CN111057824B - Increase medium carbon CrNi3Heat treatment process for grain size of Mo material forging - Google Patents
Increase medium carbon CrNi3Heat treatment process for grain size of Mo material forging Download PDFInfo
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- CN111057824B CN111057824B CN201911295650.2A CN201911295650A CN111057824B CN 111057824 B CN111057824 B CN 111057824B CN 201911295650 A CN201911295650 A CN 201911295650A CN 111057824 B CN111057824 B CN 111057824B
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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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
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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
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Forging (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention relates to a method for improving medium carbon CrNi3Heat treatment process for Mo material forging grain size, and medium carbon CrNi with chemical composition meeting requirements3Normalizing the Mo forge piece for the first time, heating to 930-950 ℃, preserving heat for 1-2 hours, air cooling to 600-610 ℃, and preserving heat for 30-31 hours; normalizing for the second time, heating to 830-840 ℃, preserving heat for 1-2 hours, air cooling to 600-610 ℃, and preserving heat for 30-32 hours; performing sub-temperature quenching, heating to 770-780 ℃, preserving heat for 2-4 hours, and discharging for quenching; and (4) tempering, heating to 560-580 ℃, preserving heat for 2-4 hours, discharging from the furnace, and cooling to room temperature by water. The method adopts twice normalizing heat treatment to separate bainite tissue inheritance and adjust the tissue; the structure is homogenized by sub-temperature quenching, and the crystal grains are further refined; tempering to obtain medium carbon CrNi with corresponding mechanical property3The grain size of the Mo material forged piece can reach 11-12 grades.
Description
Technical Field
The invention relates to a process method for manufacturing a steel forging, in particular to a process method capable of improving medium carbon CrNi3A heat treatment process of Mo material forging grain size.
Background
Medium carbon CrNi3The Mo material forging is alloy structural steel, has good comprehensive mechanical properties after quenching and tempering, and is widely applied to various industries.
Medium carbon CrNi3The Mo material forging is subjected to the traditional heat treatment process: quenching and high-temperature tempering, and the grain size can generally reach about 8 grades. When the grain size is required to be higher, the requirement can not be met only by the traditional heat treatment process of quenching and high-temperature tempering. Therefore, it is necessary to provide a medium carbon CrNi3Heat treatment process for Mo material forging with higher grain size
CN103320591B discloses a heat treatment method for a 30CrNiMoV forging, which sequentially comprises the following steps: primary normalizing, primary supercooling, secondary normalizing, secondary supercooling, complete annealing and quenching and tempering; wherein the first normalizing comprises the following steps: heating the forging to 970-990 ℃, and keeping the temperature for 13-18 h; the second normalizing comprises the following steps: heating the forge piece to 940-960 ℃, and keeping the temperature for 13-18 h; the complete annealing is as follows: heating the forge piece to 850 ℃ for 15h, cooling in a furnace for 640-660 ℃, keeping the temperature for 28-32 h, and then air-cooling until the temperature of the forge piece is not higher than 150 ℃; the thermal refining comprises the following steps in sequence: heating the forging to 860-880 ℃, keeping the temperature for 8-12 h, then quenching, heating the forging to 580-600 ℃, keeping the temperature for 18-22 h, and then tempering; the first supercooling and the second supercooling are both: and after the forging is cooled to 200 ℃, cooling the forging to room temperature in air. The method is characterized in that the once normalizing temperature after forging is increased to reorder the uneven grain structure after forging, then the normalizing with slightly lower temperature is carried out again to further refine the grains, the two times of low-temperature supercooling can fully decompose the residual austenite generated by the normalizing and block the genetic tendency, and finally the complete annealing is carried out to completely block the tissue inheritance, thereby achieving the ideal effect of eliminating mixed crystals
Disclosure of Invention
The invention aims to provide a method for separating bainite structure inheritance and adjusting the structure to obtain pearlite + ferrite aiming at the current situation; homogenizing the structure and refining grains; can improve medium carbon CrNi with corresponding mechanical properties3A heat treatment process of Mo material forging grain size.
