CN104641008B - Flat cold-rolled bar product and manufacture method thereof - Google Patents
Flat cold-rolled bar product and manufacture method thereof Download PDFInfo
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- CN104641008B CN104641008B CN201380048837.7A CN201380048837A CN104641008B CN 104641008 B CN104641008 B CN 104641008B CN 201380048837 A CN201380048837 A CN 201380048837A CN 104641008 B CN104641008 B CN 104641008B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 37
- 239000010959 steel Substances 0.000 claims abstract description 37
- 238000000137 annealing Methods 0.000 claims abstract description 33
- 239000010949 copper Substances 0.000 claims abstract description 28
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000011651 chromium Substances 0.000 claims abstract description 21
- 229910052802 copper Inorganic materials 0.000 claims abstract description 21
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 20
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000005098 hot rolling Methods 0.000 claims abstract description 20
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 20
- 239000011572 manganese Substances 0.000 claims abstract description 19
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- 238000005097 cold rolling Methods 0.000 claims abstract description 17
- 230000000717 retained Effects 0.000 claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 13
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 13
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 12
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 12
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000010936 titanium Substances 0.000 claims abstract description 8
- 239000010955 niobium Substances 0.000 claims abstract description 7
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 6
- 239000010703 silicon Substances 0.000 claims abstract description 6
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 229910052803 cobalt Inorganic materials 0.000 claims abstract description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 4
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims abstract description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract 3
- 239000010941 cobalt Substances 0.000 claims abstract 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract 3
- 239000011733 molybdenum Substances 0.000 claims abstract 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium(0) Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims abstract 3
- 230000000875 corresponding Effects 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 235000019580 granularity Nutrition 0.000 claims description 3
- 239000010409 thin film Substances 0.000 claims description 2
- 229920001296 polysiloxane Polymers 0.000 claims 1
- 230000015572 biosynthetic process Effects 0.000 abstract description 7
- 238000005755 formation reaction Methods 0.000 abstract description 7
- 239000000047 product Substances 0.000 description 33
- 230000000694 effects Effects 0.000 description 9
- 238000005096 rolling process Methods 0.000 description 8
- 101700000038 mpas Proteins 0.000 description 7
- 239000000203 mixture Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 230000001131 transforming Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 229910000529 magnetic ferrite Inorganic materials 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000010960 cold rolled steel Substances 0.000 description 2
- 230000002349 favourable Effects 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching Effects 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000161 steel melt Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 230000003064 anti-oxidating Effects 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000003111 delayed Effects 0.000 description 1
- 238000006392 deoxygenation reaction Methods 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 238000003618 dip coating Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 239000006193 liquid solution Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- TWXTWZIUMCFMSG-UHFFFAOYSA-N nitride(3-) Chemical compound [N-3] TWXTWZIUMCFMSG-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910001568 polygonal ferrite Inorganic materials 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
The present invention relates to the flat cold-rolled bar product that a kind of Rm is more than 1400MPa and A80 is more than 5% and also the method relating to producing this kind of flat product.Flat product according to the present invention also includes the carbon in terms of weight % in addition to ferrum and inevitable impurity: 0.10 0.60%, silicon: 0.4 2.5%, aluminum: up to 3.0%, manganese: 0.4 3.0%, nickel: up to 1.0%, copper: up to 2.0%, molybdenum: up to 0.4%, chromium: up to 2%, cobalt: up to 1.5%, titanium: up to 0.2%, niobium: up to 0.2%, vanadium: up to 0.5%.Its microstructure includes the bainite of 20 more than volume %, the retained austenite of 10 35 volume % and the martensite as remainder.Manufacture for this flat product, it is by the slab with described component, thin plate or casted steel belt manufacture, these primary product are had the hot rolled strip of at least 830 DEG C of hot rolling end temps by hot rolling with formation, this hot rolled strip is wound under the coiling temperature below 560 DEG C, this hot-strip is had the cold-rolled strip of more than 30% cold rolling degree and this cold-rolled strip is heat-treated by being first heated to annealing temperature more than 800 DEG C by cold rolling to be formed, it is cooled to the holding temperature more than martensite start temperature MS with the cooldown rate of at least 8 DEG C/s subsequently and is then retained in this holding temperature until at least 20 volume % bainites occur in the microstructure of cold-rolled strip.
Description
Technical field
The present invention relates to ductility A80 cold rolling of a kind of tensile strength Rm with at least 1400 MPas and at least 5%
Flat product.Such product is due to the highest intensity and has good ductility and well-known, and is especially suitable for
For manufacturing the parts of body of motor vehicle.
