Some high-strength martensitic stainless steels, high-speed tool steels, and high-strength alloy steels, due to their high hardenability and alloying element strengthening. Often tempering (or tempering) after high temperature tempering, the steel carbide is properly aggregated to obtain coarse particles of carbide tempered sorbite (with spheroidizing annealing organization, and so on) state delivery plate has good The cutting performance is delivered directly after cooling, called hot rolling or forging, after hot rolling or forging and without special heat treatment. Hot (forging) termination temperature is generally 800-900 ℃, the air is generally naturally cooled, so hot (forging) state is equivalent to normalizing. And strictly normalizing heating temperature control, due to the hot (forging) the end of the temperature caused by the difference. So that the vibration ratio of steel, microstructure and properties have been well improved.
1. Many steel companies control the rolling, because the finishing temperature control is very strict, forced cooling after finishing rolling to take measures to refine the grain of steel, conveying high mechanical properties of steel. Due to the appearance of the skin covered with a layer of iron oxide, has some corrosion resistance, such as strict storage requirements not cold-rolled (rolled) delivery of steel, medium steel, medium steel plate can be in the open yard or through thatch cover and Storing the position of the non-twisted controlled cooling hot rod is the truth that the hot-rolled (forged) delivery status is better than that of a normal hot-rolled steel wire rod.
2. Cold drawn (rolled) steel hardenability, without any heat treatment and direct delivery, cold drawn, cold-rolled steel cold forming the status quo. Known as cold-drawn or cold-rolled conditions. Cold drawn steel size (rolling) state of high precision, surface quality, low appearance roughness, and has high mechanical properties, compared with the hot-rolled (forging) state. Due to the delivery status of cold-drawn (rolled) stainless steel housings without any scale and a large stress that is susceptible to corrosion or rust, the requirements for steel in cold-drawn (rolled) state, packaging, storage and transportation are relatively stringent and generally required In the custody of the Treasury, and the Ministry of Finance should pay attention to the temperature and humidity control in the state of delivery of the state, said normalizing. As normalizing heating temperature (hypoeutectoid steel AC3 +3050 ° C eutectoid steel ACCM +3050 ° C hot side than the strict temperature control,
Third, before regulating the status quo and standardizing the heat treatment of steel mills. Therefore, steel structure, uniform performance. Normalizing cooling speed, compared with the steel annealing state. Steel pearlite sheet and grain refinement increased the number of pearlite structure, which has high mechanical properties, and help to improve the low carbon steel Wei organization and eutectoid steel cementite network, Prepare for further heat treatment of the product.
