Overall quenching and tempering heat treatment method for round steel

Abstract

The invention relates to the technical field of round steel heat treatment, and discloses a round steel integral quenching and tempering heat treatment method which comprises the following specific steps: S1, preparing materials; s2, equipment inspection; s3, a tool clamp is prepared; s4, charging; s5, heating; s6, quenching; s7, discharging and cooling; according to the overall quenching and tempering heat treatment method for the round steel, the comprehensive mechanical performance of the round steel is improved, the surface of the round steel obtains a high-hardness martensitic structure by accurately controlling the quenching heating temperature, the heat preservation time and the cooling speed, meanwhile, a core part keeps certain toughness, and therefore the strength and toughness of the round steel are improved; through the reasonable high-temperature tempering process, quenched martensite is fully decomposed and converted, a tempered sorbite structure is formed, the plasticity and toughness of the round steel are improved, the brittleness of the round steel is reduced, the round steel has good comprehensive mechanical performance, and according to the scheme, the production efficiency and the product quality stability are improved, process parameter control is accurate, and equipment operation is stable; and waste products and inferior-quality products caused by process fluctuation are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of round steel heat treatment, in particular to a method for overall quenching and tempering heat treatment of round steel. Background Art

[0002] As an important structural material, round steel is widely used in machinery manufacturing, automobile industry, aerospace and other fields. Quenching and tempering heat treatment is an important means to improve the comprehensive performance of round steel. Through the process of combining quenching and high-temperature tempering, round steel can obtain good strength, toughness and plasticity.

[0003] In the traditional round steel tempering heat treatment process, the uneven temperature during heating and cooling can easily lead to uneven internal structure of the round steel, thus affecting its performance. In addition, too fast or too slow cooling speed during quenching, as well as improper control of tempering temperature and time, can also make the performance of the round steel unable to reach the ideal state. Therefore, it is necessary to improve and optimize the round steel tempering heat treatment process to improve the quality and performance of the round steel. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for overall tempering heat treatment of round steel, which has the advantages of improving the quality and performance of round steel and solving the problem of uneven temperature during heating and cooling.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a method for overall quenching and tempering heat treatment of round steel, comprising the following specific steps: S1 material preparation: selecting round steel of suitable specifications and materials, and ensuring that the surface of the round steel is clean and free of oil stains, rust and other impurities; S2 Equipment inspection: Check the heat treatment furnace (such as box-type resistance furnace, pit-type resistance furnace), temperature control instrument, thermocouple, quenching water tank or oil tank equipment to ensure its normal operation and reliable accuracy; S3 Preparation of fixtures: Prepare appropriate fixtures according to the size and shape of the round steel to ensure uniform heating and cooling of the round steel during heat treatment; S4 Furnace loading: Place the round steel evenly in the effective heating area of ​​the heat treatment furnace. Note that a certain distance should be maintained between the round steels to ensure uniform heat transfer. For round steels with smaller diameters, they can be loaded into the furnace by hanging; for round steels with larger diameters, they can be loaded into the furnace by laying flat; S5 Heating: According to the material of the round steel and the required quenching temperature, set the heating temperature and heating rate of the heat treatment furnace. When the furnace temperature reaches the set temperature, keep it warm for a certain period of time to make the round steel fully austenitized; S6 quenching: After the insulation is completed, the round steel is quickly taken out of the heat treatment furnace and placed in a quenching medium (such as water or oil) for quenching. During quenching, it is necessary to ensure that the round steel is quickly cooled in the quenching medium to obtain a martensitic structure. For water quenching, the round steel should be continuously moved after entering the water to ensure uniform cooling; for oil quenching, the oil should be properly stirred after the round steel enters the oil to increase the cooling rate; S7 Cooling after leaving the furnace: After the heat preservation is completed, the round steel is taken out of the heat treatment furnace and naturally cooled to room temperature in the air; S8 Inspection: Check the surface of the round steel, which should be free of cracks, deformation, oxidation and decarburization defects.

[0006] Preferably, the S3 furnace loading: the quenched round steels are evenly placed in the effective heating zone of the heat treatment furnace, and it is noted that a certain distance should be maintained between the round steels to ensure uniform heat transfer.

[0007] Preferably, the S5 heating: the heating temperature and heating rate of the heat treatment furnace are set according to the material of the round steel and the required tempering temperature. Generally speaking, the tempering heating temperature is between 500-650°C, and the heating rate is controlled at about 5-10°C / min. When the furnace temperature reaches the set temperature, it is kept warm for a certain time to allow the martensite in the round steel to fully decompose and transform. The holding time is determined according to the diameter and material of the round steel, usually 2-5h / 100mm diameter.

[0008] Preferably, the S8 inspection also includes a hardness test: a hardness test is performed on the round steel using a hardness tester, and the hardness value should meet the design requirements. Generally speaking, the hardness of the round steel after quenching and tempering treatment is between 22 and 32 HRC.

[0009] Preferably, the S8 inspection also includes metallographic inspection: metallographic inspection is performed on the round steel to observe its organizational morphology, and a tempered bainite structure should be obtained, and the structure should be uniform and free of abnormal structure.

