CN109868421A - A kind of production method improving hot rolling DP780 steel yield tensile ratio and reaming performance - Google Patents
A kind of production method improving hot rolling DP780 steel yield tensile ratio and reaming performance Download PDFInfo
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- CN109868421A CN109868421A CN201910256363.4A CN201910256363A CN109868421A CN 109868421 A CN109868421 A CN 109868421A CN 201910256363 A CN201910256363 A CN 201910256363A CN 109868421 A CN109868421 A CN 109868421A
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Abstract
The invention discloses a kind of production methods for improving hot rolling DP780 steel yield tensile ratio and reaming performance, it is on the basis of the Design of Chemical Composition of existing hot rolling DP780 steel, pass through the technological parameter of control slab heating process, hot-rolled process, cooling and coiling process, so that Martensite Volume Fraction >=50.0% in microscopic structure, 5.0 μm of the equal < of crystallite dimension, average grain size≤3.5 μm.According to yield tensile ratio >=0.74 of the hot rolling DP780 steel of production method provided by the present invention preparation, hole expansibility >=50%, elongation percentage (A80) reaches 16.5% or more simultaneously, (A50) reach 19.9% or more, it requires especially suitable for thickness specification as 2.0~6.0mm and has good surface quality and drawing feature, while having the automobiles components such as reaming flange and the wheel of high-strength thinned requirement.
Description
Technical field
The invention belongs to automobile hot-rolling high-strength steel technical fields, and in particular to a kind of raising hot rolling DP780 steel yield tensile ratio
With the production method of reaming performance.
Background technique
The fast development of auto industry forcefully pushes Chinese national economy to realize that high speed develops in recent years, but by
This high energy consumption and maximum discharge for generating, serious ground contamination environment, many negative effects are generated to people's daily life.
It can be seen that realize the sustainable development of auto industry, it is necessary to solve the problems, such as energy-saving and emission-reduction, low-carbon environment-friendly, this is also each
State's auto industry faces the matter of utmost importance to be solved, while but also people Hyundai Motor is proposed it is safe and environment-friendly, easypro
Suitable, energy conservation should realize lightweight in the new demand of one, also guarantee vehicle performance simultaneously, therefore whole by design optimization
Bassinet structure and the various new materials of application, new process become the target pursued when researching and developing new model of Automobile Enterprises and lead
To, and be directed to 780MPa rank hot rolling DP steel, research and development and designer propose new demand, do not require nothing more than have it is good
Surface quality and drawing feature, while having reaming flange and high-strength thinned requirement.Traditional hot rolling DP780 steel has low yield strength ratio
Feature is unable to satisfy reaming, flange and high-strength thinned requirement during shaping, micro-crack inevitably occurs very
To the defects of cracking.As it can be seen that on the basis of the Design of Chemical Composition of existing 780MPa rank hot rolling DP steel, by regulating and controlling each process
The key process parameter of section, produces high-yield-ratio and hole expansibility, is provided simultaneously with the heat of good surface quality and drawing feature
DP780 steel is rolled, is those skilled in the art's technical problem urgently to be resolved.Skill disclosed in existing 780MPa rank hot rolling DP steel
Art is the hot rolling DP780 steel for low yield strength ratio (< 0.70), carries out explaining for production method, processing method or manufacturing method
It is bright.Such as CN 107829027A discloses a kind of thin gauge 780MPa grades of dual phase steels and its processing method, yield tensile ratio is 0.53~
0.59, and yield tensile ratio >=0.74 of the present invention；CN 102912244A discloses a kind of tensile strength 780MPa grades of hot rolling biphase plates
