CN114774644A - ADI surface quenching process - Google Patents
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- CN114774644A CN114774644A CN202210426563.1A CN202210426563A CN114774644A CN 114774644 A CN114774644 A CN 114774644A CN 202210426563 A CN202210426563 A CN 202210426563A CN 114774644 A CN114774644 A CN 114774644A
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- 238000010791 quenching Methods 0.000 title claims abstract description 69
- 230000000171 quenching effect Effects 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 28
- 230000008569 process Effects 0.000 title claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 64
- 230000006698 induction Effects 0.000 claims abstract description 35
- 239000000463 material Substances 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims description 26
- 239000002344 surface layer Substances 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 238000009423 ventilation Methods 0.000 claims description 8
- 238000005507 spraying Methods 0.000 claims description 5
- 229910001566 austenite Inorganic materials 0.000 description 18
- 229910000734 martensite Inorganic materials 0.000 description 17
- 239000010410 layer Substances 0.000 description 14
- 239000011159 matrix material Substances 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 11
- 229910000859 α-Fe Inorganic materials 0.000 description 11
- 230000007704 transition Effects 0.000 description 10
- 230000035882 stress Effects 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 230000036961 partial effect Effects 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 229910001141 Ductile iron Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910001563 bainite Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002500 effect on skin Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
- C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
- C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D5/00—Heat treatments of cast-iron
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention belongs to the technical field of materials, and particularly relates to an ADI surface quenching process, which is used for carrying out heat treatment on an ADI workpiece in advance and then carrying out surface quenching in an induction heating mode to obtain an ADI material with high plasticity and high toughness at the core part and high hardness and high wear resistance at the surface.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to an ADI surface quenching process.
Background
Austempered Ductile Iron (ADI) is a novel engineering material obtained by carrying out isothermal quenching on the basis of ductile iron, the matrix structure of the ADI is acicular ferrite and high-carbon austenite (namely ferrite), the ADI is also called ausferrite ductile iron, and because of the unique ausferrite structure, the ADI has excellent mechanical properties, is a novel high-performance engineering material, and is a novel engineering material which is suitable for manufacturing key parts of high-end equipment and is lightweight, innovative and highly competitive in the field of steel materials.
ADI the better the plasticity and toughness, the poorer the hardness and wear resistance; conversely, the higher the hardness and wear resistance, the lower the plasticity and toughness. It is difficult to meet the requirements for applications where high plasticity, high toughness and high wear resistance of the surface are desired. If on the basis of ADI with high plasticity and high toughness, a proper subsequent surface heat treatment process is adopted, and the surface hardness and the wear resistance are greatly improved while the plasticity and the toughness of the internal matrix are kept unchanged, the application range of ADI can be further enlarged undoubtedly, and the service life is prolonged.
The surface quenching is a surface heat treatment process for rapidly heating the surface layer of the steel material to austenize and then rapidly cooling to change the surface structure of the steel material into martensite. On the premise of ensuring that the core structure of the workpiece is not changed, the surface hardness and the wear resistance of the steel workpiece are improved through the phase change of the surface structure. The microstructure of ADI consists of a matrix of high-carbon austenite + acicular ferrite and spheroidal graphite, the austenite (Ausferrite) structure formed by the high-carbon austenite + acicular ferrite is different from the bainite in steel, no carbide is precipitated at the grain boundary of the acicular ferrite, and the bainite in steel is characterized by ferrite and precipitated carbide. By means of surface quenching, the surface hardness and the wear resistance of the ADI core are further improved on the premise of ensuring high plasticity and high toughness of the ADI core, so that the ADI material has a high-strength and high-wear-resistance surface, and the ADI core still has good plasticity and toughness.
However, in practice, ADI surface quenching is very likely to cause quench cracking, and an ADI material having high plasticity and high toughness in the core and high hardness and high wear resistance in the surface cannot be obtained, so that there is a need for an improved ADI surface quenching process.
Disclosure of Invention
In order to solve the problems, the invention provides an ADI surface quenching process for ADI materials with higher plasticity and toughness, such as QTD800-10, QTD900-8, QTD1050-6 and the like, so that the ADI materials have good plasticity and toughness in the core part and high hardness and high wear resistance on the surface. The specific method comprises the following steps: the ADI workpiece is subjected to pre-heat treatment and then surface quenching in an induction heating mode to obtain the ADI material with high plasticity and high toughness at the core part and high hardness and high wear resistance at the surface.
