CN105088068B - A kind of 500MPa grades of automotive frame coated steel and its ultrafast cold production method - Google Patents

A kind of 500MPa grades of automotive frame coated steel and its ultrafast cold production method Download PDF

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CN105088068B
CN105088068B CN201510545348.3A CN201510545348A CN105088068B CN 105088068 B CN105088068 B CN 105088068B CN 201510545348 A CN201510545348 A CN 201510545348A CN 105088068 B CN105088068 B CN 105088068B
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steel
control
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CN105088068A (en
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刘斌
刘永前
王立新
贺啸秋
赵江涛
王孟
杨海林
彭涛
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Wuhan Iron and Steel Co Ltd
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Wuhan Iron and Steel Group Corp
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Abstract

A kind of 500MPa grades of automotive frame coated steel, its chemical composition and wt% are:C:0.06 ~ 0.09%, Si≤0.025%, Mn:1.10 ~ 1.29%, P≤0.015%, S≤0.006%, Als:0.020 ~ 0.060%, Nb:0.025~0.034%;Production stage:Enter argon station Argon after converter smelting;Tap and be casting continuously to form after base to heating strand;It is segmented hot rolling;Section cooling is carried out using the speed type of cooling is become;Batch;Finishing and rear process.The present invention is under relatively low design of alloy, using ultra-rapid cooling and sub-sectional cooling, the coating beam steel produced its there is excellent surface quality and platability, galvanizing production can directly be carried out, and the dent resistance of steel plate, coating adhesion is further enhanced, with good surface quality.

