CN110904313A - Box type natural gas spheroidizing annealing process - Google Patents
Box type natural gas spheroidizing annealing process Download PDFInfo
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- CN110904313A CN110904313A CN201811087247.6A CN201811087247A CN110904313A CN 110904313 A CN110904313 A CN 110904313A CN 201811087247 A CN201811087247 A CN 201811087247A CN 110904313 A CN110904313 A CN 110904313A
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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
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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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
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
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- Crystallography & Structural Chemistry (AREA)
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- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
Abstract
The invention provides a box-type natural gas spheroidizing annealing process, which comprises the following steps: (1) placing the workpiece in a vacuum annealing furnace, and vacuumizing to 1 atm; (2) introducing high-purity nitrogen as carrier gas, repressing the annealing furnace, carrying out first-stage temperature rise in the furnace, vacuumizing, and carrying out first heat preservation, (3) carrying out second-stage temperature rise on the temperature in the furnace after the first heat preservation is finished, and carrying out second heat preservation; (4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace, and carrying out third heat preservation; (5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then changing a cooling cover to cool to 290-310 ℃, finally draining water to cool to 80 ℃, and cooling at a cooling rate of 2.2-2.3 ℃/s; (6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
Description
Technical Field
The invention relates to the technical field of workpiece heat treatment, in particular to a box-type natural gas spheroidizing annealing process.
Background
In order to enable the workpiece to have required mechanical properties, physical properties and chemical properties, besides reasonable selection of materials and forming processes, a heat treatment process is often indispensable, the shape of the workpiece is changed, the potential of the workpiece can be fully exerted through heat treatment, various required special properties are given to the workpiece, and the purposes of improving the quality of the workpiece, prolonging the service life and ensuring safe and reliable operation of a machine are achieved. And the heating temperature of spheroidizing annealing is a key factor influencing the completeness of spheroidizing. The heating temperature is properly selected, which not only can ensure that the lamellar pearlite disappears, but also can reserve a part of carbide which is not completely dissolved in austenite to be used as a spheroidizing core, and finally, a normal spheroidizing structure of coarse granular carbide is formed. When the austenitizing temperature is very high, the carbide is completely dissolved and homogenized, lamellar pearlite is always obtained after cooling, and the cooling speed directly influences the size and uniformity of carbide particles. The cooling is too fast and the carbide particles are too fine and there is no possibility of forming plate-like carbides, resulting in a higher hardness. When the cooling is too slow, the carbide particles are too coarse.
The most critical part of annealing a workpiece is the control of the temperature and the temperature rise and fall rate in the vacuum annealing furnace.
Disclosure of Invention
Therefore, one of the objectives of the present invention is to provide a box-type natural gas spheroidizing annealing process, which can effectively improve the comprehensive mechanical properties of the workpiece through precise annealing temperature and duration control.
In order to achieve the above object, the present invention provides a box-type natural gas spheroidizing annealing process, which comprises the following steps:
(1) placing the workpiece in a vacuum annealing furnace, and vacuumizing to 1 atm;
(2) introducing high-purity nitrogen as a carrier gas, repressing the annealing furnace, heating the furnace to 430-450 ℃ at the first stage, vacuumizing to 4 x 102mba vacuum degree, and performing primary heat preservation at the temperature of 430-450 ℃ for 4-5 hours;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430-450 ℃ to 600-620 ℃, and carrying out second heat preservation at the temperature of 600-620 ℃, wherein the heat preservation time is 2-3 hours;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace from 600-620 ℃ to 700-720 ℃, and carrying out third heat preservation at the temperature of 700-720 ℃ for 18-20 hours;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then changing a cooling cover to cool to 290-310 ℃, finally draining water to cool to 80 ℃, and cooling at a cooling rate of 2.2-2.3 ℃/s;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
Further, in the step (1), the high-purity nitrogen is nitrogen with the volume percentage of more than or equal to 99.99%.
Furthermore, a cooling air pipe and a fan are adopted during cooling.
Further, in the step (5), the air cooling time is 7-8 hours.
Compared with the prior art, the invention adopts a step-type heating method, can obtain better mechanical properties such as strength, shaping and the like through strict process parameter control, and the spheroidized workpiece has bright surface, no carbonization and decarburization, and the spheroidization rate of pearlite is more than or equal to 99.5 percent. In addition, the process is simple and easy to implement and high in production efficiency.
