“…1.7038, which has high rupture strength and creep strength at high temperatures, good impact toughness at low temperatures, good hardenability, no overheating tendency, small quenching deformation, general plasticity at cold deformation and good machinability. Poor weldability, preheating before welding, and heat treatment after welding to eliminate stress, generally used after quenching and tempering, can also be used after medium and highfrequency surface quenching or quenching and low and medium temperature tempering [1,2]. It is widely used for important structural parts under high load conditions, such as transmission parts of vehicles and engines, rotor, main shaft, transmission shaft under heavy load of the steam turbine generator, large section parts, forgings with higher strength and larger quenched and tempered section than 35CrMo steel, such as big gear for locomotive traction, transmission gear of supercharger, rack, rear axle, connecting rod and spring clamp under great load.…”