CN104480397B - A kind of 700MPa grades of Hot Rolling Automobile structural steel and preparation method thereof - Google Patents
A kind of 700MPa grades of Hot Rolling Automobile structural steel and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of ferrous materials engineering, it is related to a kind of high-strength vehicle steel and its manufacture method, is specifically related to a kind of 700MPa grades of Hot Rolling Automobile structural steel and preparation method thereof.A kind of 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.05~0.1%, Si 0.30~0.60%, Mn 0.50~1.00%, Alt 0.02~0.06%, Cr 0.60~1.00%, P≤0.06%, Ti 0.05~0.10%, S≤0.005%, N≤0.006%, balance of Fe and inevitable impurity.The present invention, by adding Cr, Ti and P, strictly controls S, N content on the basis of C Si Mn composition of steel, without the valuable microalloy element of Nb, V, also without precious alloys such as Mo, Ni, significantly reduces cost.
Description
Technical field
The invention belongs to the technical field of ferrous materials engineering, it is related to a kind of high-strength vehicle steel and its manufacture method,
It is specifically related to a kind of 700MPa grades of Hot Rolling Automobile structural steel and preparation method thereof.
Background technology
Day it is becoming tight with the energy, environmental pressure increasingly sharpens, and adds constantly improve of the whole world to legislative work for protecting environment, promotees
Enter automotive technology development center of gravity to develop in terms of energy-saving and environmental protection and security.Mitigate zero with modern technologies and method
The weight of part or vehicle, on the premise of the performance such as ensure safety, realized by loss of weight energy-saving and emission-reduction consumption reduction target into
It is common recognition.
For a long time, both at home and abroad when steel grade of the yield strength in more than 600MPa is obtained more use alloying, it is generally logical
Cross the alloying elements such as addition Mo, Cr, Ni, B to realize, cause the increase of steel product cost；Meanwhile, increasing for alloying element increased
The smelting of steel early stage and the difficulty of later stage recycling.For these factors, have in the prior art by using addition Ti and
The method of Mo obtains hot-rolling high-strength steel, but addition Ti and Mo must have certain proportion, and the intensity of steel can be only achieved
More than 700MPa.The addition of Mo elements, accordingly increased the cost of steel, and its process route complexity, it is necessary to after finish to gauge
Batched after held for some time, influenceed the rhythm of production at scene.At present both at home and abroad high-strength steel sheet using addition Nb, V,
The method production of Ti microalloy elements, based on refined crystalline strengthening or the strengthening mechanism of precipitation strength；Some production costs are higher,
What is had cannot meet the raising requirement that auto parts and components are proposed to fatigue behaviour.
Publication number CN101525717A discloses a kind of 700MPa grade Ti micro-alloyings Ultrafine Grained Steel and its production method,
0.03~0.07%C, Si ＜ 0.30%, 1.00~2.10%Mn, P≤0.02%, 0.10-0.14%Ti, S≤0.008%, in thin strand
A kind of 700MPa grades high-strength steel is obtained on continuous casting and rolling production line, the steel grade employs the composition design of manganese high titanium high, not
Solve the problems, such as that the big performance of titanium steel strength fluctuation high is difficult to stability contorting, impact property when especially Ti content is more than 0.10%
Decline with fatigue behaviour more apparent, it is impossible to meet requirement of the auto parts and components to fatigue high and high impact property.
The A of publication number CN 101768698 disclose a kind of inexpensive yield strength 700MPa grades of Micro Alloying treatment high-strength steel
Plate, it is characterised in that：Contain C in mass：0.05~0.10%；Si：0.1%~0.4%；Mn：1.5~2.0%；P ＜
0.015%；S ＜ 0.01%；Cr：0.3~0.8 %；Ti：0.09~0.15%；Nb：0.04~0.08%；N：＜ 0.005%；
O：＜ 0.002%；Remaining is iron Fe and inevitable impurity, produces more than 700MPa grades of high-strength steel, the patent
The middle composition design compound using manganese chromium alloying high, niobium titanium, its expensive alloying elements addition is larger, and production cost is higher.
Publication number CN101565794A, CN200510100421.2, CN2005110047632.4,
CN2005110047633.9, JP11343536 etc. employ compound Gao Meng, niobium titanium or v n micro alloying and niobium vanadium titanium is multiple
The composition designs such as microalloying are closed, production cost is higher.