Present invention is equally related to a kind of method for manufacturing the flat product according to the present invention.
Background technology
Steel plate that term " flat product " is herein understood to mean to be manufactured by rolling mill practice or steel band and sheet band and
The analog separated from which.
Wherein, alloy content is only stated with " % " at this, and this always means that " percentage by weight ", unless additionally quilt
Clearly state.
EP1466024B1 (DE60315129T2) discloses a kind of method producing flat product, and it is intended to production has
It is significantly higher than the tensile strength of 1000 MPas.In order to reach this purpose, the molten steel of fusing is manufactured, and wherein contains with weight
The carbon of the 0.0005-1% of percentage ratio, the copper of 0.5-10%, the manganese of up to 2%, the silicon of up to 5%, the titanium of up to 0.5% is high
Reach 0.5% niobium, the nickel of up to 5%, the aluminum of up to 2% and as the ferrum of remainder and owing to producing reason and inevitable
Impurity.This molten steel melt is cast to form banding, most 10 millimeters and sprayed by water or water-air mixture of its thickness
It is quickly cooled at a temperature of at most 1000 DEG C.Then, this cast steel strip carries out hot rolling under conventional warm-down rate.Hot rolling is terminating
At a temperature of complete, the most all of copper is still within solid solution in ferrite and/or austenite matrix.Then,
This band stands quick refrigerating work procedure, thus is maintained at by copper in the supersaturated solid solution of ferrite and/or austenite solution.?
After being cooled into steel ring, cold steel band can be formed by the rolling of hot steel band and thus obtain the cold rolling degree reaching 40-80%.This is cold
Strip rolling carries out recrystallization annealing subsequently, and it is brought into the annealing temperature being in 840 DEG C of regions also as quickly as possible during this period
And keep at said temperatures, in order to Copper in Iron and Steel is added in solution by maximum possible ratio.It is fast quickly cooling after this
But arrive 400-700 DEG C of temperature, the most again form the precipitate of Cu.By this way, the purpose of precipitation-hardening is
Realize the ideal tensile strength of steel.Meanwhile, the content of copper is to increase the corrosion-resistant of iron and steel by formation antioxidation nitride layer
Property and anti-fragility.
The other method of the cold-rolled strip producing very high strength is disclosed by US7591977B2.According to the method, containing (with
Percentage by weight meter) carbon of 0.1-0.25%, the hot rolled strip of the silicon of 1.0-2.0% and the manganese of 1.5-3.0% is cold with 30-70%
The degree rolled is to form cold-rolled strip, and then this cold steel band completes heat treatment in continuous print path.In this heat treatment, this is cold
Strip rolling is heated to the first annealing temperature on Ar3 temperature in the first annealing steps, in order to be present in described cold-rolled steel
Carbide in band is brought in solution.It is followed by cooling, starts from the first annealing temperature and with the cooling of at least 10 DEG C/sec
Speed is to the second annealing temperature.This temperature is selected such that bainite form and is usually located at 300-450 in cold-rolled strip
In the range of DEG C.Implement to be performed with this second annealing steps forming bainite until the microstructure of this cold-rolled strip is by extremely
The bainite of few 60% degree and the retained austenite of at least 5% degree and remaining polygonal ferrite form.Here,
It is an object of the invention to the composition that the microstructure of maximum possible scope is bainite and other microstructure at most exist
Vestige.Thus the cold-rolled strip provided realizes the tensile strength of up to 1180 MPas and possesses the ductility of at least 9%, and
If it is desired, it is possible to use the metal level of anticorrosive protection to be coated.
Summary of the invention
For the background technology of above-mentioned described prior art, it is an object of the invention to provide a kind of flat cold-rolled bar and produce
Product, it can carry out producing and have the intensity of raising further and good deformable with simple and operation reliable way
The optimum organization characteristic of property.Further it is an object to a kind of method producing such flat cold-rolled bar product.
For flat cold-rolled bar product, achieved by the flat product shown in claim 1 according to this purpose of the present invention.
As for the method, it is achieved according to the purpose that the present invention is mentioned above, the most at least shown in claim 12
Job step be implemented to produce according to the flat cold-rolled bar product of the present invention.
The favourable configuration of the present invention illustrates in the dependent claims and upperseat concept as the present invention will
It is explained in detail below.