The method comprises the following specific steps: step 1, pre-heat treatment: placing the workpiece on a workbench of induction heating equipment, aligning the surface of the ADI workpiece to be processed, performing induction heating for 3-8s, stopping heating, and immediately performing ventilation cooling on the heating surface layer;
step 2, surface quenching: and (3) placing the workpiece on a workbench of induction heating equipment, aligning the workpiece to the surface of the ADI workpiece to be quenched, performing induction heating for 3-6s, stopping heating, and immediately performing water spraying cooling.
Wherein, in the preheating treatment in the step 1 and the surface quenching in the step 2, the parameters of the induction heating equipment are as follows; the current density is 50A/mm2The current frequency was 68 KHz.
Wherein, the time for ventilation cooling in the preheating treatment in the step 1 is 30-50s, and the time for water spraying cooling in the surface quenching in the step 2 is 7-12 s.
Compared with the prior art, the invention has the beneficial effects that: (1) the two-step heat treatment method of pre-heat treatment and surface quenching is adopted, so that cracks of a transition layer can be avoided during surface quenching, cracking can be prevented, and the surface structure can be refined; (2) after the process is adopted for treatment, the surface matrix structure of the ADI is changed into a fine acicular martensite structure from an austenite structure, so that the surface hardness and the wear resistance of the ADI are greatly improved, the original iron body structure is still reserved in the core, the ADI has good plasticity and toughness, and the surface hardness and the wear resistance of the ADI can be greatly improved on the premise of ensuring the high toughness and the high plasticity of the core; (3) in the preheating treatment of step 1: after the induction heating time is 3-8s, stopping heating and immediately carrying out ventilation cooling on the heating surface layer for 30-50s, wherein the reason for adopting ventilation cooling is to improve the cooling speed, refine surface layer crystal grains, make the structure more uniform and avoid cracks and fissures generated during the surface quenching in the step 2; in step 2 surface quench: the water spray cooling which can further accelerate the cooling speed is adopted, and the water spray cooling can be directly carried out on the workpiece, so that the phenomenon that the time for taking out, transferring and cooling the workpiece is prolonged to influence the surface quenching quality is avoided, a martensite structure with fine crystal grains can be obtained, and the surface hardness and the wear resistance are greatly improved; (4) the process is clean, environment-friendly, energy-saving and efficient.
Detailed Description
The principle explanation of the invention and the effect analysis of the scheme are as follows:
feasibility analysis of ADI surface quenching
The surface quenching of induction heating is carried out on the ADI workpiece, the heat effect caused by the eddy current generated by the induction coil heats the surface of the ADI workpiece to the quenching temperature, because of the skin effect, the eddy current of the section of the ADI workpiece is not uniformly distributed, the eddy current strength of the surface of the ADI workpiece is the highest, the eddy current strength is smaller and is attenuated by an exponential law closer to the core, and therefore the surface layer of the ADI workpiece can be rapidly heated without affecting the core tissue.
The matrix of ADI is austenite, ferrite in the ADI matrix structure is very fine, so a large number of grain boundaries exist, austenite in the matrix is fully reacted stable high-carbon austenite, and the supersaturated interstitial solid solution can cause austenite lattice distortion to form a distortion stress field. The yield strength and tensile strength of ADI are higher than those of ordinary cast iron. The plasticity and toughness of ADI are derived from the block austenite between the acicular ferrites, and the higher the number of the block austenite, the better the plasticity and toughness.
Second, structural hierarchy analysis of the material obtained by ADI surface quenching
The ADI surface induction quenching has high heating speed, so that the superheat degree is high during phase change, a large number of fine austenite grains can be formed on an austenite and ferrite interface, and after the temperature is rapidly reduced, cryptomorphic martensite can be generated. At the same time, rapid heating makes the carbon element have no time to diffuse, so that the generated super-cooled austenite has poor stability. After austenite quenching with different components, the carbon content of the generated martensite is greatly different, and high-carbon martensite and low-carbon martensite coexist in the quenched structure. After the ADI workpiece is subjected to induction heating surface quenching, the interface of the ADI workpiece can be divided into a central area, a transition area (partial phase change) and a hardening layer from inside to outside.
A central region: in the induction heating quenching of the partial region, the temperature does not reach the lower critical temperature, austenite transformation does not occur, and the matrix structure is still an austenitic structure, so that the performance is not changed.
