Quenching and tempering process of round steel

Abstract

The invention relates to the technical field of round steel hardening and tempering, and discloses a round steel hardening and tempering process which comprises the following specific process steps: S1, quenching: before round steel is charged into a furnace, oxide skin and oil dirt impurities on the surface need to be removed, and pretreatment can be performed by adopting an acid pickling, sand blasting or mechanical polishing method; s2, tempering is conducted, specifically, the quenched round steel is put into a tempering furnace and heated to the tempering temperature at the heating rate of 100-150 DEG C / h; after heat preservation is finished, a heating power source is turned off, and the round steel is taken out after being cooled to the room temperature along with the tempering furnace; according to the process, the product quality can be improved, and the round steel is more uniform in structure and more stable in performance by accurately controlling the heating temperature, the heat preservation time, the quenching cooling speed and the tempering temperature and time process parameters, so that the comprehensive mechanical properties of hardness, strength, toughness and plasticity of the round steel are remarkably improved; the requirements of different fields on high-quality round steel are met, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of round steel tempering, in particular to a round steel tempering process. Background Art

[0002] The quenching and tempering of round steel is an important means to improve the comprehensive mechanical properties of round steel, and is widely used in the fields of machinery manufacturing, automobiles, and aerospace. The traditional quenching and tempering process of round steel has some shortcomings in practical applications. For example, the temperature control during the heating process is not precise enough, which easily leads to oxidation and decarburization of the round steel surface; the cooling rate during the quenching cooling process is uneven, which affects the microstructure and properties of the round steel; the improper control of temperature and time during the tempering process leads to the problem that the strength and toughness of the round steel cannot achieve the best match. These problems not only affect the quality and performance of the round steel, but also increase the production cost and production cycle. Therefore, it is necessary to optimize and improve the traditional quenching and tempering process of round steel to improve the quenching and tempering quality and production efficiency of round steel and meet the needs of modern industry for high-performance round steel. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a round steel tempering process, which has the advantage of improving quality and solves the problem of low round steel tempering efficiency.

[0004] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a quenching and tempering process of round steel, comprising the following specific process steps: S1 quenching, before the round steel is loaded into the furnace, the oxide scale and oil impurities on the surface need to be removed, and pickling, sandblasting or mechanical grinding methods can be used for pretreatment; Place the round steel into a heating furnace preheated to 300-400℃, and heat it to the quenching temperature at a heating rate of 80-100℃ / h. For 45# steel, the quenching temperature is generally 840-860℃; for 40Cr steel, the quenching temperature is generally 850-870℃; The round steel is kept warm at the quenching temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 1-1.5min / mm; After the insulation is completed, the round steel is quickly taken out and placed vertically in the quenching tank for quenching. The quenching medium can be water, salt water, or oil. The appropriate quenching medium is selected according to the chemical composition and performance requirements of the steel. After the round steel is cooled to room temperature in the quenching medium, take it out and clean and dry it in time to remove the quenching medium and oxide scale impurities remaining on the surface; S2 tempering: put the quenched round steel into the tempering furnace and heat it to the tempering temperature at a heating rate of 100-150℃ / h; The round steel is kept at the tempering temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 2-3min / mm; After the insulation is finished, turn off the heating power supply, let the round steel cool down to room temperature in the tempering furnace and then take it out; S3 quality control and inspection: during quenching and tempering, thermocouples and temperature controllers should be used to monitor the furnace temperature and the temperature of the round steel in real time to ensure that the temperature control accuracy is within ±5°C; Regularly test and adjust the cooling performance of the quenching medium to ensure that the cooling capacity of the quenching medium meets the process requirements; The hardness, strength, toughness and plasticity performance indicators of the quenched and tempered round steel shall be tested in accordance with the relevant national standards or industry standards; Conduct metallographic inspection on the round steel after quenching and tempering to observe the morphology, distribution and grain size of the organization to ensure that the organization meets the process requirements and product performance requirements Preferably, for the S1 quenching, for 45# steel, salt water or water is usually used as the quenching medium; for 40Cr steel, oil is generally used as the quenching medium.

[0005] Preferably, the S2 tempering temperature is generally 550-650°C for 45# steel and 500-600°C for 40Cr steel.

[0006] Preferably, during the heating process, care should be taken to prevent oxidation and decarburization of the round steel surface, and a controlled atmosphere protection or anti-oxidation coating method may be used.

