CN102230065A - Heat treatment process for improving low-temperature impact toughness of pipeline steel - Google Patents
Heat treatment process for improving low-temperature impact toughness of pipeline steel Download PDFInfo
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- CN102230065A CN102230065A CN 201110150172 CN201110150172A CN102230065A CN 102230065 A CN102230065 A CN 102230065A CN 201110150172 CN201110150172 CN 201110150172 CN 201110150172 A CN201110150172 A CN 201110150172A CN 102230065 A CN102230065 A CN 102230065A
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Abstract
The invention discloses a heat treatment process for improving low-temperature impact toughness of pipeline steel, comprising the following steps of: first, quenching a pipeline steel plate after heating the pipeline steel plate to reach 940 DEG C and preserving the heat of the pipeline steel plate for 1 hour; next, heating the quenched steel plate to reach a temperature which is 20-40 DEG C less than the Ac3 temperature, and quenching the steel plate after preserving the heat for 1 hour; and finally, discharging the steel plate out of the furnace and cooling the steel plate by air so as obtain pipeline steel with excellent low temperature impact toughness after heating the steel plate which is quenched twice to reach a temperature of 400-450 DEG C and preserving the heat for 40-80 min. According to the invention, the low temperature impact toughness can be largely improved, the mechanical property of the pipeline steel can be optimized and requirements on the property of the traditional petroleum and natural gas pipeline engineering can be completely satisfied while the strength of the pipeline steel is reduced to a smaller degree. The heat treatment process for improving the low-temperature impact toughness of the pipeline steel, disclosed by the invention, is especially suitable for high-toughness X120 pipeline steel plates.
Description
Technical field
The present invention relates to a kind of thermal treatment process of high-grade pipe line steel, particularly a kind of thermal treatment process of high strength X120 pipe line steel, specifically a kind of thermal treatment process that improves the pipe line steel low-temperature impact toughness.
Background technology
Oil, Sweet natural gas are the important energy source that human society is depended on for existence, are rely one of basic substances of development of economic society.At present, explored oil gas mainly concentrates on deep-sea and the abominable remote mountain areas of envrionment conditions, and the demand market of oil gas concentrates on the city.Gas pipeline has become oil gas and has carried the most economical and effective instrument as connecting these two geographic bridges.
Factors such as public safety that attracts people's attention and environmental problem and pipeline manufacturing and installation cost make pipeline design adopt higher intensity, good crack arrest characteristic, anti-hydrogen induced cracking ability, good welding and forming property etc.At present, the X80 pipe line steel obtains a large amount of application on the transfering natural gas from the west to the east multiple line engineering of China.The application of X120 pipe line steel has huge economic benefit, can make long distance oil-gas pipeline cost savings 5%～12% and 5%～18% respectively, be mainly reflected in material economy, improve transfer pressure, reduce construction volume, reduce maintenance cost, optimize aspect such as overall plan.
In machine building, extensively adopt structure iron such as low, middle carbon carbon steel or low, medium carbon low alloy steel.The traditional thermal treatment process of structure iron is modified, and promptly quenching fully increases temperature tempering.The quenching gained is organized as martensite, is tempered sorbite behind the high tempering.This kind microstructure provides intensity and flexible good combination.It is to avoid not molten ferrite occurring and the performance depreciation that makes steel that the hypoeutectoid structure iron is adopted the reason of quenching fully.Along with the development of reinforcement toughening process, people find in production practice and scientific experimentation, adopt slack quenching to help to improve its toughness when not reducing the strength of materials to hypoeutectoid steel but in recent years.So-called intercritical hardening, that is the slack quenching of hypoeutectoid steel, or claim critical area quenching, two-phase region heating quenching are steel to be heated to austenite and the ferrite two-phase region quenches.Intercritical hardening and tempering subsequently are a kind of tough coupling of steel technology preferably that makes.This technology is woven with and must asks the original set of steel, generally all need once quench fully or modifier treatment before intercritical hardening.
Have non-equilibrium original structure steel such as martensite, bainite, the intensity behind intercritical hardening, plasticity and toughness all are better than the steel that original structure is the normalizing attitude.The performance of martensite, upper bainite and lower bainite is approaching substantially, and promptly non-equilibrium microstructure all can obtain good obdurability as the original structure of intercritical hardening.The highly malleablized effect of intercritical hardening is relevant with biphase relative quantity and form, wherein intensity depends primarily on martensitic relative quantity, form and " reinforcement " ferritic reinforcing degree, and toughness and plasticity depend primarily on ferritic form and distribution.Intercritical hardening can obviously suppress the temper brittleness of steel.