Description

A kind of 500MPa grades of automotive frame coated steel and its ultrafast cold production method
Technical field
The present invention relates to a kind of automobile steel and production method, a kind of 500MPa grades of automotive frame coating is specifically belonged to Steel and its ultrafast cold production method.
Background technology
Coating is used widely with hot-rolled steel for the higher automotive frame of surface quality requirements.Hot-dip galvanizing sheet steel table The characteristics of face has coating light, uniform color, good durability and aesthetic property;Meanwhile, the part such as automotive frame is also required Steel have good dent resistance, and should have high-yield-ratio.
At present, with regard to its beam steel still in the rank steel grade such as Q345, Q235, then in such steel grade surface hot galvanized layer. Due to continuing to develop for auto industry, it can not meet the requirement of manufacture high-strength vehicle structural member and its surface galvanizing. Therefore, steel industry manufacturer is actively developing the research and development of the parties concerned.
In the prior art, the cooling for steel plate is cooled to requirement using a relatively low or conventional stable cooling velocity Temperature, a large amount of analysis and research through the applicant, the steel plate produced using this type of cooling, for intensity as defined in reaching and group Knit, generally require to add more alloying element, production cost is higher.
Through preliminary search, Chinese Patent Application No. is CN200910063433.0 document, discloses a kind of yield strength The production method of 460MPa grades of coating hot-rolled structural steels, it includes in turn including the following steps:Steel-making, continuous casting, heating of plate blank, Hot continuous rolling, section cooling, batch;It is characterized in that the chemical analysis and percentage by weight in steelmaking process are:C:0.05~ 0.10%;Si≤0.04;Mn:1.30~1.65%;P≤0.030%;S≤0.012%;Als:0.01~0.06%;Nb: 0.035~0.060%;Surplus is Fe and is inevitably mingled with;Controlled rolling, wherein slab heating temperature are used in hot rolling For 1200~1260 DEG C;Roughing outlet temperature is 1020~1080 DEG C;Hot rolling finishing temperature is 790~850 DEG C;In coiling process In, coiling temperature is 540~600 DEG C.The technical scheme enumerated is:C:0.075%;Si:0.02%;Mn:1.5%;P:0.02%;S: 0.01%;Als:0.03%;Nb:0.050%;1230 DEG C of slab heating temperature;820 DEG C of finishing temperature;570 DEG C of coiling temperature.This article The conventional laminar flow type of cooling to be used after hot rolled is offered, the alloy content that it has steel design is high, and cost is higher to ask Topic.
The content of the invention
The present invention is in view of the deficienciess of the prior art, provide a kind of in guarantee yield strength >=500MPa, tensile strength 550-700MPa, elongation percentage can reach that A >=17%, 180 ° of cross bending test D=1a is qualified, and yield tensile ratio reaches more than 0.85 Under the premise of, by using rear supper-fast sub-sectional cooling technique is rolled, under relatively low alloying component, improve the dent resistance of steel plate, plating 500MPa level automotive frame coated steels and production method that layer adhesive force is further enhanced.
Realize the measure of above-mentioned purpose:
A kind of 500MPa grades of automotive frame coated steel, its chemical composition and weight percent content are:C:0.06~ 0.09%, Si≤0.025%, Mn:1.10 ~ 1.29%, P≤0.015%, S≤0.006%, Als:0.020 ~ 0.060%, Nb:0.025~ 0.034%, surplus is Fe and inevitable impurity.
Preferably:Si weight percent content is no more than 0.018%.
Preferably:Nb weight percent content is 0.025 ~ 0.030%.
Produce a kind of method of 500MPa grades of automotive frame coated steel, its step:
1)Enter argon station Argon after converter smelting, and routinely add aluminum steel deoxidation and composition adjustment;Control argon blowing time:Bottom Blow and be not less than 4min, top blast is not less than 5min;
2)To heating strand after tapping and being casting continuously to form base, its heating and temperature control at 1280 ~ 1310 DEG C, 30 during heating ~ 40min;
3)Segmentation hot rolling is carried out, and controls roughing end temp at 1080 ~ 1110 DEG C, control finish rolling finishing temperature is 860 ~890℃;
4)Section cooling is carried out using the speed type of cooling is become, i.e.,:First cooled down in the case where cooling velocity is 140 ~ 160 DEG C/sec To 700 ~ 740 DEG C, the cooling velocity according still further to 5 ~ 10 DEG C/sec is cooled to coiling temperature;
5)Batched, control coiling temperature is at 550 ~ 580 DEG C;
6)Carry out finishing and rear process.
In the present invention the reasons why effect and control of each component and main technique:
Carbon:Carbon is cheap solution strengthening element.According to the application of this steel grade, it is mainly used in processing coating with greatly Beam, the parts such as transformer tower are sent, it is necessary to carry out a certain degree of Pressing Deformation processing, therefore it is required that material is meeting intensity requirement Meanwhile, with good cold formability energy.If its content is less than 0.06%, the requirement of the strength of materials can not be met;If its Content is more than 0.09%, then can not meet the favorable forming property of material.So, its content is limited to 0.06~0.09% model Enclose.
Silicon:Silicon is cheap and effective deoxygenation of liquid steel element, can also play a part of improving steel strength, but in this hair It is controlled by bright as harmful element.Should be more low better.Because silicon can deteriorate hot-rolled steel in the present invention The surface quality of plate, while making surface blackening in follow-up galvanizing process, influences it can zinc-plated property.Therefore carried out for silicone content Strict control, by its content is limited to less than 0.025%.Preferably:Si weight percent content is no more than 0.018%.
Manganese:Manganese is to improve intensity and the maximally effective element of toughness.If its content is less than 1. 10%, material can not be met Intensity requirement;But the manganese of addition volume, it can cause to increase the quenching degree of steel, make crackle quick due to welding the appearance of hardened layer Perception increases, and the cost of alloy of increase steel.In consideration of it, 1.29% will be defined to thereon, so, its content is limited to 1. 10~1.29% scopes.