And its manufacturing method, yield tensile ratio are 0.59~0.66；CN 104357744A discloses a kind of tensile strength >=780MPa grades of hot rolling
Dual phase steel and production method, yield tensile ratio are 0.55~0.68；It is double that CN 105925905A discloses the 780MPa grades of hot rollings of Nb-Ti system
Xiang Gang and its production method, yield tensile ratio are 0.51~0.59；It is double that CN 105838997A discloses the 780MPa grades of hot rollings of Si-Mn system
Xiang Gang and its production method, yield tensile ratio are 0.51~0.60；It is double that CN 105779874A discloses the 780MPa grades of hot rollings of Cr-Nb system
Xiang Gang and its production method, yield tensile ratio are 0.52~0.59；It is double that CN 106834915A discloses the 800MPa grades of hot rollings of 2~4mm thickness
Xiang Gang and its processing method, yield tensile ratio are 0.66~0.68.CN 105925892A discloses a kind of 780MPa grades of hot rolling high-chambering
Dual phase steel and its manufacturing method, yield tensile ratio are 0.79~0.84, elongation percentage 16.0~17.5%, hole expansibility 42~50%.And this
The reaming of invention hot rolling DP780 steel product and ductility are more excellent, wherein hole expansibility >=50%, while elongation percentage (A80) reach
16.5% or more, (A50) reach 19.9% or more.In addition, 0.8 must be added in the ingredient design of CN 105925892A~
1.8%Si, to promote ferritic formation and play its invigoration effect, but add Si that strip surface quality, this hair can be deteriorated
It is bright that Si is reduced to 0.40~0.70%, it can avoid the adverse effect that Si element generates Surfaces of Hot Rolled Strip.
Summary of the invention
The technical problem to be solved by the present invention is to pass through control on the basis of the Design of Chemical Composition of existing hot rolling DP780 steel
Making sheet base heating process, hot-rolled process, cooling and coiling process technological parameter, produce high-yield-ratio and reaming
Rate is provided simultaneously with the hot rolling DP780 steel of good surface quality and drawing feature, to solve traditional low yield strength ratio hot rolling DP780
Steel is unable to satisfy reaming, flange and high-strength thinned requirement during shaping, and micro-crack inevitably occurs even
The problem of the defects of cracking.
In order to solve the above technical problems, of the invention provide a kind of raising hot rolling DP780 steel yield tensile ratio and reaming performance
Production method, carry out in accordance with the following methods control each process section technological parameter:
(1) steel making working procedure: the chemical component of steel billet includes C:0.08~0.12% by weight percentage, and Si:0.40~
0.70%, Mn:1.30~1.60%, Alt:0.040~0.070%, Nb:0.04~0.07%, Mo:0.10~0.30%, and
N≤0.006%, P≤0.008%, S≤0.006%, O≤0.0030% are limited, surplus is Fe and other are inevitably miscellaneous
Matter；
(2) heating of plate blank process: by heating steel billet, it is 1190~1220 DEG C that soaking section temperature, which is arranged, soaking time 20~
30min, total time inside furnace are about 230min；
(3) hot-rolled process: roughing mill and the sub-distribution of finishing mill road and each percentage pass reduction are by level two roughing setting up mould
Type calculates；950~980 DEG C of roughing outlet temperature, wherein 2.00mm≤hot-rolled finished product thickness < 4.00mm roughing outlet base is thick
For 40mm, it is 45mm, 5.00mm≤hot-rolled finished product thickness that 4.00mm≤hot-rolled finished product thickness < 5.00mm roughing, which exports base thickness,
The roughing outlet base thickness of≤6.00mm is 50mm；Finish rolling finishing temperature (Ar3+ 5 DEG C)~(Ar3+ 35 DEG C), and guarantee finishing rolling mill
Last two percentage pass reduction >=10%；
(4) it cooling process: is taken first after finish rolling and rolls rear leading portion ultra-rapid cooling technique, with the cold of >=100 DEG C/s
Speed is quickly cooled to 700~730 DEG C；Then it is air-cooled to temperature to 660~690 DEG C；Finally be cooled to the cooling rate of >=80 DEG C/s≤
200℃；
(5) coiling process: it will be cooled to the steel strip coiling of≤200 DEG C of temperature into coil of strip, cooled to room temperature obtains
Finished steel coils of the invention.
