Most of the carburized steel is low carbon steel or low alloy steel. The specific method is to place the workpiece in the active carburizing medium and heat it to 900-950 degrees Celsius. After holding for enough time, the decomposed active carbon atoms in the carburizing medium are infiltrated into the surface of the steel piece, and thus high carbon was obtained in the surface layer and the original composition was maintained in the heart. Similarly, low-temperature nitriding treatment is used. This is a common heat treatment process for metal materials. Carburizing process often works together with quenching, surface quenching or tempering treatment to get the desired hardness results. Carburizing process can only change the physical properties of a certain depth below the surface of the workpiece so as to improve the wear-resistance of the workpiece. The deep physical properties such as stiffness and bending resistance of the workpiece can not be strengthened.