Phosphorus:In order to avoid the welding performance of material, stamping formabilily, toughness, suitability for secondary processing deteriorate, setting Its upper content limit is 0.015%.So by the control of its content below 0.015%.
Sulphur:Sulphur is very harmful element.Sulphur in steel often exists with the oxide morphology of manganese, this sulphide inculsion pair The impact flexibility of steel is very unfavorable, and causes the anisotropy of performance, therefore, sulfur content in steel need to be controlled more low more It is good.Based on the consideration to Steel Sheet technique and manufacturing cost, plan sulfur content in steel and control below 0.008%.
Aluminium:Aluminium adds for deoxidation, when Als contents are less than 0.020%, it is impossible to play its effect;The opposing party Face, because the aluminium for adding volume easily forms aluminum oxide agglomerate, so, the regulation Als upper limits are 0.060%.Therefore, Als contents are limited It is scheduled on 0.020~0.060% scope.
Niobium:Niobium mainly improves the intensity of steel by crystal grain thinning and precipitation hardening, is strong carbon, nitrogen compound Formation element, it is main in steel to exist in Nb (C, N) form, growing up for austenite crystal is prevented, finally makes ferrite crystal grain chi It is very little to diminish, thinning microstructure.When its content is less than 0.025%, it is impossible to meet the requirement of material high intensity;And the niobium added is higher than When 0.034%, the requirement of its intensity and processability can be met, if adding again, cost of alloy can significantly rise.So, according to The performance objective requirement of steel grade, 0.025~0.034% scope is limited to by its content.Preferably:Nb weight percent content 0.025 ~ 0.030%.
For improve steel surface quality, it is ensured that material can zinc-plated property, present invention employs strand high temperature rapid firing technique It is one of critical process to carry out heating strand.The present invention takes 1280 ~ 1310 DEG C of heating-up temperatures to be to ensure the alloy in steel billet The minimum temperature that element is completely dissolved, while reducing the heating strand time, is controlled to be to reduce steel billet in 30 ~ 40min The stove internal oxidition time, reduce billet surface iron scale, improve surface quality.
On carrying out segmentation rolling, and roughing end temp is controlled at 1080 ~ 1110 DEG C, control finish rolling finishing temperature exists 865~890℃。
Why the present invention carries out section cooling using cooling speed change cooling, i.e., be according to cooling velocity at ultrafast cold section first 140 ~ 160 DEG C/sec carry out front ends it is cold by force, according still further to cooling velocity, 5 ~ 10 DEG C/sec are cooled to 550 ~ 580 DEG C of coiling temperature, be through After lot of experiments analysis, this type of cooling can make steel plate reach respective strengths requirement under relatively low design of alloy. Using sub-sectional cooling mode, the recrystal grain that not only can guarantee that in steel does not have started and cooled down in time when growing up, it is to avoid The generation of thick tissue, to obtain tiny metallographic structure, increases number of grain boundaries, improves the yield tensile ratio of material, and be conducive to To uniform metallographic structure, the precipitate even dispersion such as carbide is set to be distributed in base steel, it is ensured that material possesses good Cold formability energy.
The present invention compared with prior art, under relatively low design of alloy, using ultra-rapid cooling and sub-sectional cooling Technique, it has excellent surface quality and platability to the coating beam steel produced, can directly carry out galvanizing production, full The requirement of sufficient subsequent thermal galvanizer ordered pair plate surface quality, while steel plate has yield strength ReL >=460MPa, tensile strength 520-670MPa, elongation percentage can reach that A >=19%, 180 ° of cross bending test D=1a is qualified, and yield tensile ratio reaches more than 0.85 Under the premise of, the dent resistance of steel plate is improved, coating adhesion is further enhanced, with good surface quality.
Brief description of the drawings
Accompanying drawing is metallographic structure figure of the present invention.
Embodiment
The present invention is described in detail below:
Table 1 is the comparative example of various embodiments of the present invention;
Table 2 is the main technologic parameters list of various embodiments of the present invention;
Table 3 is various embodiments of the present invention performance text list.
Various embodiments of the present invention are produced according to following steps:
1)Enter argon station Argon after converter smelting, and routinely add aluminum steel deoxidation and composition adjustment;Control argon blowing time:Bottom Blow and be not less than 4min, top blast is not less than 5min;
2)To heating strand after tapping and being casting continuously to form base, its heating and temperature control at 1280 ~ 1310 DEG C, 30 during heating ~ 40min;
3)Segmentation hot rolling is carried out, and controls roughing end temp at 1080 ~ 1110 DEG C, control finish rolling finishing temperature is 860 ~890℃;
4)Section cooling is carried out using the speed type of cooling is become, i.e.,:First cooled down in the case where cooling velocity is 140 ~ 160 DEG C/sec To 700 ~ 740 DEG C, the cooling velocity according still further to 5 ~ 10 DEG C/sec is cooled to coiling temperature;
5)Batched, control coiling temperature is at 550 ~ 580 DEG C;
6)Carry out finishing and rear process.
The composition value list of the various embodiments of the present invention of table 1 and comparative example(wt%)
The main technologic parameters list of the various embodiments of the present invention of table 2 and comparative example
The various embodiments of the present invention of table 3 and comparative example mechanical properties test the results list
It can be analyzed from table 3, the present invention is under using ultra-rapid cooling and sub-sectional cooling technique, with less than comparative example Design of alloy, obtains the mechanical property higher than comparative example, and production cost is substantially reduced, while the cold forming of product Performance is improved, and is 2 times of comparative example.
Present embodiment is only most preferably to enumerate, not to the restricted implementation of technical solution of the present invention.

