CN112961964A - Differential temperature quenching technology for thick section steel for container - Google Patents
Differential temperature quenching technology for thick section steel for container Download PDFInfo
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- CN112961964A CN112961964A CN202110144117.7A CN202110144117A CN112961964A CN 112961964 A CN112961964 A CN 112961964A CN 202110144117 A CN202110144117 A CN 202110144117A CN 112961964 A CN112961964 A CN 112961964A
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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
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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
- C21D2211/002—Bainite
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Abstract
The invention discloses a differential temperature quenching technology for thick section steel for a container, belonging to the technical field of steel part quenching, and the technical scheme is characterized by comprising the following steps: s1, roughly machining a forge piece; s2, quenching and heat preservation of the forged piece: quenching and heating the forge piece to T1, and then preserving heat; s3, differential heating of the forge piece: heating the forge piece to the temperature T2, and then preserving heat; s4, quenching and cooling the forged piece: transferring the forged piece into a quenching water tank; s5, tempering the forged piece; s6, forge piece detection, the method has the advantages that the temperature loss of the near surface of the container when the thick-section forge piece is quenched is reduced, the nonuniformity of the whole-section structure performance of the forge piece is reduced, and the heat treatment quality of the product is improved.
Description
Technical Field
The invention relates to the technical field of steel part quenching, in particular to a differential temperature quenching technology for thick section steel for a container.
Background
With the rapid development of economy in China, the national requirement for energy self-sufficiency is increased day by day, and the energy safety of the country is powerfully guaranteed by the autonomous manufacturing of heavy container equipment in nuclear power and petrochemical industries. The nuclear power and petrochemical container develops towards the direction of large size, large wall thickness, high strength and high toughness, and simultaneously, higher requirements are provided for the structural property uniformity of the whole wall thickness of the forging.
The quenching differential heating technology of the thick section steel for the container can solve the near-surface temperature loss phenomenon in the quenching transfer process of the large-size and large-wall-thickness container forge piece. The temperature loss of the near surface of the forging can cause the near surface to precipitate proeutectoid ferrite in advance, the internal and external structure performance of the forging is not uniform, and the performance of the forging is unqualified in severe cases.
Disclosure of Invention
The invention aims to provide a differential temperature quenching technology for thick-section steel for a container, which has the advantages of reducing the temperature loss of the near surface of a thick-section forging for quenching the container, reducing the nonuniformity of the overall section structure performance of the forging and improving the heat treatment quality of a product.
The technical purpose of the invention is realized by the following technical scheme:
a differential temperature quenching technology for thick section steel for a container comprises the following steps: s1, roughly machining a forge piece; s2, quenching and heat preservation of the forged piece: quenching and heating the forge piece to T1, and then preserving heat; s3, differential heating of the forge piece: heating the forge piece to the temperature T2, and then preserving heat; s4, quenching and cooling the forged piece: transferring the forged piece into a quenching water tank; s5, tempering the forged piece; and S6, detecting the forged piece.
Further, in step S2, the holding temperature T1 is set to a range of 30 to 50 ℃ inclusive of Ac3 of the hypoeutectoid steel.
Further, in step S2, the heat preservation time is determined according to the thickness of the forged piece, and the heat preservation time is at least 1 hour every 50 mm.
Further, in step S3, the holding temperature T2 ═ T1+ (0-50) ° c, and T2 should be lower than the austenite grain coarsening temperature of the present steel.
Further, in step S3, the temperature is raised at a rate of 100 ℃/H, and the temperature is maintained for 0.5-1H after the temperature is uniform.
Further, in step S4, the rotation time is controlled within 15 min.
Further, in step S5, the forging is reheated to a critical temperature a1 or less, and then heat-preserved, and finally air-cooled to room temperature.
In conclusion, the invention has the following beneficial effects:
1. the temperature loss of the near surface of the container during the quenching of the thick-section forge piece is reduced, the nonuniformity of the whole-section structure performance of the forge piece is reduced, and the heat treatment quality of the product is improved;
2. the near-surface cooling of the forging in the isothermal quenching transfer process precipitates proeutectoid ferrite in advance, so that the product performance is reduced; by applying the differential temperature quenching technology, the internal and external temperature uniformity is high during the quenching of the forgings, and the full-wall thickness structure performance is uniform.