A kind of production method improving hot rolling DP780 steel yield tensile ratio and reaming performance of the present invention, passes through control panel
Base heating process, hot-rolled process, cooling and coiling process technological parameter so that Martensite Volume Fraction in microscopic structure >=
50.0%, 5.0 μm of the equal < of crystallite dimension, average grain size≤3.5 μm.
The thickness specification of hot rolling DP780 steel product of the present invention is 2.0~6.0mm, and surface quality is good, yield tensile ratio
>=0.74, hole expansibility >=50%, while elongation percentage (A80) reach 16.5% or more, (A50) reach 19.9% or more.
The beneficial effects of adopting the technical scheme are that the technical problem to be solved by the present invention is to be existing
On the basis of the Design of Chemical Composition of hot rolling DP780 steel, pass through control slab heating process, hot-rolled process, cooling and coiling process
Technological parameter, produce high-yield-ratio (>=0.74) and hole expansibility (>=50%), be provided simultaneously with good surface quality and drawing
Prolong feature (A80>=16.5%, A50>=19.9%) hot rolling DP780 steel is being added with solving traditional low yield strength ratio hot rolling DP780 steel
It is unable to satisfy reaming, flange and high-strength thinned requirement in work forming process, micro-crack even cracking etc. inevitably occurs
The problem of defect.It requires especially suitable for 780MPa rank, thickness specification as 2.0~6.0mm and has good surface quality
With drawing feature, while there are the automobiles components such as reaming flange and the wheel of high-strength thinned requirement.
Detailed description of the invention
Fig. 1 is the hot rolling DP780 steel micro-organization chart of technique 1-II preparation in the embodiment of the present invention 1；
Fig. 2 is that the hot rolling DP780 steel EBSD crystallite dimension of technique 1-II preparation in the embodiment of the present invention 1 analyzes result.
Specific embodiment
It is that a specific embodiment of the invention is described in further detail, but embodiments of the present invention are not limited to below
This.
Examples 1 to 3: a kind of production method improving hot rolling DP780 steel yield tensile ratio and reaming performance of the present invention,
As described below.
The chemical component of steel billet includes C:0.08~0.12%, Si by weight percentage in the embodiment of the present invention 1~3:
0.40~0.70%, Mn:1.30~1.60%, Alt:0.040~0.070%, Nb:0.04~0.07%, Mo:0.10~
0.30%, and N≤0.006% is limited, P≤0.008%, S≤0.006%, O≤0.0030%, surplus is Fe and other can not
The tapping ladle chemistry of steel billet is as shown in table 1 in the impurity specific embodiment 1~3 avoided, and steel billet is with a thickness of 230mm.
The practical smelting ingredient (mass percent, %) of 1 embodiment of table
The technological parameter of control each process section is carried out in the embodiment of the present invention 1~3 in accordance with the following methods:
(1) heating of plate blank process: by heating steel billet, it is 1190~1220 DEG C that soaking section temperature, which is arranged, soaking time 20~
30min, total time inside furnace are about 230min；
(2) hot-rolled process: roughing mill and the sub-distribution of finishing mill road and each percentage pass reduction are by level two roughing setting up mould
Type calculates；950~980 DEG C of roughing outlet temperature, wherein 2.00mm≤hot-rolled finished product thickness < 4.00mm roughing outlet base is thick
For 40mm, it is 45mm, 5.00mm≤hot-rolled finished product thickness that 4.00mm≤hot-rolled finished product thickness < 5.00mm roughing, which exports base thickness,
The roughing outlet base thickness of≤6.00mm is 50mm；Finish rolling finishing temperature (Ar3+ 5 DEG C)~(Ar3+ 35 DEG C), and guarantee finishing rolling mill
Last two percentage pass reduction >=10%；
(3) it cooling process: is taken first after finish rolling and rolls rear leading portion ultra-rapid cooling technique, with the cold of >=100 DEG C/s
Speed is quickly cooled to 700~730 DEG C；Then it is air-cooled to temperature to 660~690 DEG C；Finally be cooled to the cooling rate of >=80 DEG C/s≤
200℃；
(4) coiling process: it will be cooled to the steel strip coiling of≤200 DEG C of temperature into coil of strip, cooled to room temperature obtains
Finished steel coils of the invention.
