CN115058558A - Method for processing bainite hot formed steel - Google Patents
Method for processing bainite hot formed steel Download PDFInfo
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- CN115058558A CN115058558A CN202210555720.9A CN202210555720A CN115058558A CN 115058558 A CN115058558 A CN 115058558A CN 202210555720 A CN202210555720 A CN 202210555720A CN 115058558 A CN115058558 A CN 115058558A
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- Prior art keywords
- temperature
- heat preservation
- conveying
- mold
- steel
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 47
- 239000010959 steel Substances 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 32
- 229910001563 bainite Inorganic materials 0.000 title claims abstract description 22
- 238000012545 processing Methods 0.000 title claims abstract description 11
- 238000004321 preservation Methods 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 230000009466 transformation Effects 0.000 claims abstract description 13
- 239000000498 cooling water Substances 0.000 claims abstract description 8
- 238000005520 cutting process Methods 0.000 claims abstract description 6
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 4
- 239000012774 insulation material Substances 0.000 claims description 7
- 239000010425 asbestos Substances 0.000 claims description 4
- 229910052895 riebeckite Inorganic materials 0.000 claims description 4
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 claims description 3
- 239000011810 insulating material Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 229910000734 martensite Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
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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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
-
- 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
- C21D11/00—Process control or regulation for heat treatments
- C21D11/005—Process control or regulation for heat treatments for cooling
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
Abstract
The invention relates to a method for processing a bainite hot forming steel part, which comprises the steps of uncoiling and cutting a steel coil, conveying the steel coil to a heating furnace by using a conveying mechanism, and heating the steel coil to the temperature of 900-. And then conveying the heated plate to a stamping mechanism, stamping the plate to obtain a required part, controlling the cooling time of the part in a die with a cooling water channel to enable the temperature of the part to quickly pass through a pearlite transformation temperature interval, and taking out the part when the temperature of the part reaches a lower bainite transformation temperature. And finally, conveying the part to a heat preservation device, placing the part in a mold of the heat preservation device, and carrying out mold closing and heat preservation until the part is cooled to the bainite transformation finishing temperature. The method has low requirement on production equipment, is simple to operate, and can greatly increase the production efficiency. The tensile strength of the prepared part is kept above 1200mpa, the elongation is above 15%, and the product of strength and elongation of the material is greatly improved.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a method for processing a hot forming steel part, in particular to a method for processing a bainite hot forming steel part.
Background
The ultrahigh-strength hot forming steel has extremely high strength, the hot forming steel structure before forming is ferrite and pearlite, the tensile strength can reach 400-450 MPa, and the ultrahigh-strength hot forming steel has good formability; the tensile strength of the material after the steel plate is heated until the steel plate is fully austenitized and then cooled reaches more than 1500MPa, even can exceed 2000MPa, and the hardness of the material is comparable to that of ceramics and simultaneously has the toughness of steel. However, in the actual use process, the hot formed steel is in an all-martensite structure after heat treatment, so that the toughness is lower while the ultrahigh strength is ensured. Because the ultrahigh-strength hot-forming steel is commonly used for automobile bodies and other parts for protecting the personal safety of people, the poor toughness of the ultrahigh-strength hot-forming steel can cause the breakage of structures such as an A column, a B column, a threshold beam and the like in the collision process, and the life safety of passengers is damaged.
In order to solve this problem, techniques such as a thickened plate, low-strength hot-formed steel, etc. have been developed to improve the crash performance of the vehicle body. From a material standpoint alone, it is desirable to develop a high toughness hot formed steel that will resist material fracture, even if established with a small amount of sacrifice in material strength. At present, in order to obtain steel with better comprehensive mechanical properties, in the prior art, a heating coil of a hot stamping forming heating furnace is redesigned from improving a heating process, and finally, hot forming steel with performance zones is manufactured. Starting from the cooling process, the arrangement of water channels in the cooling die is changed, and the hot forming part with the soft area is also manufactured. However, the above patents all made the hot formed steel with performance zones, which makes the material deform at the variable parts to absorb energy. These techniques are highly demanding for production equipment and it is difficult to deal with the problem of different rebound deformations of parts when heated in different temperature zones. Therefore, how to provide a preparation method which has better mechanical property, low equipment requirement and simple operation by improving the integral structure of the material has important research value and practical significance.
Disclosure of Invention
In order to solve the problem of poor toughness of the mainstream martensite hot formed steel, the patent provides a method for processing bainite hot formed steel. The method utilizes the characteristic that bainite is a phase which is few in various steel structures and can not only consider the strength but also consider the toughness, and achieves the mode of a heat treatment path of high-temperature quick cooling and medium-temperature slow cooling by changing a heat treatment processing process and putting a part subjected to hot forming into a heat preservation die, so that the hot forming steel is finally processed into bainite hot forming steel with higher strength and better toughness.