Drawings
FIG. 1 is a schematic representation of the steps of a differential quenching technique for thick section steel for containers;
FIG. 2 is a graph of room temperature tensile strength and 0 ℃ average work of impact data for a forging;
FIG. 3 is a metallographic structure of the inner surface of a forging of example 1;
FIG. 4 is a metallographic structure representation of the forging of example 1 at inner wall 1/4;
FIG. 5 is a metallographic structure of the inner surface in example 2;
FIG. 6 is a metallographic structure diagram of the inner surface in example 3.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Example 1: a differential quenching technique for thick section steel for containers, as shown in fig. 1, comprising the steps of:
s1, rough machining of forgings: the steel grade adopted by the forged piece is 20MnMoNb, the forged piece has the outer diameter phi of 5000 mm, the wall thickness of 350 mm, the height of 2400 mm and the weight of about 96 tons.
S2, quenching and heat preservation of the forged piece: the forging is quenched and heated to T1, the heat preservation temperature T1 is set in the range of 30-50 ℃ above Ac3 of the hypoeutectoid steel, the optimal quenching temperature T1 of 20MnMoNb is 900 ℃, the heat preservation time is determined according to the thickness of the forging, the heat preservation time is at least 1 hour per 50mm, and therefore the heat preservation time of the forging is more than or equal to 7H.
S3, differential heating of the forge piece: the temperature of the forge piece is raised to T2, T2 is T1+ (0-50) DEG C, and T2 is lower than the austenite grain coarsening temperature of the steel, in the embodiment, T2 is set to 900 ℃, the temperature raising speed is 100 ℃/H, the furnace temperature is uniform, and then the temperature is kept for 0.5H.
S4, quenching and cooling the forged piece: and (4) transporting the forged piece to a quenching water tank by using a traveling crane, and controlling the timing transportation time within 12 minutes.
S5, tempering: after quenching is finished, the forge piece is reheated to be below the critical temperature A1, the actual heat preservation temperature is 640 ℃, the forge piece heat preservation time is more than or equal to 7h, and then air cooling is carried out.
S6, detecting the forged piece: after the forging is tempered, mechanical property inspection is carried out on the outer surface, the outer 1/4 wall thickness, the 1/2 wall thickness, the inner 1/4 wall thickness and the inner surface of the forging at 5 sampling depths, the fluctuation range of the mechanical property of the whole section is reasonable, the room-temperature tensile strength (Rm) is more than or equal to 610MPa, the 0 ℃ average impact energy (AvgKvValue) is more than or equal to 80J, and the product quality is stable and reliable. And (5) inspecting that the metallographic structure form of each sampling depth is a bainite tempered structure.
Example 2: a differential quenching technique for thick section steel for a container, which is different from the technique of example 1, comprises the following steps:
s2, quenching and heat preservation of the forged piece: the forging is quenched and heated to T1, the heat preservation temperature T1 is set in the range of 30-50 ℃ above Ac3 of the hypoeutectoid steel, T1 is 900 ℃ in the embodiment, and the heat preservation time of the forging is more than or equal to 7H.
S3, differential heating of the forge piece: the temperature of the forge piece is raised to T2, T2 is T1+ (0-50) DEG C, and T2 is lower than the austenite grain coarsening temperature of the steel, in the embodiment, T2 is set to 930 ℃, the temperature raising speed is 100 ℃/H, the furnace temperature is uniform, and then the temperature is kept for 0.5H.
Example 3: a differential quenching technique for thick section steel for a container, which is different from the technique of example 1, comprises the following steps:
s2, quenching and heat preservation of the forged piece: the forging is quenched and heated to T1, the heat preservation temperature T1 is set in the range of 30-50 ℃ above Ac3 of the hypoeutectoid steel, T1 is 900 ℃ in the embodiment, and the heat preservation time of the forging is more than or equal to 7H.
S3, differential heating of the forge piece: the temperature of the forge piece is raised to T2, T2 is T1+ (0-50) DEG C, and T2 is lower than the austenite grain coarsening temperature of the steel, in the embodiment, T2 is set to 950 ℃, the temperature raising speed is 100 ℃/H, the furnace temperature is uniform, and then the temperature is kept for 0.5H.
The experimental detection proves that:
1. tempering mechanical property detection data: 3 groups, each requiring a total of 5 samples of outer surface, outer 1/4 wall thickness, 1/2 wall thickness, inner 1/4 wall thickness, inner surface.
2. The results of the experiment are shown in FIG. 2.
And (4) analyzing results: the tensile strength and the 0 ℃ impact power of the inner and outer surfaces of the forged piece are low; in the embodiment 2, the tensile strength and the impact power at 0 ℃ at each sampling position are relatively uniform; in example 3, the tensile strength of the inner and outer surfaces was improved, but the 0 ℃ impact energy was reduced. The room temperature tensile strength in 3 examples meets the requirement of minimum 610MPa, and the average impact energy at 0 ℃ meets the requirement of minimum 82J.
