CN114350904A - Normalizing heat treatment process for 30CrNi2MoVA forged piece - Google Patents
Normalizing heat treatment process for 30CrNi2MoVA forged piece Download PDFInfo
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- CN114350904A CN114350904A CN202111666244.XA CN202111666244A CN114350904A CN 114350904 A CN114350904 A CN 114350904A CN 202111666244 A CN202111666244 A CN 202111666244A CN 114350904 A CN114350904 A CN 114350904A
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Abstract
The invention discloses a normalizing heat treatment process for a 30CrNi2MoVA forged piece, which comprises the following steps: step 1, slowly cooling a forging stock to a temperature above 250 ℃, putting the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating; step 2, heating the hot charging furnace to 640-660 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the temperature of the forging stock in the hot charging furnace for 1.8-2.2 h; step 3, rapidly heating the hot charging furnace in the step 2 to 850-; step 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and after the forging stock is taken out of the furnace, cooling the forging stock by air cooling; according to the invention, after the 30CrNi2MoVA forging stock is slowly cooled after forging, two-stage heating is adopted, and the temperature is kept for a long time at 860 ℃, so that the internal forging stress and the tissue stress are eliminated, the internal stress of the forging stock is released, and the crystal grains are refined; eliminates the widmannstatten structure and the banded structure, obtains fine and uniform structure, improves the mechanical property of the forging and makes tissue preparation for subsequent heat treatment.
Description
Technical Field
The invention relates to the technical field of forging, in particular to a normalizing heat treatment process for a 30CrNi2MoVA forge piece.
Background
The 30CrNi2MoVA belongs to low alloy steel, is vanadium-containing low alloy high-strength steel, is suitable for manufacturing parts with small section thickness used after high-temperature tempering, and is also commonly used for manufacturing high-strength components with the section thickness less than 50 mm. 30CrNi2MoVA is a low-alloy high-strength alloy structural steel and is often used for manufacturing pump valves of fracturing machines in the petroleum industry.
The 30CrNi2MoVA needs high strength and toughness in performance, easily forms a widmannstatten structure due to high temperature and improper hot processing in actual production, and presents stronger grain boundary inheritance and grain inheritance in the subsequent heat treatment process, thereby causing the reduction of mechanical properties.
Therefore, after forging, the 30CrNi2MoVA needs to be slowly cooled to more than 250 ℃, is heated and charged, and is kept at 860 ℃ for a long time to eliminate internal forging stress and structural stress and prepare for subsequent heat treatment
Disclosure of Invention
The invention mainly aims to provide a normalizing heat treatment process for a 30CrNi2MoVA forging, which can effectively solve the problems of complex structure, low building efficiency, weak wind impact resistance, firmness, instability and short service life of the existing vegetable greenhouse in the background art.
In order to achieve the purpose, the invention adopts the technical scheme that: a normalizing heat treatment process for a 30CrNi2MoVA forging comprises the following steps:
step 1, slowly cooling a forging stock to a temperature above 250 ℃, putting the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating;
step 2, heating the hot charging furnace to 640-660 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the temperature of the forging stock in the hot charging furnace for 1.8-2.2 h;
step 3, rapidly heating the hot charging furnace in the step 2 to 850-;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
Preferably, the forging stock in the step 1 is naturally placed and cooled.
Preferably, in the step 2, the temperature of the hot charging furnace is raised to 650 ℃ at a heating speed of less than or equal to 150 ℃/h, and the temperature is kept for 2 h.
Preferably, in the step 3, the temperature of the hot charging furnace is increased to 860 ℃ at a heating speed of more than or equal to 10 ℃/min, and the temperature is kept for 7.5 hours.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, after the 30CrNi2MoVA forging stock is slowly cooled after forging, two-stage heating is adopted, and the temperature is kept for a long time at 860 ℃, so that the internal forging stress and the tissue stress are eliminated, the internal stress of the forging stock is released, and the crystal grains are refined; and normalizing before quenching or quenching and tempering treatment, so that the widmannstatten structure and the banded structure are eliminated, fine and uniform structures are obtained, the mechanical property of the forging is improved, and the structure preparation is made for subsequent heat treatment.