[0010] Preferably, the S6 quenching: the quenching cooling time is determined according to the diameter and material of the round steel, usually 3-10 min / 100 mm diameter.

[0011] Preferably, the S5 heating: holding time is determined according to the diameter and material of the round steel, usually 1 - 3h / 100mm diameter.

[0012] Preferably, the S5 heating: the quenching heating temperature is between 800-900°C, and the heating rate is controlled at about 5-10°C / min.

[0013] (III) Beneficial effects Compared with the prior art, the present invention provides a method for overall quenching and tempering of round steel, which has the following beneficial effects: 1. The overall quenching and tempering heat treatment method of round steel improves the comprehensive mechanical properties of round steel. By accurately controlling the quenching heating temperature, holding time and cooling rate, the surface of the round steel obtains a high-hardness martensitic structure, while the core maintains a certain toughness, thereby improving the strength and toughness of the round steel; Reasonable high-temperature tempering process can fully decompose and transform the quenched martensite to form tempered troostite structure, improve the plasticity and toughness of the round steel, reduce its brittleness, and make the round steel have good comprehensive mechanical properties.

[0014] 2. The overall quenching and tempering heat treatment method of round steel improves the uniformity of the round steel's structure, optimizes the furnace loading method and heating process, ensures uniform temperature distribution of the round steel during the heating process, reduces structural inhomogeneity, and uniformly cools the steel, avoiding structural differences caused by differences in cooling rates, making the overall structure of the round steel more uniform and the performance more stable.

[0015] 3. The overall quenching and tempering heat treatment method of round steel improves production efficiency and product quality stability, precise process parameter control and stable equipment operation, reduces waste and defective products caused by process fluctuations, and improves product qualification rate. Standardized operating procedures and reasonable process arrangements shorten the heat treatment cycle, improve production efficiency, reduce production costs, and expand the application range of round steel. The performance of round steel after improved quenching and tempering heat treatment is significantly improved, and it can meet more complex working conditions and high-performance application scenarios, such as high-strength mechanical parts, heavy-loaded transmission shafts and other fields, further expanding the application range of round steel. DETAILED DESCRIPTION

[0016] 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 creative work are within the scope of protection of the present invention.

[0017] A method for overall quenching and tempering of round steel includes the following specific steps: S1 material preparation: selecting round steel of suitable specifications and materials, and ensuring that the surface of the round steel is clean and free of oil stains, rust and other impurities; S2 Equipment inspection: Check the heat treatment furnace (such as box-type resistance furnace, pit-type resistance furnace), temperature control instrument, thermocouple, quenching water tank or oil tank equipment to ensure its normal operation and reliable accuracy; S3 Preparation of fixtures: Prepare appropriate fixtures according to the size and shape of the round steel to ensure uniform heating and cooling of the round steel during heat treatment; S4 Furnace loading: Place the round steel evenly in the effective heating area of ​​the heat treatment furnace. Note that a certain distance should be maintained between the round steels to ensure uniform heat transfer. For round steels with smaller diameters, they can be loaded into the furnace by hanging; for round steels with larger diameters, they can be loaded into the furnace by laying flat; S5 Heating: According to the material of the round steel and the required quenching temperature, set the heating temperature and heating rate of the heat treatment furnace. Generally speaking, the quenching heating temperature is between 800-900℃, and the heating rate is controlled at about 5-10℃ / min. When the furnace temperature reaches the set temperature, keep it warm for a certain period of time to make the round steel fully austenitized. The holding time is determined according to the diameter and material of the round steel, usually 1-3h / 100mm diameter; S6 quenching: After the insulation is completed, the round steel is quickly taken out of the heat treatment furnace and placed in a quenching medium (such as water or oil) for quenching. During quenching, the round steel must be quickly cooled in the quenching medium to obtain a martensitic structure. For water quenching, the round steel must be continuously moved after entering the water to ensure uniform cooling; for oil quenching, the oil must be properly stirred after the round steel enters the oil to increase the cooling rate. The quenching cooling time is determined according to the diameter and material of the round steel, usually 3 - 10min / 100mm diameter; S3 furnace loading: place the quenched round steel evenly in the effective heating zone of the heat treatment furnace, and pay attention to keeping a certain distance between the round steels to ensure uniform heat transfer; Among them, S5 heating: according to the material of the round steel and the required tempering temperature, set the heating temperature and heating rate of the heat treatment furnace. Generally speaking, the tempering heating temperature is between 500-650℃, and the heating rate is controlled at about 5-10℃ / min. When the furnace temperature reaches the set temperature, keep it warm for a certain time to make the martensite in the round steel fully decompose and transform. The holding time is determined according to the diameter and material of the round steel, usually 2-5h / 100mm diameter; S7 Cooling after furnace exit: After the heat preservation is completed, the round steel is taken out of the heat treatment furnace and naturally cooled to room temperature in the air. S8 inspection: Check the surface of the round steel, which should be free of cracks, deformation, oxidation and decarburization defects; The S8 inspection also includes hardness test: use a hardness tester to test the hardness of the round steel. The hardness value should meet the design requirements. Generally speaking, the hardness of the round steel after quenching and tempering is between 22 and 32 HRC. The S8 inspection also includes metallographic examination: metallographic examination is performed on the round steel to observe its organizational morphology. The tempered bainite structure should be obtained, and the structure should be uniform and free of abnormal structure.