And (3) metallographic detection after tempering:
the experimental results are as follows: the metallographic structure of the forging of the embodiment 1 is shown in a figure 1 and a figure 2, the metallographic structure of the forging of the embodiment 2 is shown in a figure 3, and the metallographic structure of the forging of the embodiment 3 is shown in a figure 4.
And (4) analyzing results: the metallographic structures of examples 1, 2 and 3 were compared, and the bainite tempered structure was mainly used for all of them. The inner surface of the steel plate in the embodiment 1 has a small amount of ferrite, the inner T/4 of the steel plate in the embodiment 1 is consistent with the inner surface structure of the steel plate in the embodiment 2, the structure of the steel plate in the embodiment 3 is thicker, the structure performance of the whole section is kept at the same level, and the product quality is stable and reliable.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (7)
1. The differential temperature quenching technology for the thick-section steel for the container is characterized by comprising the following steps of: s1, roughly machining a forge piece; s2, quenching and heat preservation of the forged piece: quenching and heating the forge piece to T1, and then preserving heat; s3, differential heating of the forge piece: heating the forge piece to the temperature T2, and then preserving heat; s4, quenching and cooling the forged piece: transferring the forged piece into a quenching water tank; s5, tempering the forged piece; and S6, detecting the forged piece.
2. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S2, the holding temperature T1 is set in the range of 30 to 50 ℃ inclusive over Ac3 of the hypoeutectoid steel.
3. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S2, the holding time is determined according to the thickness of the forging, and the holding time is at least 1 hour every 50 mm.
4. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S3, the holding temperature T2 is T1+ (0-50) DEG C, and T2 is lower than the austenite grain coarsening temperature of the steel.
5. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S3, the temperature is raised at a rate of 100 ℃/H, and the temperature is kept for 0.5-1H after the temperature is uniform.
6. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S4, the transit time is controlled to be within 15 min.
7. The differential quenching technique for thick section steel for containers as claimed in claim 1, wherein: in step S5, the forging is reheated to a critical temperature A1 or below, then heat preservation is carried out, and finally air cooling is carried out to the room temperature.
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| CN202110144117.7A CN112961964A (en) | 2021-02-02 | 2021-02-02 | Differential temperature quenching technology for thick section steel for container |
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| CN202110144117.7A CN112961964A (en) | 2021-02-02 | 2021-02-02 | Differential temperature quenching technology for thick section steel for container |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101906520A (en) * | 2009-06-02 | 2010-12-08 | 上海重型机器厂有限公司 | Heat-treatment technology method for lower end socket forge piece of nuclear power reactor pressure vessel |
| RU2431686C1 (en) * | 2010-05-11 | 2011-10-20 | Открытое акционерное общество "Ижорские заводы" | Procedure for complex thermal treatment of large-size forged blanks of chromium-molybdenum-vanadium steel |
| CN103305672A (en) * | 2013-06-27 | 2013-09-18 | 洛阳中创重型机械有限公司 | Heat treatment process for ultra-large type tube plate forge piece of pressure container |
| CN106222387A (en) * | 2016-07-25 | 2016-12-14 | 苏州热工研究院有限公司 | A kind of heat treatment method of nuclear island super-section forging |
| CN110904312A (en) * | 2019-12-09 | 2020-03-24 | 伊莱特能源装备股份有限公司 | Water-cooling quenching tempering process for large alloy steel forging |
-
2021
- 2021-02-02 CN CN202110144117.7A patent/CN112961964A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101906520A (en) * | 2009-06-02 | 2010-12-08 | 上海重型机器厂有限公司 | Heat-treatment technology method for lower end socket forge piece of nuclear power reactor pressure vessel |
| RU2431686C1 (en) * | 2010-05-11 | 2011-10-20 | Открытое акционерное общество "Ижорские заводы" | Procedure for complex thermal treatment of large-size forged blanks of chromium-molybdenum-vanadium steel |
| CN103305672A (en) * | 2013-06-27 | 2013-09-18 | 洛阳中创重型机械有限公司 | Heat treatment process for ultra-large type tube plate forge piece of pressure container |
| CN106222387A (en) * | 2016-07-25 | 2016-12-14 | 苏州热工研究院有限公司 | A kind of heat treatment method of nuclear island super-section forging |
| CN110904312A (en) * | 2019-12-09 | 2020-03-24 | 伊莱特能源装备股份有限公司 | Water-cooling quenching tempering process for large alloy steel forging |
Non-Patent Citations (1)
| Title |
|---|
| 李耀平: "基于数值模拟的20MnMoNb大厚锻件性能热处理工艺优化", 《锅炉技术》, vol. 49, no. 1, pages 53 - 57 * |
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