, elasticity and hardenability of 65Mn steel plate are higher than those of 65 steel. It has the tendency of overheating sensitivity and tempering brittleness, and water quenching has the tendency to form cracks. The machinability in annealed state is acceptable, the cold deformation plasticity is low, and the weldability is poor.