Summary of the invention
The purpose of this invention is to provide a kind of thermal treatment process that improves the pipe line steel low-temperature impact toughness, this technology significantly improves its low-temperature impact toughness when less degree reduces pipe line steel intensity, make pipe line steel have high strength and good low-temperature impact toughness simultaneously.
The objective of the invention is to realize by following technical scheme:
A kind of thermal treatment process that improves the pipe line steel low-temperature impact toughness is characterized in that this thermal treatment process comprises following operation:
1) the pipe line steel steel plate is heated to 930～950 ℃, quenches behind the insulation 0.5-1.5h;
2) steel plate after will quenching is heated to A once more
C3Following 20 ~ 40 ℃ of temperature is quenched behind the insulation 0.5-1.5h;
3) steel plate after twice quenching is heated to 400 ~ 450 ℃, the air cooling of coming out of the stove behind insulation 40 ~ 80min obtains excellent low temperature impact flexible pipe line steel.
In the step 1) of the present invention, the pipe line steel steel plate can be heated to 940 ℃, quench behind the insulation 1h.
Described pipe line steel is high tough X120 pipe line steel steel plate, and its chemical ingredients mass ratio is: C 0.03 ~ 0.06, and Si 0.2 ~ 0.4, Mn 1 ~ 1.8, P＜0.005, S＜0.001, N＜0.006, Nb 0.03 ~ 0.08, and B 0.001 ~ 0.0015, and Ni 0.3 ~ 0.6, Cr 0.1 ~ 0.4, Cu 0.1 ~ 0.4, and Mo 0.1 ~ 0.5, and surplus is Fe and trace impurity.
The present invention is specially adapted in the high tough X120 pipe line steel steel plate, and described height is tough, and X120 pipe line steel steel plate is obtained by cooling controlling and rolling controlling process.The thickness of slab of described height is tough X120 pipe line steel steel plate is 12.7mm.
The present invention can effectively solve the low contradiction of X120 pipe line steel intensity high impact toughness, when less degree reduces the intensity of X120 pipe line steel, can significantly improve its low-temperature impact toughness (30 ℃), optimized the mechanical property of X120 pipe line steel, made it satisfy the performance requirement of present oil and gas pipeline engineering fully.
Effect of the present invention is as follows:
1) the present invention's crystal grain thinning significantly.After quenching in advance, the non-equilibrium microstructure bainite that obtains has high dislocation density, and when two-phase region heated, the partial dislocation in the non-equilibrium microstructure had kept, and these energy of dislocation increase austenitic nucleation rate, and austenitic initial crystal grain is by refinement; Owing to have the not molten ferrite of plasticity in the tissue, hinder the austenite grain boundary migration, suppress it and grow up; Because the two-phase region quenching temperature is lower, be unfavorable for atomic diffusion simultaneously, crystal boundary migration speed is less.Finally cause austenite crystal obviously by refinement.
2) thermal treatment process of the present invention is to quench at two-phase region, so can have the not molten ferrite of a part in the tissue behind the heat tracing, after the quenching, this part not molten ferrite has kept, and distributes alternately with the non-equilibrium phase bainite.Because ferrite belongs to the plasticity phase, so can improve the low-temperature impact toughness (30 ℃) of steel.
3) after twice quenching of the present invention, after 400 ~ 450 ℃ of tempering, when reducing the intensity of X120 pipe line steel, less degree can significantly improve its low-temperature impact toughness.
Description of drawings
Fig. 1 is the organization chart that the embodiment of the invention 1 obtains.
Fig. 2 is the organization chart that the embodiment of the invention 2 obtains.
Fig. 3 is the organization chart that the embodiment of the invention 3 obtains.
Embodiment
Be specific embodiments of the invention below:
Below be the thermal treatment process of three kinds of X120 pipe line steels of the present invention, adopt the X120 pipe line steel steel plate of 12.7mm.Steel plate is put into chamber type electric resistance furnace be heated to 940 ℃ of insulation 1h quenching, and then be heated to 820 ~ 860 ℃ respectively, insulation 1h quenches, and is heated to 400 ~ 450 ℃ more respectively at last, insulation 40 ~ 80min, the air cooling of coming out of the stove.Concrete technology sees Table 1, and Fig. 1 is the organization chart that the embodiment of the invention 1 obtains.Fig. 2 is the organization chart that the embodiment of the invention 2 obtains.Fig. 3 is the organization chart that the embodiment of the invention 3 obtains.
X120 pipe line steel steel plate after the thermal treatment is carried out Mechanics Performance Testing, and compare with the mechanical property of original steel plate (rolling attitude), every performance of the steel plate after the thermal treatment satisfies index request fully as can be seen, and concrete parameter sees Table 2(and annotates: above-mentioned detection is the horizontal performance of steel plate).