In the embodiment of the present invention 1~3, the A that is measured by dilatometryr3It is respectively as follows: 793 DEG C, 805 DEG C, 795 DEG C.
The specific controlled rolling and cooling process parameter of the embodiment of the present invention 1~3 in actual production is as shown in table 2.
The main technique control parameter of 2 embodiment of table
Microscopic examination and Mechanics Performance Testing, test and analysis are carried out to the hot rolling DP780 steel sampling being prepared
As a result 3 are specifically shown in Table.By the technological parameter of control slab heating process, hot-rolled process, cooling and coiling process, so that micro-
Martensite Volume Fraction >=50.0% in tissue, 5.0 μm of the equal < of crystallite dimension, average grain size≤3.5 μm.
The mechanical property and microscopic structure volume fraction of 3 embodiment of table
Attached drawing 1 is the hot rolling DP780 steel micro-organization chart of technique 1-II preparation in the embodiment of the present invention 1, by ferrite and
Second phase martensitic structure forms, wherein martensite accounting 50.3%；Attached drawing 2 is technique 1-II preparation in the embodiment of the present invention 1
Hot rolling DP780 steel EBSD crystallite dimension analyze as a result, 4.35 μm of the equal < of crystallite dimension, average grain size is about 3.2 μm.
Technology disclosed in existing 780MPa rank hot rolling DP steel is the hot rolling for low yield strength ratio (< 0.70)
DP780 steel carries out illustrating for production method, processing method or manufacturing method, is shown in Table 3, CN 107829027A, CN
102912244A、CN 104357744A、CN 105925905A、CN 105838997A、CN 105779874A、CN
106834915A。
CN 105925892A discloses a kind of 780MPa grades of hot rolling high-chambering dual phase steel and its manufacturing method, yield tensile ratio are
0.79~0.84, elongation percentage 16.0~17.5%, hole expansibility 42~50%.And the reaming of hot rolling DP780 steel product of the present invention and
Ductility is more excellent, wherein hole expansibility >=50%, while elongation percentage (A80) reach 16.5% or more, (A50) reach 19.9% with
On.In addition, CN 105925892A ingredient design in must add 0.8~1.8%Si, with promote it is ferritic formation and
Its invigoration effect is played, but add Si to deteriorate strip surface quality, Si is reduced to 0.40~0.70% by the present invention, can avoid
The adverse effect that Si element generates Surfaces of Hot Rolled Strip.
Compared to more existing public technology, mechanical experimental results show to prepare according to production method provided by the invention
Obtained hot rolling DP780 steel, surface quality is good, tensile strength > 780MPa (actual test result is 786~866MPa)；?
When yield tensile ratio is improved to 0.74 or more, hole expansibility can guarantee >=50%, while elongation percentage (A80) reach 16.5% or more, (A50)
Reach 19.9% or more, see Table 3 for details.
The above described is only a preferred embodiment of the present invention, being not that the invention has other forms of limitations, appoint
What those skilled in the art changed or be modified as possibly also with the technology contents of the disclosure above equivalent variations etc.
It imitates embodiment and is applied to other fields, but without departing from the technical solutions of the present invention, according to the technical essence of the invention
Any simple modification, equivalent variations and remodeling to the above embodiments, still fall within the protection scope of technical solution of the present invention.