And in the transition zone (partial phase transformation), the temperature is between the lower critical temperature and the upper critical temperature during induction heating quenching, partial matrix is austenitized, and the matrix structure after quenching is a mixed structure consisting of ferrite, troostite and martensite. Meanwhile, the ferrite content increases as the temperature decreases.
Hardening layer: the temperature of the partial area exceeds the upper critical temperature in the induction hardening process, but the temperature gradient still exists. The temperature close to the surface is higher, the austenitization is sufficient, and an acicular martensite structure with uniform carbon content is formed after quenching; the farther away from the surface layer, the less the carbon element in the austenite structure diffuses, and the needle-like martensite structure with non-uniform carbon content is obtained after quenching.
Thirdly, ADI surface quenching easily causes quenching cracks
And carrying out surface quenching on the ADI workpiece obtained after the isothermal quenching treatment by using a penetration induction heating method, wherein the penetration depth of the current passing through an induction coil on the surface of the ADI workpiece is more than the required depth of a hardening layer. The penetration type induction heating mode is high in heating speed, energy-saving and environment-friendly, and due to the fact that the heating speed is high, the time is short, heat is concentrated on the surface of the ADI workpiece, and a martensitic structure can be obtained through rapidly cooling the surface layer. Meanwhile, the heat conduction of the core part is very small, so that the core part of the ADI workpiece can keep the original matrix structure unchanged. However, induction quenching has a fast heating speed, a large temperature gradient, and uneven temperature distribution at each part, and cracks are easily formed in the transition region between the hardened layer and the core due to the combined action of thermal stress and structural stress during quenching cooling.
Method and principle for solving quenching cracks
Before the ADI is subjected to surface quenching, a preheating treatment is carried out to refine the uniform structure so as to avoid cracks in a transition region during surface quenching and prevent cracking.
The reason that the pre-heat treatment can effectively prevent the generation of the quenching cracks of the transition layer is that in the surface quenching process, the cracks of the transition region are mainly caused by the fact that the internal temperature and the structure of a workpiece are not uniform, and large thermal stress and structural stress are generated. The main reason for stress generated during surface quenching of ADI workpiece is uneven heating of surface layer and core. Before surface quenching, surface pre-heat treatment is carried out to ensure that the surface layer obtains fine and dispersed sorbite tissues, and then induction heating surface quenching is carried out, so that austenite can be homogenized in a short time in the induction heating quenching process, and quenching cracks in a surface quenching transition region are avoided. Meanwhile, penetration type induction heating is adopted, so that the workpiece has a gentle hardness gradient and strength gradient on a transition layer, and the occurrence of quenching cracks can be further avoided.
When the induction heating surface quenching is subjected to martensite phase transformation, the martensite generated by the hardening layer expands in volume, but the center of the induction heating surface quenching does not undergo martensite phase transformation, so that the expansion of the martensite of the hardening layer is restricted, so that compressive stress can be formed on the hardening layer, and when the hardening layer is subjected to the compressive stress, the atoms of the hardening layer tend to be mutually compressed, thereby being beneficial to preventing the generation of quenching cracks. The compressive stress is also beneficial to improving the hardness and the wear resistance of the hardening layer of the workpiece.
Fifthly, the optimal process adopted by the invention
The surface hardening of ADI is carried out in two steps. Step 1, pre-heat treatment: and (3) placing the workpiece on a workbench of induction heating equipment, aligning the coil to the ADI surface to be processed, and turning on a power supply after checking that no fault exists. Adjusting the treatment process parameters on the equipment to be; the current density is 50A/mm2Stopping heating and immediately ventilating and cooling the heating surface layer for 30-50s after the current frequency is 68KHz and the induction heating time is 3-8 s; surface quenching in step 2: and (3) placing the workpiece on a workbench of induction heating equipment, aligning the coil to the ADI surface to be quenched, and turning on a power supply after checking that no fault exists. Adjusting the quenching technological parameters on the equipment to be; the current density is 50A/mm2And the current frequency is 68KHz, after the induction heating time is 3-6s, the heating is stopped, and the water spraying cooling is immediately carried out for 7-12 s.
Sixthly, effect analysis of the process
(1) The two-step heat treatment method of pre-heat treatment and surface quenching is adopted, so that cracks of the transition layer can be avoided during surface quenching, and cracking can be prevented.