Publication No. US20120247606A1, publication date is on October 4th, 2012, a kind of entitled " temperature-controlled rolling
The american documentation literature of the steel plate without the low molybdenum low-alloy high-strength for accelerating cooling ", it discloses a kind of low molybdenum low-alloy content
Steel plate, the basic composition of the steel plate（In terms of weight/mass percentage composition wt%）For：C：0.05~0.07, Mn：1.5~1.7, Ti：
0.01~0.025；Al：0.02~0.04；Nb：0.075~0.1, P≤0.01, S≤0.003, Mo：0.1~0.2, remaining is
Fe and inevitable impurity.Two kinds of more valuable alloys of Mo and Nb are with the addition of in steel plate disclosed in the patent document
Element.
Publication No. US20120247605A1, publication date is on October 4th, 2012, a kind of entitled " temperature-controlled rolling
Without accelerate cooling without molybdenum low-alloy high-strength steel plate " american documentation literature, it discloses a kind of low conjunction without molybdenum element
Golden high intensity steel grade.The weight/mass percentage composition of the steel grade（wt.%）For：C：0.05~0.09%；Mn:1.70~1.95%；Ti：
0.01~0.02%；Al：0.02-0.055%；Nb：0.075~0.1%；P≤0.015%；S≤0.003%；V：0.01~0.03%；
Mo≤0.003%；Remaining is Fe and inevitable other impurities.Although patent document is not added with Mo elements, but is adding
In the case of entering Nb elements, V elements are with the addition of again.
Publication No. US20100212785A1, publication date is on August 26th, 2010, and entitled " one kind has excellent
High pressure hydrogen environment degradation property Hi-Stren steel and its manufacture method " american documentation literature, it is related to a kind of high-strength
Low-alloy steel grade is spent, the weight/mass percentage composition of the chemical element of the steel grade is：C：0.10~0.20%, Si：0.10~0.40%,
Mn：0.50~1.20%, Cr：0.20~0.80%, Cu：0.10~0.50%, Mo：0.10~1.00%, V：0.01~
0.10%, B：0.0005~0.005%, N：≤ 0.01%, surplus is made up of Fe and inevitable impurity.In the patent, though
Nb elements are so not added with, but on the basis of Mo elements are added, also added the expensive alloying elements such as Cu, V.
In view of the high-strength vehicle structural steel requirement higher to fatigue behaviour and impact property and with low cost etc.
Factor,
The present invention is studied chemical composition with when technique, have devised a kind of 700MPa grades of high-strength steel and its life
Production. art, the product of production is suitable to the processing and manufacturing of auto parts and components, particularly has high request to fatigue behaviour and impact property
Part, meet automotive light weight technology development requirement.
The content of the invention
The requirement higher to fatigue behaviour and impact property it is an object of the invention to be directed to high-strength vehicle structural steel
And the factor such as with low cost and a kind of 700MPa grades of Hot Rolling Automobile structural steel and preparation method thereof is provided, the present invention is in C-
On the basis of Si-Mn composition of steel, by adding Cr, Ti and P, S, N content are strictly controlled, without the valuable microalloy unit of Nb, V
Element, also without precious alloys such as Mo, Ni, significantly reduces cost, using cooling controlling and rolling controlling process, obtains tensile strength 700MPa
High-strength vehicle structural steel more than level, it is finally organized as ferrite+bainite structure.The structural steel without Nb,
The elements such as V, Mo, Ni, have saved production cost, and production method also allows for operation.Structural steel of the invention can be widely applied to
The production of automobile structure and reinforcer, meets the light-weighted requirement of auto industry.
The technical scheme is that：A kind of 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight
Chemical composition：C 0.05~0.1%, Si 0.30~0.60%, Mn 0.50~1.00%, Alt 0.02~0.06%, Cr 0.60~
1.00%th, P≤0.06%, Ti 0.05~0.10%, S≤0.005%, N≤0.006%, balance of Fe and inevitable impurity.
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.06~
0.09%th, Si 0.30~0.50%, Mn 0.60~0.9%, Alt 0.02~0.06%, Cr 0.70~0.9%, P 0.03~
0.06%th, Ti 0.05~0.10%, S≤0.005%, N≤0.006%, balance of Fe and inevitable impurity.