[0007] Preferably, during the quenching process, it should be ensured that the round steel is cooled evenly in the quenching medium to avoid local overheating or insufficient cooling.

[0008] Preferably, the tempering temperature and holding time should be strictly controlled during the tempering process to avoid insufficient tempering or excessive tempering.

[0009] (III) Beneficial effects Compared with the prior art, the present invention provides a round steel quenching and tempering process, which has the following beneficial effects: 1. The quenching and tempering process of round steel can improve product quality. By accurately controlling the heating temperature, holding time, quenching cooling speed, tempering temperature and time process parameters, the organization of the round steel is more uniform and the performance is more stable, thereby significantly improving the hardness, strength, toughness and plasticity of the round steel. The comprehensive mechanical properties meet the high quality requirements of round steel in different fields and improve production efficiency. The optimized process adopts preheating, rapid heating, precise temperature control and rapid cooling measures, shortening the heating and cooling time, improving production efficiency and reducing production costs.

[0010] 2. The round steel tempering process reduces energy consumption. Accurate temperature control and reasonable process parameter settings can reduce energy waste and energy consumption in the production process, meet the requirements of energy conservation and emission reduction, and extend the service life of equipment. The optimized process reduces the oxidation and decarburization phenomenon during the heating process, reduces the corrosion and wear of the heating furnace and quenching tank equipment, extends the service life of the equipment, reduces equipment maintenance costs, and improves product reliability and stability. The improved round steel tempering process can effectively reduce product quality fluctuations, improve product consistency and reliability, and provide better guarantees for subsequent mechanical processing and use. DETAILED DESCRIPTION

[0011] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0012] The raw materials are round steel made of high-quality carbon structural steel or alloy structural steel that meets the standard requirements, such as 45 steel and 40Cr; Equipment and tooling Heating furnace: adopts controlled atmosphere resistance furnace or gas furnace, with precise temperature control and uniform heating performance.

[0013] Quenching tank: The quenching tank is equipped with a circulating cooling system and a stirring device to ensure uniform temperature and rapid cooling of the quenching medium.

[0014] Tempering furnace: Box-type tempering furnace, capable of accurately controlling tempering temperature and holding time A quenching and tempering process of round steel, comprising the following specific process steps: S1 quenching, before the round steel is loaded into the furnace, it is necessary to remove the oxide scale, oil impurities on the surface, and the pretreatment can be carried out by pickling, sandblasting or mechanical grinding; Place the round steel into a heating furnace preheated to 300-400℃, and heat it to the quenching temperature at a heating rate of 80-100℃ / h. For 45# steel, the quenching temperature is generally 840-860℃; for 40Cr steel, the quenching temperature is generally 850-870℃; The round steel is kept warm at the quenching temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 1-1.5min / mm; After the insulation is completed, the round steel is quickly taken out and placed vertically in the quenching tank for quenching. The quenching medium can be water, salt water, or oil. The appropriate quenching medium is selected according to the chemical composition and performance requirements of the steel. For 45# steel, salt water or water is usually used as the quenching medium; for 40Cr steel, oil is generally used as the quenching medium; After the round steel is cooled to room temperature in the quenching medium, take it out and clean and dry it in time to remove the quenching medium and oxide scale impurities remaining on the surface; S2 tempering: put the quenched round steel into the tempering furnace and heat it to the tempering temperature at a heating rate of 100-150℃ / h. For 45 steel, the tempering temperature is generally 550-650℃; for 40Cr steel, the tempering temperature is generally 500-600℃; The round steel is kept at the tempering temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 2-3min / mm; After the insulation is finished, turn off the heating power supply, let the round steel cool down to room temperature in the tempering furnace and then take it out; S3 quality control and inspection: during quenching and tempering, thermocouples and temperature controllers should be used to monitor the furnace temperature and the temperature of the round steel in real time to ensure that the temperature control accuracy is within ±5°C; Regularly test and adjust the cooling performance of the quenching medium to ensure that the cooling capacity of the quenching medium meets the process requirements; The hardness, strength, toughness and plasticity performance indicators of the quenched and tempered round steel shall be tested in accordance with the relevant national standards or industry standards; Carry out metallographic structure inspection on the round steel after quenching and tempering to observe the morphology, distribution and grain size of the structure to ensure that the structure meets the process requirements and product performance requirements.