[0018] Furthermore, the scheme improves the comprehensive mechanical properties of the round steel. By precisely controlling the quenching heating temperature, holding time and cooling rate, the round steel surface obtains a high-hardness martensitic structure while the core maintains a certain toughness, thereby improving the strength and toughness of the round steel. Reasonable high-temperature tempering process can fully decompose and transform the quenched martensite to form tempered troostite structure, improve the plasticity and toughness of the round steel, reduce its brittleness, and make the round steel have good comprehensive mechanical properties.

[0019] This solution improves the uniformity of the round steel's structure, optimizes the furnace loading method and heating process, ensures uniform temperature distribution of the round steel during the heating process, reduces structural unevenness, and uniformly cools the steel, avoiding structural differences caused by differences in cooling rates, making the overall structure of the round steel more uniform and the performance more stable.

[0020] This solution improves production efficiency and product quality stability, precise process parameter control and stable equipment operation, reduces waste and defective products caused by process fluctuations, improves product qualification rate, standardizes operating procedures and reasonable process arrangements, shortens heat treatment cycle, improves production efficiency, reduces production costs, and expands the application range of round steel. The performance of round steel after improved quenching and tempering heat treatment is significantly improved, and it can meet more complex working conditions and high-performance application scenarios, such as high-strength mechanical parts, heavy-loaded transmission shafts and other fields, further expanding the application range of round steel.

[0021] 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 method for overall quenching and tempering heat treatment of round steel, characterized in that: It includes the following specific steps: S1 Material preparation: Select round steel of appropriate specifications and materials, and ensure that the surface of the round steel is clean, free of oil, rust and other impurities; S2 Equipment inspection: Check the heat treatment furnace (such as box-type resistance furnace, pit-type resistance furnace), temperature control instrument, thermocouple, quenching water tank or oil tank equipment to ensure its normal operation and reliable accuracy; S3 Preparation of fixtures: Prepare appropriate fixtures according to the size and shape of the round steel to ensure uniform heating and cooling of the round steel during heat treatment; S4 Furnace loading: Place the round steel evenly in the effective heating area of ​​the heat treatment furnace. Note that a certain distance should be maintained between the round steels to ensure uniform heat transfer. For round steels with smaller diameters, they can be loaded into the furnace by hanging; for round steels with larger diameters, they can be loaded into the furnace by laying flat; S5 Heating: According to the material of the round steel and the required quenching temperature, set the heating temperature and heating rate of the heat treatment furnace. When the furnace temperature reaches the set temperature, keep it warm for a certain period of time to make the round steel fully austenitized; S6 quenching: After the insulation is completed, the round steel is quickly taken out of the heat treatment furnace and placed in a quenching medium (such as water or oil) for quenching. During quenching, it is necessary to ensure that the round steel is quickly cooled in the quenching medium to obtain a martensitic structure. For water quenching, the round steel should be continuously moved after entering the water to ensure uniform cooling; for oil quenching, the oil should be properly stirred after the round steel enters the oil to increase the cooling rate; S7 Cooling after leaving the furnace: After the heat preservation is completed, the round steel is taken out of the heat treatment furnace and naturally cooled to room temperature in the air; S8 Inspection: Check the surface of the round steel, which should be free of cracks, deformation, oxidation and decarburization defects.

2. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S3 furnace loading: place the quenched round steel evenly in the effective heating zone of the heat treatment furnace. Note that a certain distance should be maintained between the round steels to ensure uniform heat transfer.

3. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S5 heating: according to the material of the round steel and the required tempering temperature, set the heating temperature and heating rate of the heat treatment furnace. Generally speaking, the tempering heating temperature is between 500-650℃, and the heating rate is controlled at about 5-10℃ / min. When the furnace temperature reaches the set temperature, keep it warm for a certain time to make the martensite in the round steel fully decompose and transform. The holding time is determined according to the diameter and material of the round steel, usually 2-5h / 100mm diameter.

4. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S8 inspection also includes a hardness test: a hardness test is performed on the round steel using a hardness tester. The hardness value should meet the design requirements. Generally speaking, the hardness of the round steel after quenching and tempering is between 22 and 32 HRC.

5. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S8 inspection also includes metallographic inspection: metallographic inspection is performed on the round steel to observe its organizational morphology. A tempered troostite structure should be obtained, and the structure should be uniform and free of abnormal structure.

6. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S6 quenching: the quenching cooling time is determined according to the diameter and material of the round steel, usually 3 - 10min / 100mm diameter.

7. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S5 heating: holding time is determined according to the diameter and material of the round steel, usually 1 - 3h / 100mm diameter.

8. The method for overall quenching and tempering of round steel according to claim 1, characterized in that: The S5 heating: the quenching heating temperature is between 800 - 900°C, and the heating rate is controlled at about 5 - 10°C / min.