The invention aims to realize the mode that the medium carbon CrNi can be improved3Heat treatment process of Mo material forging grain size, the medium carbonCrNi3The Mo material forging has the following chemical components by smelting analysis: c: 0.37-0.38%, Cr: 1.32 to 1.44%, Ni: 3.2-3.48%, Mo: 0.33-0.35%, V: 0.13-0.16%;
the heat treatment process of the medium carbon CrNi3Mo material forge piece adopts a heat treatment mode of normalizing, sub-temperature quenching and tempering, and comprises the following specific steps:
1) normalizing for the first time: firstly, heating to 930-950 ℃, preserving heat for 1-2 hours, and then discharging from the furnace and air cooling; air cooling to 600-610 ℃, and then preserving heat for 30-31 hours;
2) normalizing for the second time: reheating to 830-840 ℃, preserving heat for 1-2 hours, and then discharging and air cooling; air cooling to 600-610 ℃, then preserving the heat for 30-32 hours, and then air cooling to room temperature;
3) and (3) sub-temperature quenching: heating to 770-780 ℃, preserving heat for 2-4 hours, and then taking out of the furnace for quenching, wherein the quenching medium is water, and the cooling time is 3-6 minutes;
4) tempering: heating to 560-580 ℃, preserving heat for 2-4 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
The method comprises the steps of firstly adopting twice normalizing heat treatments to separate bainite tissue inheritance and adjust the tissue to obtain pearlite and ferrite; then, performing sub-temperature quenching, homogenizing the structure, and further refining the crystal grains; finally, corresponding mechanical properties are obtained through tempering.
The invention can lead the medium carbon CrNi to be3The grain size of the Mo material forging reaches 11-12 grades.
Detailed Description
The invention adopts a heat treatment mode of normalizing, sub-temperature quenching and tempering. Medium carbon CrNi3The complete recrystallization temperature of the Mo material is about 920-950 ℃, the first normalizing is 930-950 ℃, and the Mo material enters a furnace to be insulated at the static complete recrystallization temperature through normalizing and cooling to 600 ℃, so that the tissue inheritance can be isolated; the second normalizing temperature is reduced to 840-850 ℃, the crystal grains can be refined, and the second normalizing is carried out based on the poor control of the first normalizing crystal grains. And (4) carrying out two normalizing heat treatments to separate bainite tissue inheritance and adjust the tissue to obtain pearlite and ferrite.
The invention adds one-time sub-temperature quenching with the heating temperature of 770-780 ℃ between normal complete quenching and tempering, homogenizes the structure, further refines the crystal grains, obtains a proper amount of fine ferrite structure which is uniformly distributed, and increases the content of carbon and alloy elements in austenite due to the presence of a small amount of unmelted ferrite in the structure, and can also prevent the initiation and the expansion of cracks due to the presence of a small amount of stable residual austenite after quenching.
The sub-temperature quenching temperature is low, undissolved ferrite refined by deformation quenching can prevent grains from growing large, superfine austenite grains can be formed along the original coarse austenite grain boundary before quenching, the grains are refined, the grain boundary is increased, so the content of harmful impurity elements on the unit interface is reduced, the toughness is increased, and the notch sensitivity is reduced.
And finally, tempering to stabilize the structure and eliminate internal stress. The tempering temperature is determined by the mechanical properties required for the material forging.
The medium carbon CrNi subjected to the heat treatment of the invention3The grain size of the Mo material forging can reach 11-12 levels.
The invention is described in more detail below with reference to specific examples:
example 1 Medium carbon CrNi3The Mo material forging has the following chemical component smelting analysis: c: 0.38%, Cr: 1.44%, Ni: 3.48%, Mo: 0.33%, V: 0.13 percent.
1) Normalizing for the first time: firstly, heating to 940 ℃, preserving heat for 1 hour, and then discharging from the furnace and air cooling; after air cooling to 610 ℃, the temperature is kept for 31 hours.