The advantages and spirit of the present invention will be further understood by the following detailed description of the invention.
Detailed Description
The invention provides a box-type natural gas spheroidizing annealing process, which comprises the following steps:
(1) placing the workpiece in a vacuum annealing furnace, wherein the atmosphere in the furnace is pure nitrogen, the content of oxygen is 0 percent, and the pressure is 65-70 mbar;
(2) heating the furnace to 430-450 ℃ in a first stage, carrying out first heat preservation at the temperature of 430-450 ℃, keeping the temperature for 4-5 hours, and simultaneously blowing and discharging smoke to improve the atmosphere in the furnace; wherein the temperature rise rate of the first-stage temperature rise is 120-;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430-450 ℃ to 600-620 ℃, and carrying out second heat preservation at the temperature of 600-620 ℃, wherein the heat preservation time is 2-3 hours; wherein the temperature rise rate of the second stage temperature rise is 60-150 ℃/h;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace from 600-620 ℃ to 700-720 ℃, and carrying out third heat preservation at the temperature of 700-720 ℃ for 18-20 hours; wherein the temperature rise rate of the third stage temperature rise is 50-100 ℃/h;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then exchanging a cooling cover to cool the air to 290-310 ℃, wherein the air cooling time is 7-8 hours, and finally, discharging water to cool the water to 80 ℃;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
Preferably, the box-type natural gas spheroidizing annealing process comprises the following steps:
(1) placing the workpiece in a vacuum annealing furnace;
(2) heating the furnace to 430 ℃ in a first stage, and carrying out first heat preservation at the temperature of 430 ℃ for 4 hours;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430 ℃ to 600 ℃, and carrying out second heat preservation at the temperature of 600 ℃, wherein the heat preservation time is 2 hours;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 600 ℃ to 700 ℃, and carrying out third heat preservation at the temperature of 700 ℃, wherein the heat preservation time is 18 hours;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then exchanging a cooling cover for air cooling to 300 ℃, and finally draining water for water cooling to 80 ℃;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
The following description will be given with reference to examples.
Example 1:
in this embodiment, the box-type natural gas spheroidizing annealing process includes the following steps:
(1) placing the workpiece in a vacuum annealing furnace, wherein the atmosphere in the furnace is pure nitrogen, the content of oxygen is 0 percent, and the pressure is 65 mbar;
(2) heating the furnace to 430 ℃ in a first stage, carrying out first heat preservation at the temperature of 430 ℃ for 4 hours, and simultaneously blowing and exhausting smoke to improve the atmosphere in the furnace; wherein the temperature rise rate of the first stage temperature rise is 120 ℃/h;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430 ℃ to 600 ℃, and carrying out second heat preservation at the temperature of 600 ℃, wherein the heat preservation time is 2 hours; wherein the temperature rise rate of the second-stage temperature rise is 60 ℃/h;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 600 ℃ to 700 ℃, and carrying out third heat preservation at the temperature of 700 ℃, wherein the heat preservation time is 18 hours; wherein the temperature rise rate of the third stage temperature rise is 50 ℃/h;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then exchanging a cooling cover for air cooling to 300 ℃, wherein the air cooling time is 7 hours, and finally, discharging water for water cooling to 80 ℃;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
In the method, the workpiece annealed by the method of the embodiment is detected, and the pearlite nodularity is more than or equal to 99.5%, and the workpiece has good mechanical properties such as strength and shaping.
Example 2:
in this embodiment, the box-type natural gas spheroidizing annealing process includes the following steps:
(1) placing the workpiece in a vacuum annealing furnace, wherein the atmosphere in the furnace is pure nitrogen, the content of oxygen is 0 percent, and the pressure is 70 mbar;
(2) heating the furnace to 450 ℃ in a first stage, carrying out first heat preservation at the temperature of 450 ℃, keeping the temperature for 5 hours, simultaneously blowing and discharging smoke, and improving the atmosphere in the furnace; wherein the temperature rise rate of the first-stage temperature rise is 200 ℃/h;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 450 ℃ to 620 ℃, and carrying out second heat preservation at the temperature of 620 ℃, wherein the heat preservation time is 3 hours; wherein the temperature rise rate of the second-stage temperature rise is 150 ℃/h;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 620 ℃ to 720 ℃, and carrying out third heat preservation at the temperature of 720 ℃ for 20 hours; wherein the temperature rise rate of the third stage temperature rise is 100 ℃/h;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then exchanging a cooling cover to cool the air to 290 ℃, wherein the air cooling time is 8 hours, and finally draining water to cool the water to 80 ℃;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
In the method, the workpiece annealed by the method of the embodiment is detected, and the pearlite nodularity is more than or equal to 99.5%, and the workpiece has good mechanical properties such as strength and shaping.