The specific invention content is as follows:
a method of machining a bainite hot formed steel part comprising the steps of:
s1, unfolding the hot-formed steel coil by using an uncoiler, cutting the steel coil into plates, conveying the plates to a heating furnace by using a conveying mechanism, and heating to 900-1100 ℃ to make the plates fully austenitized;
s2, conveying the heated plate to a stamping mechanism, stamping the plate to obtain a required part, controlling the cooling time of the part in a die with a cooling water channel to enable the temperature of the part to rapidly pass through a pearlite transformation temperature range, and taking out the part when the temperature of the part reaches a lower bainite transformation temperature;
and S3, conveying the parts to a heat preservation device, placing the parts in a mold of the heat preservation device, and closing the heat preservation device and preserving heat until the parts are cooled to the bainite transformation finishing temperature.
Preferably, the cooling time of the part in the mold with the cooling water channel in the step S2 is 4-20S.
Preferably, the lower bainite transformation temperature in step S2 is 200 to 450 ℃.
Preferably, the mold closing and heat preservation time in the step S3 is 20-30 min, and the heat preservation temperature is 200-450 ℃.
Further, the heat preservation device in step S3 is composed of a mold and a heat preservation material.
Further, the mold is preheated at a temperature near the bainite transformation zone.
Furthermore, the heat insulation material group is arranged on the outer side of the die, and the cooling speed of the part can be controlled by replacing heat insulation materials with different thicknesses and thermal coefficients.
Preferably, the heat insulation material is asbestos or aluminum silicate.
The processing method of the bainite hot forming steel part focuses on the limitation of key technical parameters, and for other conventional steps, the processing steps can be carried out according to the mode disclosed by the prior art, so that the processing requirements can be met.
The invention has the beneficial effects that:
the method can solve the problem that the prior art is difficult to process different rebound deformations of parts heated in different temperature areas, and has low requirements on production equipment and simple operation.
The method does not need to modify a coil and a stamping die of a heating device or a thickened plate with high cost, only needs to control the cooling time of the part in the die with water cooling, and adds a pressure maintaining device. And the pressurizer adopts the soft mould, the soft mould does not need to adopt die steel, only needs ordinary steel materials, and low cost.
The cooling time of the part in the forming die is greatly reduced in the method, the part can be transferred to the soft die within 20s, and the production efficiency can be greatly improved.
The hot forming part produced by the method has the main structure of bainite, and the structure in steel can be controlled by adjusting the initial temperature of the part and the heat insulation material adopted by the heat insulation device, so that the part with corresponding performance is obtained.
The parts produced by the method can be flexibly applied to various scenes, and have important practical and economic values.
Drawings
FIG. 1 is a process flow diagram of a method of processing bainite hot formed steel.
FIG. 2 is a schematic view of the heat retention device.
The attached drawings are as follows: 1-heat insulation material, 2 mould.
Detailed Description
The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The test methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
Example 1
The specific embodiment of the present patent will be described with reference to fig. 1 by taking a passenger car B-pillar as an example.
Step S1, uncoiling and cutting the steel plate, conveying the steel plate to a heating furnace, heating to 950 ℃, and completely austenitizing the steel plate;
and step S2, conveying the heated plate material to a stamping mechanism, and stamping the plate material to obtain the B-pillar part. Controlling the cooling time of the part in a mold with a cooling water channel to be 20s, and taking out the part when the temperature of the part is 250 +/-20 ℃;
and step S3, placing the plate in a mold of a heat preservation device, combining the plate and the mold, preheating the mold at 250 ℃, preserving the heat of the heat preservation device by using asbestos as a heat preservation material for 20min, and placing the part in air after opening the mold to be cooled.
Example 2
The specific embodiment of the present invention is described with reference to fig. 1 by taking a passenger car B-pillar as an example.
Step S1, uncoiling and cutting the steel plate, conveying the steel plate to a heating furnace, heating to 900 ℃, and completely austenitizing the steel plate;
and step S2, conveying the heated plate material to a stamping mechanism, and stamping the plate material to obtain the B-pillar part. Controlling the cooling time of the part in a mold with a cooling water channel to be 4s, and taking out the part when the temperature of the part is 270 +/-20 ℃;
and step S3, placing the plate in a mold of a heat preservation device, combining the mold, preheating the mold at 300 ℃, preserving heat for 30min by using aluminum silicate as a heat preservation material of the heat preservation device, and placing the part in air after opening the mold to be cooled.
Example 3
The specific embodiment of the present patent will be described with reference to fig. 1 by taking a passenger car B-pillar as an example.
Step S1, uncoiling and cutting the steel plate, conveying the steel plate to a heating furnace, heating to 1100 ℃, and completely austenitizing the steel plate;
and step S2, conveying the heated plate material to a stamping mechanism, and stamping the plate material to obtain the B-pillar part. Controlling the cooling time of the part in a mold with a cooling water channel to be 10s, and taking out the part when the temperature of the part is 300 +/-20 ℃;
and step S3, placing the plate in a mold of a heat preservation device, combining the plate and the mold, preheating the mold at 350 ℃, preserving heat for 25min by using asbestos as a heat preservation material of the heat preservation device, and placing the part in air after opening the mold to be cooled.