(2) After the ADI surface layer matrix structure is treated by the process, the ausferrite is converted into the acicular martensite, so that the surface hardness and the wear resistance of the ADI are greatly improved, the original iron body structure is still reserved in the core, the ADI surface layer matrix structure has good plasticity and toughness, and the surface hardness and the wear resistance of the ADI surface layer matrix structure can be greatly improved on the premise of ensuring the high plasticity and the high toughness of the ADI core.
(3) In the preheating treatment of step 1: after the induction heating time is 3-8s, stopping heating and immediately carrying out ventilation cooling on the heating surface layer for 30-50s, wherein the reason for adopting ventilation cooling is to improve the cooling speed, refine surface layer crystal grains, make the structure more uniform and avoid cracks and fissures generated during the surface quenching in the step 2; in step 2 surface quench: the water spray cooling which can further accelerate the cooling speed is adopted, and the water spray cooling can be directly carried out on the workpiece, so that the influence on the surface quenching quality caused by the time prolonging caused by the complicated operations of taking out, transferring and recooling the workpiece is avoided, a martensite structure with fine crystal grains can be obtained, and the surface hardness and the wear resistance are greatly improved.
(4) The process is clean, environment-friendly, energy-saving and efficient.
Claims (4)
1. An ADI surface quenching process, which is characterized in that: the ADI workpiece is subjected to pre-heat treatment and then surface quenching in an induction heating mode to obtain the ADI material with high plasticity and high toughness at the core part and high hardness and high wear resistance at the surface.
2. The ADI surface quenching process of claim 1, comprising the steps of:
step 1, heat treatment in advance: placing the workpiece on a workbench of induction heating equipment, aligning the surface of the ADI workpiece to be processed, performing induction heating for 3-8s, stopping heating, and immediately performing ventilation cooling on the heating surface layer;
step 2, surface quenching: and (3) placing the workpiece on a workbench of induction heating equipment, aligning the workpiece to the surface of the ADI workpiece to be quenched, performing induction heating for 3-6s, stopping heating, and immediately performing water spraying cooling.
3. The ADI surface quenching process of claim 2, characterized in that: in the steps of 1, preheating and 2, surface quenching, parameters of induction heating equipment are as follows; the current density is 50A/mm2The current frequency is 68 KHz.
4. The ADI surface quenching process of claim 2, characterized in that: the time for ventilation cooling in the preheating treatment in the step 1 is 30-50s, and the time for water spraying cooling in the surface quenching in the step 2 is 7-12 s.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210426563.1A CN114774644A (en) | 2022-04-21 | 2022-04-21 | ADI surface quenching process |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210426563.1A CN114774644A (en) | 2022-04-21 | 2022-04-21 | ADI surface quenching process |
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| CN114774644A true CN114774644A (en) | 2022-07-22 |
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| CN202210426563.1A Pending CN114774644A (en) | 2022-04-21 | 2022-04-21 | ADI surface quenching process |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4905538A (en) * | 1988-01-25 | 1990-03-06 | Nissan Motor Co., Ltd. | Camshaft |
| CN101348878A (en) * | 2008-08-26 | 2009-01-21 | 朱志文 | Isothermal quench bainitic ductile cast iron and use thereof |
| CN112080625A (en) * | 2020-09-25 | 2020-12-15 | 马鞍山钢铁股份有限公司 | High-speed rail axle surface induction quenching process with speed per hour being more than or equal to 400 kilometers, high-speed rail axle and production method thereof |
-
2022
- 2022-04-21 CN CN202210426563.1A patent/CN114774644A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4905538A (en) * | 1988-01-25 | 1990-03-06 | Nissan Motor Co., Ltd. | Camshaft |
| CN101348878A (en) * | 2008-08-26 | 2009-01-21 | 朱志文 | Isothermal quench bainitic ductile cast iron and use thereof |
| CN112080625A (en) * | 2020-09-25 | 2020-12-15 | 马鞍山钢铁股份有限公司 | High-speed rail axle surface induction quenching process with speed per hour being more than or equal to 400 kilometers, high-speed rail axle and production method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 刘海明: "等温淬火球墨铸铁(ADI)的新型热处理研究", 《中国优秀硕士学位论文全文数据库（工程科技I辑）》, no. 9, pages 022 - 38 * |
| 李冲: "表面淬火对ADI组织与性能影响及数值模拟的研究", 《中国优秀硕士学位论文全文数据库（工程科技I辑）, no. 8, pages 022 - 84 * |
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