Drawings
FIG. 1 is a temperature-raising process diagram of normalizing heat treatment according to the invention.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Example 1
As shown in the attached figure 1, the normalizing heat treatment process of the 30CrNi2MoVA forged piece comprises the following steps:
step 1, slowly cooling a forged forging stock to be more than 250 ℃, then placing the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating, wherein the slow cooling mode adopts natural placement cooling;
step 2, heating the hot charging furnace to 650 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the temperature of the forging stock in the hot charging furnace for 2h to prevent the forging stock from generating cracks due to rapid heating caused by uneven material temperature;
step 3, heating the hot charging furnace in the step 2 to 860 ℃ at a temperature of more than or equal to 10 ℃/min, and preserving the heat of the forging stock in the hot charging furnace for 7.5 hours;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
Example 2
A normalizing heat treatment process for a 30CrNi2MoVA forging comprises the following steps:
step 1, slowly cooling a forged forging stock to be more than 250 ℃, then placing the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating, wherein the slow cooling mode adopts natural placement cooling;
step 2, heating the hot charging furnace to 640 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the heat of the forging stock in the hot charging furnace for 2.2h to prevent the forging stock from generating cracks due to rapid heating caused by uneven material temperature;
step 3, heating the hot charging furnace in the step 2 to 850 ℃ at a speed of more than or equal to 10 ℃/min, and preserving the heat of the forging stock in the hot charging furnace for 8 hours;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
Example 3
A normalizing heat treatment process for a 30CrNi2MoVA forging comprises the following steps:
step 1, slowly cooling a forged forging stock to be more than 250 ℃, then placing the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating, wherein the slow cooling mode adopts natural placement cooling;
step 2, heating the hot charging furnace to 660 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the temperature of the forging stock in the hot charging furnace for 1.8h to prevent the forging stock from generating cracks due to rapid heating caused by uneven material temperature;
step 3, heating the hot charging furnace in the step 2 to 870 ℃ at a temperature of more than or equal to 10 ℃/min, and preserving the temperature of the forging stock in the hot charging furnace for 7 hours;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
Example 4
A normalizing heat treatment process for a 30CrNi2MoVA forging comprises the following steps:
step 1, slowly cooling a forged forging stock to be more than 250 ℃, then placing the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating, wherein the slow cooling mode adopts natural placement cooling;
step 2, heating the hot charging furnace to 655 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the heat of the forging stock in the hot charging furnace for 1.9h to prevent the forging stock from generating cracks due to rapid heating caused by uneven material temperature;
step 3, heating the hot charging furnace in the step 2 to 865 ℃ at a speed of more than or equal to 10 ℃/min, and preserving the heat of the forging stock in the hot charging furnace for 7.2 hours;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
Example 5
A normalizing heat treatment process for a 30CrNi2MoVA forging comprises the following steps:
step 1, slowly cooling a forged forging stock to be more than 250 ℃, then placing the forging stock into a hot charging furnace, and keeping a gap between the forging stock and the forging stock to ensure uniform heating, wherein the slow cooling mode adopts natural placement cooling;
step 2, heating the hot charging furnace to 645 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the heat of the forging stock in the hot charging furnace for 2.1h to prevent the forging stock from generating cracks due to rapid heating caused by uneven material temperature;
step 3, heating the hot charging furnace in the step 2 to 855 ℃ at a temperature of more than or equal to 10 ℃/min, and preserving the heat of the forging stock in the hot charging furnace for 7.8 hours;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
In the five examples described above, the heat-retention time can be appropriately shortened when no hardness is required as the preliminary heat treatment.
Data analysis is carried out on the five embodiments, and finally, the test shows that after the forging of the 30CrNi2MoVA forging stock, the forging stock is slowly cooled, two-stage heating is adopted, and the temperature is kept at 860 ℃ for a long time, so that the internal forging stress and the structure stress are eliminated, the internal stress of the forging stock is released, and the crystal grains are refined; and normalizing before quenching or quenching and tempering treatment, so that the widmannstatten structure and the banded structure are eliminated, fine and uniform structures are obtained, the mechanical property of the forging is improved, and the structure preparation is made for subsequent heat treatment.
While certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that the described embodiments may be modified in various different ways without departing from the spirit and scope of the invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.
Claims (4)
1. A normalizing heat treatment process for a 30CrNi2MoVA forging is characterized by comprising the following steps: the method comprises the following steps:
step 1, slowly cooling the forging stock to more than 250 ℃, putting the forging stock into a hot charging furnace,
step 2, heating the hot charging furnace to 640-660 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving the temperature of the forging stock in the hot charging furnace for 1.8-2.2 h;
step 3, rapidly heating the hot charging furnace in the step 2 to 850-;
and 4, after the forging stock in the step 3 is uniformly and thoroughly heated, turning off a power supply, and discharging and then cooling by air cooling.
2. The normalizing heat treatment process for the 30CrNi2MoVA forging according to claim 1, wherein the normalizing heat treatment process comprises the following steps: and naturally placing and cooling the forging stock in the step 1.
3. The normalizing heat treatment process for the 30CrNi2MoVA forging according to claim 1, wherein the normalizing heat treatment process comprises the following steps: and (3) heating the hot charging furnace in the step (2) to 650 ℃ at a heating speed of less than or equal to 150 ℃/h, and preserving heat for 2 h.
4. The normalizing heat treatment process for the 30CrNi2MoVA forging according to claim 1, wherein the normalizing heat treatment process comprises the following steps: and in the step 3, the temperature of the hot charging furnace is increased to 860 ℃ at the heating speed of more than or equal to 10 ℃/min, and the heat is preserved for 7.5 hours.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101906518A (en) * | 2010-08-20 | 2010-12-08 | 张家港市广大机械锻造有限公司 | Post-forging heat treatment process for nickeliferous dilute alloy round steel |
| CN103305673A (en) * | 2013-07-01 | 2013-09-18 | 江阴市恒业锻造有限公司 | Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock |
| CN111151695A (en) * | 2019-12-31 | 2020-05-15 | 太原重工股份有限公司 | Forging heat treatment process of valve rod for steam turbine with material of 30Cr2Ni4MoV |
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2021
- 2021-12-31 CN CN202111666244.XA patent/CN114350904A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101906518A (en) * | 2010-08-20 | 2010-12-08 | 张家港市广大机械锻造有限公司 | Post-forging heat treatment process for nickeliferous dilute alloy round steel |
| CN103305673A (en) * | 2013-07-01 | 2013-09-18 | 江阴市恒业锻造有限公司 | Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock |
| CN111151695A (en) * | 2019-12-31 | 2020-05-15 | 太原重工股份有限公司 | Forging heat treatment process of valve rod for steam turbine with material of 30Cr2Ni4MoV |
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