[0015] Furthermore, during the heating process, care should be taken to prevent oxidation and decarburization of the round steel surface, and controlled atmosphere protection or anti-oxidation coating can be used; During the quenching process, ensure that the round steel is cooled evenly in the quenching medium to avoid local overheating or insufficient cooling; During the tempering process, the tempering temperature and holding time should be strictly controlled to avoid insufficient tempering or excessive tempering.

[0016] Furthermore, the process can improve product quality. By precisely controlling the heating temperature, holding time, quenching cooling speed, tempering temperature and time process parameters, the structure of the round steel can be more uniform and the performance can be more stable, thereby significantly improving the comprehensive mechanical properties of the round steel in terms of hardness, strength, toughness and plasticity, meeting the high quality requirements of round steel in different fields and improving production efficiency. The optimized process adopts preheating, rapid heating, precise temperature control and rapid cooling measures, which shortens the heating and cooling time, improves production efficiency and reduces production costs.

[0017] Furthermore, the process reduces energy consumption. Precise temperature control and reasonable process parameter settings can reduce energy waste, reduce energy consumption in the production process, meet the requirements of energy conservation and emission reduction, and extend the service life of equipment. The optimized process reduces oxidation and decarburization during the heating process, reduces corrosion and wear on heating furnaces and quenching tank equipment, extends the service life of equipment, reduces equipment maintenance costs, and improves product reliability and stability. The improved round steel tempering process can effectively reduce product quality fluctuations, improve product consistency and reliability, and provide better guarantees for subsequent mechanical processing and use.

[0018] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A quenching and tempering process for round steel, characterized in that: The process includes the following specific steps: S1 quenching: before loading the round steel into the furnace, the oxide scale, oil and impurities on the surface need to be removed. Pickling, sandblasting or mechanical grinding can be used for pretreatment; Place the round steel into a heating furnace preheated to 300-400℃, and heat it to the quenching temperature at a heating rate of 80-100℃ / h. For 45# steel, the quenching temperature is generally 840-860℃; for 40Cr steel, the quenching temperature is generally 850-870℃; The round steel is kept warm at the quenching temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 1-1.5min / mm; After the insulation is completed, the round steel is quickly taken out and placed vertically in the quenching tank for quenching. The quenching medium can be water, salt water, or oil. The appropriate quenching medium is selected according to the chemical composition and performance requirements of the steel. After the round steel is cooled to room temperature in the quenching medium, take it out and clean and dry it in time to remove the quenching medium and oxide scale impurities remaining on the surface; S2 tempering: put the quenched round steel into the tempering furnace and heat it to the tempering temperature at a heating rate of 100-150℃ / h; The round steel is kept at the tempering temperature. The holding time is calculated based on the diameter and effective thickness of the round steel, generally 2-3min / mm; After the insulation is finished, turn off the heating power supply, let the round steel cool down to room temperature in the tempering furnace and then take it out; S3 quality control and inspection: during quenching and tempering, thermocouples and temperature controllers should be used to monitor the furnace temperature and the temperature of the round steel in real time to ensure that the temperature control accuracy is within ±5°C; Regularly test and adjust the cooling performance of the quenching medium to ensure that the cooling capacity of the quenching medium meets the process requirements; The hardness, strength, toughness and plasticity performance indicators of the quenched and tempered round steel shall be tested in accordance with the relevant national standards or industry standards; Carry out metallographic structure inspection on the round steel after quenching and tempering to observe the morphology, distribution and grain size of the structure to ensure that the structure meets the process requirements and product performance requirements.

2. The quenching and tempering process of round steel according to claim 1, characterized in that: For the S1 quenching, for 45# steel, salt water or water is usually used as the quenching medium; for 40Cr steel, oil is generally used as the quenching medium.

3. The quenching and tempering process of round steel according to claim 1, characterized in that: The S2 tempering temperature is generally 550-650°C for 45# steel and 500-600°C for 40Cr steel.

4. The quenching and tempering process of round steel according to claim 1, characterized in that: During the heating process, care should be taken to prevent oxidation and decarburization of the round steel surface. Controlled atmosphere protection or coating with anti-oxidation coatings may be used.

5. The quenching and tempering process of round steel according to claim 1, characterized in that: During the quenching process, it should be ensured that the round steel is cooled evenly in the quenching medium to avoid local overheating or insufficient cooling.

6. The quenching and tempering process of round steel according to claim 1, characterized in that: During the tempering process, the tempering temperature and the holding time should be strictly controlled to avoid insufficient tempering or excessive tempering.