2) Normalizing for the second time: reheating to 830 ℃, preserving heat for 1 hour, and then discharging and air cooling; after air cooling to 610 ℃, preserving the heat for 30 hours; and then air-cooling to room temperature.
3) And (3) sub-temperature quenching: heating to 780 ℃, preserving heat for 2 hours, then taking out of the furnace for quenching, wherein the quenching medium is water, and the cooling time is 3 minutes.
4) Tempering: heating to 570 ℃, preserving heat for 2 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
After heat treatment, medium carbon CrNi3The actual grain size of the Mo material forging is 12 grades.
Example 2 Medium carbon CrNi3Mo materialThe chemical composition melting analysis of the forgings is as follows: c: 0.37%, Cr: 1.32%, Ni: 3.33%, Mo: 0.33%, V: 0.15 percent.
1) Normalizing for the first time: firstly heating to 950 ℃, preserving heat for 1.5 hours, and then discharging from the furnace and air cooling; after air cooling to 600 ℃, heat preservation is carried out for 30 hours.
2) Normalizing for the second time: re-heating to 840 ℃, preserving heat for 1.5 hours, and then discharging and air cooling; after air cooling to 600 ℃, preserving the heat for 32 hours; and then air-cooling to room temperature.
3) And (3) sub-temperature quenching: heating to 770 ℃, preserving heat for 3 hours, then taking out of the furnace for quenching, wherein the quenching medium is water, and cooling for 5 minutes.
4) Tempering: heating to 580 deg.C, holding for 3 hr, taking out, cooling with water, and cooling to room temperature.
After this heat treatment, medium carbon CrNi3The actual grain size of the Mo material forging is 11 grades.
Example 3 Medium carbon CrNi3The Mo material forging has the following chemical component smelting analysis: c: 0.37%, Cr: 1.36%, Ni: 3.2%, Mo: 0.35%, V: 0.16 percent.
1) Normalizing for the first time: firstly heating to 930 ℃, preserving heat for 2 hours, and then discharging from the furnace and air cooling; after air cooling to 600 ℃, the temperature is kept for 31 hours.
2) Normalizing for the second time: re-heating to 840 ℃, preserving heat for 2 hours, and then discharging from the furnace and air cooling; after air cooling to 600 ℃, preserving the heat for 30 hours; and then air-cooling to room temperature.
3) And (3) sub-temperature quenching: heating to 780 ℃, preserving heat for 4 hours, then taking out of the furnace for quenching, wherein the quenching medium is water, and cooling for 6 minutes.
4) Tempering: heating to 560 ℃, preserving heat for 4 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
After this heat treatment, medium carbon CrNi3The actual grain size of the Mo material forging is 11.5 grade.
To confirm the necessity of adopting the heat treatment mode of normalizing, sub-temperature quenching and tempering, the applicant performed comparative experiments of different processes on example 1, and the specific experiments are as follows:
comparative example 1, intermediate carbon CrN to be heat treated in example 1i3The Mo material forging adopts a conventional quenching and high-temperature tempering heat treatment process, which comprises the following steps:
1) quenching: firstly heating to 880 ℃, preserving heat for 1 hour, then discharging from the furnace and quenching, wherein the quenching medium is water, and the cooling time is 3 minutes.
2) High-temperature tempering: heating to 570 ℃, preserving heat for 2 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
After this heat treatment, medium carbon CrNi3The actual grain size of the Mo material forging is 8 grades.
Comparative example 2, the intermediate carbon CrNi to be heat-treated in example 13The Mo material forging adopts a heat treatment process of normalizing, quenching and high-temperature tempering:
1) normalizing: firstly heating to 890 ℃, preserving heat for 1 hour, and then taking out of the furnace and rapidly cooling by adopting an air blower.
2) Quenching: reheating to 880 ℃, preserving heat for 1 hour, then discharging from the furnace and quenching, wherein the quenching medium is water, and the cooling time is 3 minutes.