The heat treatment step of table 1 embodiment
The mechanical property parameters of table 2 embodiment
Claims (5)
1. thermal treatment process that improves the pipe line steel low-temperature impact toughness is characterized in that this thermal treatment process comprises following operation:
The pipe line steel steel plate is heated to 930～950 ℃, quenches behind the insulation 0.5-1.5h;
Steel plate after quenching is heated to A once more
C3Following 20 ~ 40 ℃ of temperature is quenched behind the insulation 0.5-1.5h;
Steel plate after twice quenching is heated to 400 ~ 450 ℃, and the air cooling of coming out of the stove behind insulation 40 ~ 80min obtains excellent low temperature impact flexible pipe line steel.
2. the thermal treatment process of raising pipe line steel low-temperature impact toughness according to claim 1 is characterized in that: in the step 1), the pipe line steel steel plate is heated to 940 ℃, quenches behind the insulation 1h.
3. the thermal treatment process of raising pipe line steel low-temperature impact toughness according to claim 1 is characterized in that: described pipe line steel is high tough X120 pipe line steel steel plate, and its chemical ingredients mass ratio is: C 0.03 ~ 0.06, Si 0.2 ~ 0.4, and Mn 1 ~ 1.8, P＜0.005, S＜0.001, N＜0.006, Nb 0.03 ~ 0.08, B 0.001 ~ 0.0015, Ni 0.3 ~ 0.6, and Cr 0.1 ~ 0.4, and Cu 0.1 ~ 0.4, Mo 0.1 ~ 0.5, and surplus is Fe and trace impurity.
4. the thermal treatment process of raising pipe line steel low-temperature impact toughness according to claim 3 is characterized in that: described height is tough, and X120 pipe line steel steel plate is obtained by cooling controlling and rolling controlling process.
5. the thermal treatment process of raising pipe line steel low-temperature impact toughness according to claim 3 is characterized in that: the thickness of slab of described height is tough X120 pipe line steel steel plate is 12.7mm.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105463286A (en) * | 2015-12-10 | 2016-04-06 | 无锡拓能自动化科技有限公司 | Pipeline suitable for conveying natural gas and manufacturing method of pipeline |
| CN105506250A (en) * | 2015-12-10 | 2016-04-20 | 南京钢铁股份有限公司 | Heat treatment process capable of improving NDT performance of steel for F-grade ultrahigh-strength ocean platform |
| CN110106445A (en) * | 2019-06-05 | 2019-08-09 | 上海大学 | One kind is for ocean platform cast node high intensity high/low temperature toughness steel and preparation method thereof |
| CN110983001A (en) * | 2019-12-27 | 2020-04-10 | 江苏南钢通恒特材科技有限公司 | 32CrB4 induction hardening and tempering process |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1152031A (en) * | 1996-10-11 | 1997-06-18 | 杨希敏 | Prodn process of biphase cast steel hook |
| US20090242084A1 (en) * | 2006-09-13 | 2009-10-01 | Ralf Bode | Method for Producing a Shaft for Compressors |
-
2011
- 2011-06-07 CN CN 201110150172 patent/CN102230065A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1152031A (en) * | 1996-10-11 | 1997-06-18 | 杨希敏 | Prodn process of biphase cast steel hook |
| US20090242084A1 (en) * | 2006-09-13 | 2009-10-01 | Ralf Bode | Method for Producing a Shaft for Compressors |
Non-Patent Citations (1)
| Title |
|---|
| 《中国冶金》 20101231 张凯等 组织状态对X120管线钢力学性能的影响 9-14 1-5 第20卷, 第12期 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105463286A (en) * | 2015-12-10 | 2016-04-06 | 无锡拓能自动化科技有限公司 | Pipeline suitable for conveying natural gas and manufacturing method of pipeline |
| CN105506250A (en) * | 2015-12-10 | 2016-04-20 | 南京钢铁股份有限公司 | Heat treatment process capable of improving NDT performance of steel for F-grade ultrahigh-strength ocean platform |
| CN105506250B (en) * | 2015-12-10 | 2018-02-02 | 南京钢铁股份有限公司 | A kind of Technology for Heating Processing of the strong offshore platform steel NDT performances of raising F level superelevation |
| CN110106445A (en) * | 2019-06-05 | 2019-08-09 | 上海大学 | One kind is for ocean platform cast node high intensity high/low temperature toughness steel and preparation method thereof |
| CN110106445B (en) * | 2019-06-05 | 2021-04-16 | 上海大学 | High-strength high-low-temperature-toughness steel for ocean platform casting node and preparation method thereof |
| CN110983001A (en) * | 2019-12-27 | 2020-04-10 | 江苏南钢通恒特材科技有限公司 | 32CrB4 induction hardening and tempering process |
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Application publication date: 20111102 |