The tensile strength of the parts prepared in the embodiments 1 to 3 is kept above 1200mpa, the elongation is increased from about 8% to above 15%, and the product of strength and elongation of the same batch of materials is greatly improved.
Claims (8)
1. A method for processing a bainite hot forming steel part is characterized in that: the method comprises the following steps:
s1, unfolding the hot-formed steel coil by using an uncoiler, cutting the steel coil into plates, conveying the plates to a heating furnace by using a conveying mechanism, and heating to 900-1100 ℃ to make the plates fully austenitized;
s2, conveying the heated plate to a stamping mechanism, stamping the plate to obtain a required part, controlling the cooling time of the part in a die with a cooling water channel, enabling the temperature of the part to rapidly pass through a pearlite transformation temperature interval, and taking out the part when the temperature of the part reaches a lower bainite transformation temperature;
and S3, conveying the parts to a heat preservation device, placing the parts in a mold of the heat preservation device, and closing the heat preservation device and preserving heat until the parts are cooled to the bainite transformation finishing temperature.
2. The method of claim 1, wherein: and in the step S2, the cooling time of the part in the mold with the cooling water channel is 4-20S.
3. The method of claim 1, wherein: in the step S2, the lower bainite transformation temperature is 200-450 ℃.
4. The method of claim 1, wherein: in the step S3, the time for closing the mold and preserving heat is 20-30 min, and the heat preservation temperature is 200-450 ℃.
5. The method of claim 1, wherein: the heat preservation device in the step S3 is composed of a mold and a heat preservation material.
6. The method of claim 4, wherein: the mold is preheated to a temperature near the bainite transformation zone.
7. The method of claim 4, wherein: the heat insulation material group is arranged on the outer side of the die, and the cooling speed of the part can be controlled by replacing heat insulation materials with different thicknesses and thermal coefficients.
8. The method of claim 4, wherein: the heat-insulating material is asbestos or aluminum silicate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210555720.9A CN115058558A (en) | 2022-05-20 | 2022-05-20 | Method for processing bainite hot formed steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210555720.9A CN115058558A (en) | 2022-05-20 | 2022-05-20 | Method for processing bainite hot formed steel |
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| Publication Number | Publication Date |
|---|---|
| CN115058558A true CN115058558A (en) | 2022-09-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210555720.9A Pending CN115058558A (en) | 2022-05-20 | 2022-05-20 | Method for processing bainite hot formed steel |
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| Country | Link |
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| CN (1) | CN115058558A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101139645A (en) * | 2007-10-23 | 2008-03-12 | 天津理工大学 | Short-time lower bainite isothermal heat treatment process for industrial 9SiCr steel |
| DE102008022401A1 (en) * | 2008-05-06 | 2009-11-19 | Thyssenkrupp Steel Ag | Method for the production of steel mold part e.g. automobile body with predominantly bainitic structure, comprises providing starting material in the form of a steel plate or a preformed steel part and through-heating the starting material |
| CN104962824A (en) * | 2015-06-24 | 2015-10-07 | 中北大学 | Nano bainitic steel containing proeutectoid ferrite and preparation method of nano bainitic steel |
| CN105568142A (en) * | 2016-03-09 | 2016-05-11 | 桂林电子科技大学 | High-strength and high-tenacity low-alloy wear-resistant steel excavator bucket tooth and preparing method thereof |
| CN112961963A (en) * | 2020-12-25 | 2021-06-15 | 苏州奥维精密机械有限公司 | Preparation process for improving toughness of hot stamping die steel |
| CN112981215A (en) * | 2021-02-02 | 2021-06-18 | 北京科技大学 | Preparation method of niobium-containing nano bainite steel with good thermal stability |
-
2022
- 2022-05-20 CN CN202210555720.9A patent/CN115058558A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101139645A (en) * | 2007-10-23 | 2008-03-12 | 天津理工大学 | Short-time lower bainite isothermal heat treatment process for industrial 9SiCr steel |
| DE102008022401A1 (en) * | 2008-05-06 | 2009-11-19 | Thyssenkrupp Steel Ag | Method for the production of steel mold part e.g. automobile body with predominantly bainitic structure, comprises providing starting material in the form of a steel plate or a preformed steel part and through-heating the starting material |
| CN104962824A (en) * | 2015-06-24 | 2015-10-07 | 中北大学 | Nano bainitic steel containing proeutectoid ferrite and preparation method of nano bainitic steel |
| CN105568142A (en) * | 2016-03-09 | 2016-05-11 | 桂林电子科技大学 | High-strength and high-tenacity low-alloy wear-resistant steel excavator bucket tooth and preparing method thereof |
| CN112961963A (en) * | 2020-12-25 | 2021-06-15 | 苏州奥维精密机械有限公司 | Preparation process for improving toughness of hot stamping die steel |
| CN112981215A (en) * | 2021-02-02 | 2021-06-18 | 北京科技大学 | Preparation method of niobium-containing nano bainite steel with good thermal stability |
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Application publication date: 20220916 |