Example 3:
in this embodiment, the box-type natural gas spheroidizing annealing process includes the following steps:
(1) placing the workpiece in a vacuum annealing furnace, wherein the atmosphere in the furnace is pure nitrogen, the content of oxygen is 0 percent, and the pressure is 68 mbar;
(2) heating the furnace to 430 ℃ in a first stage, carrying out first heat preservation at the temperature of 430 ℃ for 4 hours, and simultaneously blowing and exhausting smoke to improve the atmosphere in the furnace; wherein the temperature rise rate of the first stage temperature rise is 160 ℃/h;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430 ℃ to 600 ℃, and carrying out second heat preservation at the temperature of 600 ℃, wherein the heat preservation time is 2 hours; wherein the temperature rise rate of the second-stage temperature rise is 100 ℃/h;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 600 ℃ to 700 ℃, and carrying out third heat preservation at the temperature of 700 ℃, wherein the heat preservation time is 18 hours; wherein the temperature rise rate of the third stage temperature rise is 70 ℃/h;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then exchanging a cooling cover to cool to 310 ℃, wherein the air cooling time is 7.5 hours, and finally draining water to cool to 80 ℃;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
In the method, the workpiece annealed by the method of the embodiment is detected, and the pearlite nodularity is more than or equal to 99.5%, and the workpiece has good mechanical properties such as strength and shaping.
In summary, the conventional process employs linear temperature rise, which is not favorable for uniform heating of the furnace charge, and although the strong convection gas enhances the heat transfer, the heat transfer time from the surface to the center of the furnace charge is also related to the heat absorption rate and the size of the specification of the material. Under the condition that production conditions such as furnace temperature uniformity, heating and cooling speed and the like are accurately guaranteed on equipment, the process route strictly follows three elements of an annealing process, namely heating temperature, heat preservation time and cooling speed, and the invention carries out three-time heating and three-time heat preservation and secondary heat preservation, is beneficial to uniformity during large-furnace-quantity spheroidizing annealing and provides conditions for subsequent phase change and spheroidizing; the third heat preservation time is set to be longer, and sufficient time and temperature are provided for spheroidization, so that the workpiece subjected to the annealing process can obtain better mechanical properties such as strength, shaping and the like, the spheroidized workpiece has a bright surface, is free of carbonization and decarbonization, and the spheroidization rate of pearlite is more than or equal to 99.5%. In addition, the process is simple and easy to implement and high in production efficiency.
The above detailed description of the preferred embodiments is intended to more clearly illustrate the features and spirit of the present invention, and is not intended to limit the scope of the present invention by the preferred embodiments disclosed above. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. The scope of the claims to be accorded the invention is therefore to be accorded the broadest interpretation so as to encompass all such modifications and equivalent arrangements as is known in the art.
Claims (4)
1. The box-type natural gas spheroidizing annealing process is characterized by comprising the following steps of:
(1) placing the workpiece in a vacuum annealing furnace, and vacuumizing to 1 atm;
(2) introducing high-purity nitrogen as a carrier gas, repressing the annealing furnace, heating the furnace to 430-450 ℃ at the first stage, vacuumizing to 4 x 102mba vacuum degree, and performing primary heat preservation at the temperature of 430-450 ℃ for 4-5 hours;
(3) after the first heat preservation is finished, carrying out second-stage temperature rise on the temperature in the furnace, wherein the temperature is raised from 430-450 ℃ to 600-620 ℃, and carrying out second heat preservation at the temperature of 600-620 ℃, wherein the heat preservation time is 2-3 hours;
(4) after the second heat preservation is finished, carrying out third-stage temperature rise on the temperature in the furnace from 600-620 ℃ to 700-720 ℃, and carrying out third heat preservation at the temperature of 700-720 ℃ for 18-20 hours;
(5) after the third heat preservation is finished, slowly cooling for 2 hours with a cover, then changing a cooling cover to cool to 290-310 ℃, finally draining water to cool to 80 ℃, and cooling at a cooling rate of 2.2-2.3 ℃/s;
(6) and taking the annealed workpiece out of the vacuum annealing furnace, and air-cooling the workpiece outside the furnace to room temperature.
