Spheroidizing annealing technology of H13 hot work die steel
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A technology of hot-working die steel and spheroidizing annealing, which is applied in the field of heat treatment of die steel, can solve the problems of small carbide size, poor quality, poor structure, etc., and achieve the effect of improving transverse impact toughness
Active Publication Date: 2017-06-09
CENT IRON & STEEL RES INST
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As a result, the annealed state of H13 steel leaves the factory with a lower level of spheroidizing annealing, and the quality is also poor
The main reason is that the structure before isothermal annealing is not pretreated, and the uneven forged structure remains
In recent years, to solve the problem of poor annealing structure of H13 steel, researchers have added normalizing process on the basis of traditional isothermal annealing. The normalizing temperature is generally 1000-1100°C. However, the carbide size is too small, the hardness is high, the carbide distribution still has a certain direction, and the spheroidizing effect has not reached the super quality level of the NADCA 207-2003 standard
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Embodiment 1
[0021] Select the size of the section after forging For round bars, the specific heat treatment process is as follows:
[0022] (1) After forging The steel billet is cooled to 430°C, loaded into the furnace, heated to 750°C at a heating rate of 70°C / h, preheated and kept for 1 hour, and then heated to 1000°C at a heating rate of 70°C / h, and then the charge is fully protected. Incubate for 3h, then furnace-cooled to 500°C and air-cooled.
[0023] (2) The hot charging furnace is heated to 900°C at a heating rate of 70°C / h, and the charge is kept for 0.5h after penetration, and the furnace is air-cooled to complete the pretreatment process.
[0024] (3) Load the furnace at 300°C, including the forged billet (comparison sample) and the pretreated billet, heat up to 880°C at a heating rate of 70°C / h, hold for 4 hours, and cool down to a cooling rate of 15°C / h After holding at 760 °C for 8 hours, it is cooled to 455 °C with a cooling rate of 15 °C / h and air-cooled to complete t...
Embodiment 2
[0027] Select the size of the section after forging For round bars, the specific heat treatment process is as follows:
[0028] (1) After forging The steel billet is cooled to 480°C, loaded into the furnace, heated to 750°C at a heating rate of 70°C / h, preheated and kept for 1 hour, and then heated to 980°C at a heating rate of 70°C / h, and then the charge is fully protected. Incubate for 5h, then furnace-cooled to 480°C and air-cooled.
[0029] (2) The hot charging furnace is heated to 900°C at a heating rate of 70°C / h, and the charge is kept for 1 hour after being fully protected, and the furnace is air-cooled to complete the pretreatment process.
[0030] (3) Load the furnace at 370°C, including the forged billet (comparative sample) and the pretreated billet, heat up to 880°C at a heating rate of 70°C / h, hold for 6 hours, and cool at a cooling rate of 15°C / h to 880°C After holding at 760°C for 10 hours, it is cooled to 500°C at a cooling rate of 20°C / h and air-cooled t...
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Abstract
The invention provides a spheroidizing annealing technology of H13 hot work die steel and belongs to the field of die steel heat treatment technologies. The spheroidizing annealing technology of the H13 hot work die steel comprises the steps that (1) a forged H13 steel blank is cooled to the temperature of 400-500 DEG C, the cooled H13 steel blank is fed into a furnace, the temperature is raised to 720-750 DEG C at the temperature raising speed of 25-80 DEG C per hour for preheating, the temperature is kept for 1-2 hours, the temperature is then raised to 980-1050 DEG C at the temperature raising speed of 25-80 DEG C per hour, after all the furnace charge reaches the temperature, the temperature is kept for 3-5 hours, then the temperature of the forged H13 steel blank is lowered to be not higher than 550 DEG C through furnace cooling, and air cooling and discharging are conducted; hot charging is conducted, the temperature is raised to 900-950 DEG C at the temperature raising speed of 25-80 DEG C per hour, after all the furnace charge reaches the temperature, the temperature is kept for 0.5-1 hour, air cooling and discharging are conducted, and then the pre-treatment process is completed; and charging is conducted at the temperature 300-400 DEG C, the temperature is raised to 880+/-10 DEG C at the temperature raising speed of 25-80 DEG C per hour, the temperature is kept for 4-6 hours, the temperature is lowered to 760+/-10 DEG C at the cooling speed of 15-20 DEG C per hour, after the temperature is kept for 8-12 hours, the H13 hot work die steel is cooled to be lower than or equal to 500 DEG C at the cooling speed of 15-20 DEG C per hour, and then air cooling and discharging are conducted. The spheroidizing annealing technology of the H13 hot work die steel has the advantages that carbides are evenly distributed in the structure, the structure is refined, the defects of network carbides and the like in an original structure are eliminated, and the annealing hardness is lowered.
Description
technical field [0001] The invention belongs to the field of heat treatment technology of die steel, in particular to a spheroidizing annealing process of H13 hot work die steel. It is suitable for improved annealing of H13 steel after forging and unqualified annealing structure. Background technique [0002] H13 steel is currently the most widely used hot work die steel. This type of steel is usually used in rapid cooling and rapid heating and high temperature and high pressure environments. Its main failure modes are thermal fatigue cracks, coarse cracks, plastic deformation, wear, etc. Among them, thermal fatigue Crack is the most important failure form affecting the life of hot work die. It is generally believed that strength and tempering stability are the most important factors affecting thermal fatigue resistance, while high impact toughness is conducive to local stress relaxation and preventing crack propagation. Strength and plasticity may have different effects o...
Claims
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