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.08%、Si
0.34%th, Mn 0.75%, Alt 0.03%, Cr 0.74%, P 0.045%, Ti 0.078%, S 0.003%, N 0.0033%, surplus
It is Fe and inevitable impurity.
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.058%、Si
0.35%th, Mn 0.63%, Alt 0.034%, Cr 0.69%, P 0.059%, Ti 0.067%, S 0.004%, N.0.0042%, remaining
Measure is Fe and inevitable impurity.
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.066%、Si
0.38%th, Mn 0.75%, Alt 0.041%, Cr 0.65%, P 0.053%, Ti 0.076%, S 0.002%, N0.0026%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.05~0.10%, P≤0.06%, Mn 0.50~1.00%, Si 0.30~0.60%；Calcium line is fed to folder after carrying out LF treatment again
Debris carry out degenerative treatments and control the soft blow time to be not less than 10 minutes, are finally casting continuously to form the thick strands of 90~250mm, strand warp
Cross hot continuous rolling and 700MPa grades of Hot Rolling Automobile structural steel is obtained；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：By heating strand that gained thickness is 90~250mm to 1200~1300 DEG C, soaking time 1~
3 hours, then rolled；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1100~1180 DEG C, finishing temperature 1000~
1100 DEG C, finish rolling stage start rolling temperature is 980~1080 DEG C, and finishing temperature is 800~880 DEG C；Cooled down after the completion of rolling；
（3）Cooling technique：Using cooling speed change cooling technique, 650~700 DEG C, air cooling are cooled to the cooling rate of 50~100 DEG C/s
1~
3S, is then cooled to target coiling temperature and is batched with the cooling rate of 50~200 DEG C/s；
（4）Coiling technique：Coiling temperature is 250~450 DEG C.
The coiling temperature of the coiling technique is 350~450 DEG C.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, including molten iron pretreatment；Converter smelting；At LF
Reason；Continuous casting；Hot continuous rolling；The hot continuous rolling process is：
（1）Heating technique：It is the heating strand of 135mm to 1270 DEG C, soaking time 2 hours, Ran Houjin by gained thickness
Row rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1170 DEG C, 1090 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 32mm is made, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 880 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 686 DEG C are cooled to the cooling rate of 78 DEG C/S, air cooling 3S, then with
The cooling rate of 82 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 416 DEG C.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, including molten iron pretreatment；Converter smelting；At LF
Reason；Continuous casting；Hot continuous rolling；The hot continuous rolling process is：
（1）Heating technique：It is the heating strand of 135mm to 1260 DEG C by gained thickness, soaking time 2.5 hours, then
Carry out
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1160 DEG C, 1070 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 34mm is made, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 870 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 673 DEG C are cooled to the cooling rate of 67 DEG C/S, air cooling 2S, then with
The cooling rate of 62 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 352 DEG C.
Beneficial effects of the present invention are：Each alloys producing is as follows in the present invention：C：Improve steel intensity it is important
Element, C content too low then intensity is not enough, and C content too high welding performance and forming property deteriorate, therefore control 0.05~
0.10%, preferably 0.06~0.09%.
Si：Deoxidant element, while playing solution strengthening effect in steel, the too low reinforcing effect of content is too weak, content Tai Gaobiao
Face quality is difficult to control, therefore control is in 0.30~0.60%, preferably 0.30~0.50%.
Mn：Improve yield strength and quenching degree, the too low intensity for causing body body stability difficult to understand and steel is not enough, too high to make steel
Plasticity and weldability decline, therefore control in 0.50~1.00%, preferably 0.60~0.90%.
S：Impurity element in steel, larger to formability and Influence of Fatigue Properties, content is more low better.
P：Solution strengthening element, adds appropriate P to promote ferritic generation and keeps intensity and moulding good flat
Weighing apparatus, therefore control is in≤0.06%, preferably 0.03~0.06%.
Cr：Improve the element of quenching degree, be conducive to the stabilization of austenite, too high then ductility to be deteriorated, too low then quenching degree
Reduce, intensity is not enough, therefore control is in 0.60~1.00%, preferably 0.70~0.90%.
Alt:Deoxidant element, can reduce the oxide in steel and be mingled with and pure steel, be conducive to improving the formability of steel plate
Energy；Too high levels will cause ductility to be deteriorated, therefore control is 0.02~0.06%.