2. The box-type natural gas spheroidizing annealing process according to claim 1, wherein in the step (1), the high-purity nitrogen gas is nitrogen gas with volume percentage of more than or equal to 99.99%.
3. The box-type natural gas spheroidizing annealing process according to claim 1, wherein a cooling air pipe and a fan are adopted during cooling.
4. The box-type natural gas spheroidizing annealing process according to claim 1, wherein in the step (5), the air cooling time is 7-8 hours.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811087247.6A CN110904313A (en) | 2018-09-18 | 2018-09-18 | Box type natural gas spheroidizing annealing process |
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| CN201811087247.6A CN110904313A (en) | 2018-09-18 | 2018-09-18 | Box type natural gas spheroidizing annealing process |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111519000A (en) * | 2020-04-27 | 2020-08-11 | 浙江丰原型钢科技有限公司 | Round steel blank spheroidizing annealing process |
| CN111944960A (en) * | 2020-07-15 | 2020-11-17 | 涟源钢铁集团有限公司 | Method for reducing spheroidizing annealing decarburization of medium-high carbon steel in hot rolling |
| CN112553420A (en) * | 2020-12-02 | 2021-03-26 | 太仓富勒姆纳米新材料科技有限公司 | Strong-convection spheroidizing annealing process for rivets for automobile bearing retainer |
| CN114875216A (en) * | 2022-05-10 | 2022-08-09 | 上海汽车变速器有限公司 | Bevel gear spheroidizing annealing process and push rod furnace |
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| CN105349766A (en) * | 2015-12-18 | 2016-02-24 | 安徽楚江科技新材料股份有限公司 | Copper strip cover-type furnace annealing technology |
| CN107090539A (en) * | 2017-06-23 | 2017-08-25 | 江苏丰东热处理及表面改性工程技术研究有限公司 | A kind of bearing steel vacuum isothermal annealing process |
| CN107502712A (en) * | 2017-09-15 | 2017-12-22 | 中天合金技术有限公司 | A kind of copper strips bell-type annealing technique |
| CN107881303A (en) * | 2017-12-30 | 2018-04-06 | 江苏创泰特钢制品有限公司 | Steel annealing process |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105349766A (en) * | 2015-12-18 | 2016-02-24 | 安徽楚江科技新材料股份有限公司 | Copper strip cover-type furnace annealing technology |
| CN107090539A (en) * | 2017-06-23 | 2017-08-25 | 江苏丰东热处理及表面改性工程技术研究有限公司 | A kind of bearing steel vacuum isothermal annealing process |
| CN107502712A (en) * | 2017-09-15 | 2017-12-22 | 中天合金技术有限公司 | A kind of copper strips bell-type annealing technique |
| CN107881303A (en) * | 2017-12-30 | 2018-04-06 | 江苏创泰特钢制品有限公司 | Steel annealing process |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111519000A (en) * | 2020-04-27 | 2020-08-11 | 浙江丰原型钢科技有限公司 | Round steel blank spheroidizing annealing process |
| CN111944960A (en) * | 2020-07-15 | 2020-11-17 | 涟源钢铁集团有限公司 | Method for reducing spheroidizing annealing decarburization of medium-high carbon steel in hot rolling |
| CN111944960B (en) * | 2020-07-15 | 2022-03-08 | 涟源钢铁集团有限公司 | Method for reducing spheroidizing annealing decarburization of medium-high carbon steel in hot rolling |
| CN112553420A (en) * | 2020-12-02 | 2021-03-26 | 太仓富勒姆纳米新材料科技有限公司 | Strong-convection spheroidizing annealing process for rivets for automobile bearing retainer |
| CN114875216A (en) * | 2022-05-10 | 2022-08-09 | 上海汽车变速器有限公司 | Bevel gear spheroidizing annealing process and push rod furnace |
| CN114875216B (en) * | 2022-05-10 | 2024-08-20 | 上海汽车变速器有限公司 | Bevel gear spheroidizing annealing process and push rod furnace |
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Application publication date: 20200324 |