Claims (1)

1. a kind of ultrafast cold production method of 500MPa grades of automotive frame coated steel, its step:
1)Enter argon station Argon after converter smelting, and routinely add aluminum steel deoxidation and composition adjustment;Control argon blowing time:Bottom blowing is not Less than 4min, top blast is not less than 5min;
2)To heating strand after tapping and being casting continuously to form base, its heating and temperature control at 1280 ~ 1310 DEG C, the heat time 30 ~ 40min;Chemical Composition in Cast Billet and weight percent content are:C:0.06 ~ 0.09%, Si≤0.025%, Mn:1.10 ~ 1.29%, P ≤ 0.015%, S≤0.006%, Als:0.020 ~ 0.060%, Nb:0.025 ~ 0.034%, surplus is Fe and inevitable impurity;
3)Segmentation hot rolling is carried out, and controls roughing end temp at 1080 ~ 1110 DEG C, control finish rolling finishing temperature is 860 ~ 877 ℃;
4)Section cooling is carried out using the speed type of cooling is become, i.e.,:First it is cooled in the case where cooling velocity is 153 ~ 160 DEG C/sec 705 ~ 740 DEG C, the cooling velocity according still further to 5 ~ 7 DEG C/sec is cooled to coiling temperature;
5)Batched, control coiling temperature is at 550 ~ 580 DEG C;
6)Carry out finishing and rear process.
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CN105401071B (en) * 2015-12-22 2017-12-29 武汉钢铁有限公司 A kind of 500MPa levels car Galvanized Dual Phase Steel and production method
CN105441805B (en) * 2015-12-22 2018-06-26 武汉钢铁有限公司 A kind of 800MPa grades of car Galvanized Dual Phase Steel and production method
CN105369135B (en) * 2015-12-22 2017-11-17 武汉钢铁有限公司 A kind of 450MPa levels car Galvanized Dual Phase Steel and production method
CN107675087A (en) * 2017-11-17 2018-02-09 武汉钢铁有限公司 A kind of good mine wheel-use steel material of low temperature impact properties and production method
CN107675088B (en) * 2017-11-17 2019-10-01 武汉钢铁有限公司 Tensile strength is >=590MPa think gauge wheel rim steel and production method
CN107904501A (en) * 2017-11-20 2018-04-13 武汉钢铁有限公司 A kind of good high intensity Thin Specs wheel of anti-fatigue performance is used and production method

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JP3528716B2 (en) * 1999-11-05 2004-05-24 Jfeスチール株式会社 High-strength cold-rolled steel sheet, high-strength galvanized steel sheet excellent in surface properties and press formability, and manufacturing method thereof
CN102776442B (en) * 2012-07-27 2014-04-09 武汉钢铁(集团)公司 Hot rolled steel used for stirrer in automotive stirring tank and production method thereof
CN103966504B (en) * 2013-01-24 2016-12-28 宝山钢铁股份有限公司 A kind of 500MPa level low yield strength ratio straight weld steel pipe and manufacture method thereof
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