3) High-temperature tempering: heating to 570 ℃, preserving heat for 2 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
Compared with the comparative example 1, the comparative example 2 adds a normalizing procedure, the grain size is improved to a certain extent, and the medium carbon CrNi3The actual grain size of the Mo material forging is 9 grades.
Comparative examples 1 and 2 of carbon CrNi3The actual grain size of the Mo material forging is 8 grades and 9 grades, which is relative to the medium carbon CrNi in the embodiment 13The actual grain size of the Mo material forging is 12 grades, and the difference is very large.
The method comprises the steps of firstly adopting twice normalizing heat treatments to separate bainite tissue inheritance and adjust the tissue to obtain pearlite and ferrite; then, performing sub-temperature quenching, homogenizing the structure, and further refining the crystal grains; finally, corresponding mechanical properties are obtained through tempering.
Claims (1)
1. Increase medium carbon CrNi3The heat treatment process of the grain size of the Mo material forging is characterized by comprising the following steps: medium carbon CrNi3The Mo material forging has the following chemical components by smelting analysis: c: 0.37-0.38%, Cr: 1.32 to 1.44%, Ni:3.2-3.48%, Mo: 0.33-0.35%, V: 0.13-0.16%; the balance of iron and inevitable impurities;
the heat treatment process of the medium carbon CrNi3Mo material forge piece adopts a heat treatment mode of normalizing, sub-temperature quenching and tempering, and comprises the following specific steps:
1) normalizing for the first time: firstly, heating to 930-950 ℃, preserving heat for 1-2 hours, and then discharging from the furnace and air cooling; air cooling to 600-610 ℃, and then preserving heat for 30-31 hours;
2) normalizing for the second time: reheating to 830-840 ℃, preserving heat for 1-2 hours, and then discharging and air cooling; air cooling to 600-610 ℃, then preserving the heat for 30-32 hours, and then air cooling to room temperature;
3) and (3) sub-temperature quenching: heating to 770-780 ℃, preserving heat for 2-4 hours, and then taking out of the furnace for quenching, wherein the quenching medium is water, and the cooling time is 3-6 minutes;
4) tempering: heating to 560-580 ℃, preserving heat for 2-4 hours, then discharging from the furnace, cooling by water, and cooling to room temperature.
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| CN112322867B (en) * | 2020-10-26 | 2023-03-21 | 武汉重工铸锻有限责任公司 | Heat treatment process for improving comprehensive mechanical properties of Cr-Ni-Mo large-scale forging for nuclear power |
| CN113862434B (en) * | 2021-09-18 | 2023-03-31 | 河南中原特钢装备制造有限公司 | Heat treatment process of 35CrNi3MoVR material for thick-wall ultrahigh-pressure container |
| CN113957354B (en) * | 2021-10-29 | 2022-10-25 | 河南中原特钢装备制造有限公司 | Avoidance of PCrNi 3 Method for stable overheating of MoV forge piece due to genetic formation of crystal grains |
Citations (5)
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| SU779412A1 (en) * | 1978-06-22 | 1980-11-15 | Ордена Трудового Красного Знамени Научно-Исследовательский Институт Технологии Автомобильной Промышленности | Method of isothermal annealing of alloy steel billets |
| JPS60162722A (en) * | 1984-02-02 | 1985-08-24 | Daihatsu Motor Co Ltd | Heat treatment of hot forged parts |
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| CN105838856A (en) * | 2016-05-14 | 2016-08-10 | 莱芜锻压有限公司 | Step type normalizing technology for 25Cr2Ni4MoV forged piece |
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2019
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| JPS60162722A (en) * | 1984-02-02 | 1985-08-24 | Daihatsu Motor Co Ltd | Heat treatment of hot forged parts |
| 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 |
| CN103343200A (en) * | 2013-07-01 | 2013-10-09 | 江阴市恒业锻造有限公司 | Short-process thermal treatment method of large 35CrNi3MoV steel forgings |
| CN105838856A (en) * | 2016-05-14 | 2016-08-10 | 莱芜锻压有限公司 | Step type normalizing technology for 25Cr2Ni4MoV forged piece |
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