700MPa grades of Hot Rolling Automobile structural steel of present invention production, yield strength >=650MPa, tensile strength >=
700MPa, elongation percentage >=16%, with intensity higher, plastotype and formability, preferable extensibility, weldability, clod wash
Etc. performance, it is suitable to the processing and manufacturing of the automobile components such as automobile frame, structural member and reinforcer, meets automotive light weight technology
Demand for development.It is particularly suitable for the production and processing of the automobile structure and reinforcer of requirement high intensity and high fatigue property.
Specific embodiment
Below by embodiment, the present invention will be described in detail.
Embodiment 1
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.08%、Si
0.34%th, Mn 0.75%, Alt 0.03%, Cr 0.74%, P 0.045%, Ti 0.078%, S 0.003%, N 0.0033%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.08%、P 0.045%、Mn 0.75% 、Si 0.34% ；Hello calcium line carries out degenerative treatments simultaneously to field trash after carrying out LF treatment again
The control soft blow time is not less than 10 minutes, is finally casting continuously to form the thick strands of 135mm, and strand is obtained 700MPa grades of heat by hot continuous rolling
Roll vehicle structure steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 135mm to 1260 DEG C, soaking time 2 hours, Ran Houjin by gained thickness
OK
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1180 DEG C, 1100 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 32mm is made, finish rolling stage start rolling temperature is 1070 DEG C, and finishing temperature is 880 DEG C；Rolling completes laggard
Row cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 692 DEG C are cooled to the cooling rate of 79 DEG C/S, air cooling 1s, then with
The cooling rate of 136 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 392 DEG C, gained steel plate finished product thickness 1.8mm.
The yield strength of the resulting structures steel of embodiment 1 is 692MPa, and tensile strength is 758MPa, and elongation percentage is
18%。
Embodiment 2
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.058%、Si
0.35%th, Mn 0.63%, Alt 0.034%, Cr 0.69%, P 0.059%, Ti 0.067%, S 0.004%, N0.0042%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.058%、P 0.059%、Mn 0.63% 、Si 0.35% ；Hello calcium line carries out degenerative treatments to field trash after carrying out LF treatment again
And control the soft blow time to be not less than 10 minutes, and the thick strands of 135mm are finally casting continuously to form, strand is obtained 700MPa grades by hot continuous rolling
Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 135mm to 1270 DEG C, soaking time 2 hours, Ran Houjin by gained thickness
OK
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1170 DEG C, 1090 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 32mm is made, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 880 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 686 DEG C are cooled to the cooling rate of 78 DEG C/S, air cooling 3s, then with
The cooling rate of 82 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 416 DEG C.Gained steel plate finished product thickness 2mm.
The yield strength of the resulting structures steel of embodiment 2 is 689MPa, and tensile strength is 773MPa, and elongation percentage is
17%。
Embodiment 3
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.066%、Si
0.38%th, Mn 0.75%, Alt 0.041%, Cr 0.65%, P 0.053%, Ti 0.076%, S 0.002%, N0.0026%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.066%、P 0.053%、Mn 0.75% 、Si 0.38% ；Hello calcium line carries out degenerative treatments to field trash after carrying out LF treatment again
And control the soft blow time to be not less than 10 minutes, and the thick strands of 135mm are finally casting continuously to form, strand is obtained 700MPa grades by hot continuous rolling
Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 135mm to 1260 DEG C by gained thickness, soaking time 2.5 hours, then
Carry out
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1160 DEG C, 1070 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 34mm is made, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 870 DEG C；Rolling completes laggard
Row cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 673 DEG C are cooled to the cooling rate of 67 DEG C/S, air cooling 2s, then with
The cooling rate of 62 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 352 DEG C.Gained steel plate finished product thickness 4mm.
The yield strength of the resulting structures steel of embodiment 3 is 672MPa, and tensile strength is 757MPa, and elongation percentage is 19%.