Claims (3)
1. it is a kind of improve hot rolling DP780 steel yield tensile ratio and reaming performance production method, it is characterised in that in accordance with the following methods into
The technological parameter of row control each process section:
(1) steel making working procedure: the chemical component of steel billet includes C:0.08~0.12% by weight percentage, Si:0.40~0.70%,
Mn:1.30~1.60%, Alt:0.040~0.070%, Nb:0.04~0.07%, Mo:0.10~0.30%, and limit N≤
0.006%, P≤0.008%, S≤0.006%, O≤0.0030%, surplus are Fe and other inevitable impurity；
(2) heating of plate blank process: by heating steel billet, it is 1190~1220 DEG C that soaking section temperature, which is arranged, soaking time 20~
30min, total time inside furnace are about 230min；
(3) hot-rolled process: roughing mill and the sub-distribution of finishing mill road and each percentage pass reduction are by level two roughing setting up model meter
It calculates；950~980 DEG C of roughing outlet temperature, wherein 2.00mm≤hot-rolled finished product thickness < 4.00mm roughing outlet base thickness be
40mm, 4.00mm≤hot-rolled finished product thickness < 5.00mm roughing export base thickness be 45mm, 5.00mm≤hot-rolled finished product thickness≤
The roughing outlet base thickness of 6.00mm is 50mm；Ar3+5 DEG C~Ar3+35 DEG C of finish rolling finishing temperature, and guarantee finishing rolling mill last two
Percentage pass reduction >=10%；
(4) cooling process: taking first after finish rolling and roll rear leading portion ultra-rapid cooling technique, fast with the cooling rate of >=100 DEG C/s
Speed is cooled to 700~730 DEG C；Then it is air-cooled to temperature to 660~690 DEG C；Finally≤200 are cooled to the cooling rate of >=80 DEG C/s
℃；
(5) coiling process: it will be cooled to the steel strip coiling of≤200 DEG C of temperature into coil of strip, cooled to room temperature obtains this hair
Bright finished steel coils.
2. a kind of production method for improving hot rolling DP780 steel yield tensile ratio and reaming performance according to claim 1, feature
It is, by the technological parameter of control slab heating process, hot-rolled process, cooling and coiling process, so that horse in microscopic structure
Family name's body volume fraction >=50.0%, 5.0 μm of the equal < of crystallite dimension, average grain size≤3.5 μm.
3. a kind of production method for improving hot rolling DP780 steel yield tensile ratio and reaming performance according to claim 1, feature
It is, the thickness specification of the hot rolling DP780 steel product is 2.0~6.0mm, and surface quality is good, yield tensile ratio >=0.74, reaming
Rate >=50%, while elongation percentage A80 reaches 16.5% or more, A50 and reaches 19.9% or more.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114507821A (en) * | 2022-02-21 | 2022-05-17 | 山东钢铁集团日照有限公司 | One-steel multi-stage hot-rolled high-hole-expansion steel and production process thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108642387A (en) * | 2018-05-24 | 2018-10-12 | 山东钢铁集团日照有限公司 | A kind of the hot-rolled transformation induction plasticity steel and its production method of steel multistage |
| CN109321827A (en) * | 2018-10-26 | 2019-02-12 | 山东钢铁集团日照有限公司 | A method of producing the economical hot rolling DP780 steel of different yield strength ranks |
-
2019
- 2019-04-01 CN CN201910256363.4A patent/CN109868421A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108642387A (en) * | 2018-05-24 | 2018-10-12 | 山东钢铁集团日照有限公司 | A kind of the hot-rolled transformation induction plasticity steel and its production method of steel multistage |
| CN109321827A (en) * | 2018-10-26 | 2019-02-12 | 山东钢铁集团日照有限公司 | A method of producing the economical hot rolling DP780 steel of different yield strength ranks |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114507821A (en) * | 2022-02-21 | 2022-05-17 | 山东钢铁集团日照有限公司 | One-steel multi-stage hot-rolled high-hole-expansion steel and production process thereof |
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Application publication date: 20190611 |