I. Technical requirements for heat treatment of bucket and spade teeth
The purpose of heat treatment of ZGMnl3 and ZGMnl3Re high manganese steels is to ensure that a single austenite structure can be obtained after water toughening treatment. Carbides should be avoided as far as possible (if present, the strength and wear resistance of steels will be severely reduced). In addition, bucket teeth or spade teeth are made of low alloy steel. In order to pursue large wearable amount and prolong service life, the heat treatment process of quenching and low temperature tempering is adopted. The lath martensite (dislocation martensite) obtained has relatively high strength, hardness, high plasticity and toughness, and its comprehensive mechanical properties are higher, and the surface and toughness are higher. The hardness of the heart ranges from 44 to 52 HRC.
II. Heat treatment process
Usually the material used for bucket teeth and shovel teeth is high manganese steel (wear-resistant steel). In order to obtain the required structure, the general heat treatment process is solution treatment (water toughening treatment). The solution temperature of ZGMnl3 steel is 1050-1080 C, and ZGMnl3Re is 1000-1030 C. The holding time should be determined according to the size, thickness of the parts and the quantity of the furnace. Its principle is to ensure the thorough combustion, so that the carbides are fully and fully filled. It dissolves in austenite. After heat preservation, it can be rapidly cooled to form a single austenite structure, which is soft and tough. Carbide precipitation is not allowed. Heating equipment is usually large high temperature box furnace or salt bath furnace. Because of the low thermal conductivity, in order to ensure the consistency of internal and external temperature difference and prevent cracking, it should be preheated at 600-650 C, and at the same time, the time of solid solution and heat preservation should be reduced.