Embodiment 4
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.073%、Si
0.48%th, Mn 0.76%, Alt 0.031%, Cr 0.72%, P 0.043%, Ti 0.056%, S 0.003%, N0.0029%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.073%、P 0.043%、Mn 0.76% 、Si 0.48% ；Hello calcium line carries out degenerative treatments to field trash after carrying out LF treatment again
And control the soft blow time to be not less than 10 minutes, and the thick strands of 135mm are finally casting continuously to form, strand is obtained 700MPa grades by hot continuous rolling
Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 135mm to 1250 DEG C, soaking time 2 hours, Ran Houjin by gained thickness
OK
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1160 DEG C, 1060 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 34mm is made, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 860 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 667 DEG C are cooled to the cooling rate of 61 DEG C/S, air cooling 2s, then with
The cooling rate of 67 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 376 DEG C.Gained steel plate finished product thickness 5mm.
The yield strength of the resulting structures steel of embodiment 4 is 666MPa, and tensile strength is 746MPa, and elongation percentage is 20%.
Embodiment 5
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.084%、Si
0.40%th, Mn 0.87%, Alt 0.043%, Cr 0.77%, P 0.036%, Ti 0.092%, S 0.001%, N0.0034%, surplus
It is Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.084%、P 0.036%、Mn 0.87% 、Si 0.40% ；Hello calcium line carries out degenerative treatments to field trash after carrying out LF treatment again
And control the soft blow time to be not less than 10 minutes, and the thick strands of 135mm are finally casting continuously to form, strand is obtained 700MPa grades by hot continuous rolling
Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 135mm to 1250 DEG C, soaking time 2 hours, Ran Houjin by gained thickness
OK
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1180 DEG C, 1060 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 38mm is made, finish rolling stage start rolling temperature is 1030 DEG C, and finishing temperature is 840 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 671 DEG C are cooled to the cooling rate of 58 DEG C/S, air cooling 1s, then with
The cooling rate of 57 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 346 DEG C.Gained steel plate finished product thickness 6mm.
The yield strength of the resulting structures steel of embodiment 5 is 662MPa, and tensile strength is 741MPa, and elongation percentage is
18.5%。
Embodiment 6
The 700MPa grades of Hot Rolling Automobile structural steel, including following percentage by weight chemical composition：C 0.095%、
Si 0.45%, Mn 0.92%, Alt 0.028%, Cr 0.88%, P 0.052%, Ti 0.088%, S 0.001%, N0.0045%,
Balance of Fe and inevitable impurity.
The preparation method of the 700MPa grades of Hot Rolling Automobile structural steel, comprises the following steps：Molten iron is de- by KR first
Sulphuring treatment；Then routinely smelted by converter, the weight percent content of control molten steel terminal C, P, Mn, Si is respectively：C
0.095%、P 0.052%、Mn 0.92% 、Si 0.45% ；Hello calcium line carries out degenerative treatments to field trash after carrying out LF treatment again
And control the soft blow time to be not less than 10 minutes, and the thick strands of 150mm are finally casting continuously to form, strand is obtained 700MPa grades by hot continuous rolling
Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：It is the heating strand of 150mm to 1240 DEG C by gained thickness, soaking time 2.5 hours, then
Carry out
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction
It is >=70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature is 1130 DEG C, 1030 DEG C of finishing temperature, and 3 passages are rolled
The middle base of 45mm is made, finish rolling stage start rolling temperature is 990 DEG C, and finishing temperature is 820 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 656 DEG C are cooled to the cooling rate of 52 DEG C/S, air cooling 1s, then with
The cooling rate of 56 DEG C/S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 307 DEG C.Gained steel plate finished product thickness 8mm.
The yield strength of the resulting structures steel of embodiment 6 is 656MPa, and tensile strength is 738MPa, and elongation percentage is
17.5%。
A kind of 700MPa grades of Hot Rolling Automobile structural steel cost of the invention is relatively low, forming property and excellent weldability, fits
In the processing and manufacturing of auto parts and components, particularly there are the part of high request, manufacture of the invention to fatigue behaviour and impact property
Method is workable, it is easy to accomplish industrialized production, with application value higher.
Claims (4)
1. a kind of 700MPa grades of Hot Rolling Automobile structural steel, it is characterised in that the chemical composition including following percentage by weight：C
0.058%、Si 0.35%、Mn 0.63%、Alt 0.034%、Cr 0.69%、P 0.059%、Ti 0.067% 、S 0.004%、N
0.0042%, balance of Fe and inevitable impurity.
2. a kind of 700MPa grades of Hot Rolling Automobile structural steel, it is characterised in that the chemical composition including following percentage by weight：C
0.066%、Si 0.38%、Mn 0.75%、Alt 0.041%、Cr 0.65%、P 0.053%、Ti 0.076%、S 0.002%、N
0.0026%, balance of Fe and inevitable impurity.
3. the 700MPa grades of preparation method of Hot Rolling Automobile structural steel described in a kind of claim 1, comprises the following steps：Iron first
Water is by KR desulfurization process；Then routinely smelted by converter, the weight percent content point of control molten steel terminal C, P, Mn, Si
It is not：C 0.058%、P 0.059%、Mn 0.63% 、Si 0.35% ；Hello calcium line becomes to field trash after carrying out LF treatment again
Property process and control the soft blow time to be not less than 10 minutes, be finally casting continuously to form the thick strands of 135mm, strand is obtained by hot continuous rolling
700MPa grades of Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：By gained thickness for 135mm heating strand to 1270 DEG C, then soaking time 2 hours is carried out
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction for >=
70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature be 1170 DEG C, 1090 DEG C of finishing temperature, 3 passes into
The middle base of 32mm, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 880 DEG C；Carried out after the completion of rolling
Cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 686 DEG C are cooled to the cooling rate of 78 DEG C/S, air cooling 3s, then with 82 DEG C/
The cooling rate of S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 416 DEG C.
4. the 700MPa grades of preparation method of Hot Rolling Automobile structural steel described in a kind of claim 2, comprises the following steps：Iron first
Water is by KR desulfurization process；Then routinely smelted by converter, the weight percent content point of control molten steel terminal C, P, Mn, Si
It is not：C 0.066%、P 0.053%、Mn 0.75% 、Si 0.38% ；Hello calcium line becomes to field trash after carrying out LF treatment again
Property process and control the soft blow time to be not less than 10 minutes, be finally casting continuously to form the thick strands of 135mm, strand is obtained by hot continuous rolling
700MPa grades of Hot Rolling Automobile structural steel；Wherein described hot continuous rolling includes following technique：
（1）Heating technique：By gained thickness for 135mm heating strand to 1260 DEG C, then soaking time 2.5 hours is carried out
Rolling；
（2）Rolling mill practice：Rolled using two-stage control, wherein rough rolling step single pass reduction ratio >=20%, total reduction for >=
70%, finish rolling stage reduction ratio is >=75%；Rough rolling step start rolling temperature be 1160 DEG C, 1070 DEG C of finishing temperature, 3 passes into
The middle base of 34mm, finish rolling stage start rolling temperature is 1060 DEG C, and finishing temperature is 870 DEG C；Rolling completes laggard
Row cooling；
（3）Cooling technique：Using cooling speed change cooling technique, 673 DEG C are cooled to the cooling rate of 67 DEG C/S, air cooling 2s, then with 62 DEG C/
The cooling rate of S is cooled to target coiling temperature and is batched；
（4）Coiling technique：Coiling temperature is 352 DEG C.
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| CN109161797B (en) * | 2018-09-06 | 2020-11-03 | 邯郸钢铁集团有限责任公司 | Lightweight fatigue-resistant hot-rolled dual-phase wheel steel and production method thereof |
| CN109023109B (en) * | 2018-09-26 | 2019-10-25 | 武汉钢铁有限公司 | Using the 700MPa grade thin gauge Hot Rolling Automobile structural steel and method of short route production |
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| CN101528969A (en) * | 2006-10-30 | 2009-09-09 | 蒂森克虏伯钢铁股份公司 | Method for manufacturing flat steel products from a steel forming a complex phase structure |
| CN103510008A (en) * | 2013-09-18 | 2014-01-15 | 济钢集团有限公司 | Hot rolling ferrite/bainite high strength steel plate and manufacturing method thereof |
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| JP5594438B2 (en) * | 2011-11-08 | 2014-09-24 | Ｊｆｅスチール株式会社 | High tensile hot rolled galvanized steel sheet and method for producing the same |
| CN103088258A (en) * | 2013-01-23 | 2013-05-08 | 马鞍山钢铁股份有限公司 | Five hundred and ninety Mpa-grade dual-phase steel and production method thereof |
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| CN103510008A (en) * | 2013-09-18 | 2014-01-15 | 济钢集团有限公司 | Hot rolling ferrite/bainite high strength steel plate and manufacturing method thereof |
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