Flat cold-rolled bar product according to the present invention differs from addition to ferrum and inevitable impurity, and it includes
(percentage by weight):
C:0.10-0.60%,
Si:0.4-2.5%,
Al: up to 3.0%,
Mn:0.4-3.0%,
Ni: up to 1.0%,
Cu: up to 2.0%,
Mo: up to 0.4%,
Cr: up to 2%,
Co: up to 1.5%,
Ti: up to 0.2%,
Nb: up to 0.2%,
V: up to 0.5%.
Here, under Cold Rolled Strip, according to the microstructure of the flat product of the present invention by the bayesian of at least 20 volume %
Body, 10-35 volume % retained austenite and as the martensite of remainder, self-evidently the most inevitable
The vestige of composition of other microstructure may be present in the microstructure of this flat product.According to the present invention, with this kind of side
The flat cold-rolled bar product that formula is provided reaches tensile strength Rm of at least 1400 MPas and ductility A80 of at least 5%.Retained austenite
C content in family name's body is generally higher than the 1.0% of weight.
According to provided by the present invention or according to the present invention contemplated include following work for the method producing flat product
Make step:
-in the way of slab, sheet billet or casted steel belt, providing primary product, it is in addition to ferrum and inevitable impurity
Including (with percentage by weight) C:0.10-0.60%, Si:0.4-2.5%, Al: up to 3.0%, Mn:0.4-3.0%, Ni: high
Reach 1.0%, Cu: up to 2.0%, Mo: up to 0.4%, Cr: up to 2%, Co: up to 1.5%, Ti: up to 0.2%, Nb: high
Reach 0.2%, V: up to 0.5%；
Primary product described in-hot rolling are to form hot rolled strip, wherein, obtained heat in one or more roll path
Strip rolling has the hot rolling end temp of at least 830 DEG C when it leaves last roll path；
Obtained hot-strip is wound under-coiling temperature between hot rolling end temp and 560 DEG C；
-this hot rolled strip cold rolling has at least 30% cold rolling cold-rolled strip to be formed；
Cold-rolled strip obtained by-heat treatment, wherein during described heat treatment, this cold-rolled strip
-heated the annealing temperature reaching at least 800 DEG C,
-optionally under this annealing temperature keep the 50-150 second anneal duration,
-be cooled to keep temperature from this annealing temperature with the cooldown rate of at least 8 DEG C/s, this holding temperature is positioned at holding
In temperature range, this holding temperature range has 470 DEG C of upper limits and has the lower limit higher than martensite start temperature MS, from this
Martensite start temperature starts, martensite form in the microstructure of cold-rolled strip, and
-be kept at a temperature of this holding and be enough in the microstructure of cold-rolled strip, form at least 20 volume % bainites
A period of time.
Steel band according to the present invention has three-phase microstructure, the most prevailing composition be martensite and its also
Austenite by the bainite remained with as remainder forms.It is preferred here that the ratio of bainite is at least 50 bodies
Amass %, particular at least 60 volume %, and the ratio of this retained austenite is in 10-25 volume %, and every kind of situation
Under the remainder of microstructure that is made up of martensite.Preferably the ratio of martensite is at least 10 volume %.There is this kind
The microstructure of component produces the best of breed of the Rm*A80 with required tensile strength.
Except main component " bainite ", " retained austenite " and " martensite ", the component of other microstructure occurs
Content is possible, but the ratio of these components is the lowest to such an extent as to the performance of the cold-rolled strip according to the present invention is not had shadow
Ring.This retained austenite is mainly to have the shape of the thin film on the globular island of the block retained austenite less than 5 micron granularities
Formula is present in according in the cold-rolled strip of the present invention so that described retained austenite has high stability also in an initial condition
And associated therewith be the low trend being changed into undesirable martensite.When the higher degree of deformation, martensite is by this
Retained austenite (TRIP effect) is formed, and which increases the ductility of fracture.
Cold-rolled strip produced according to the invention is typically implemented tensile strength Rm more than 1400 MPas, has similar normal
Ductility A80 more than 5% of rule.Therefore, it is usually more than according to quality Rm*A80 of the flat product of the present invention
7000MPa*%, typically achieves quality Rm*A80 with at least 13500MPa*%.This cold-rolled steel according to the present invention
Band is to have the highest intensity and the optimum organization of enough deformabilities.
The beginning temperature of martensite, i.e. starts martensite form in the steel processed according to the present invention from this temperature, permissible
The 178-180 of the metal science 15 (Metal Science 15) published it is published in 1981 based on author H.Bhadeshia
Page, entitled " Thermodynamic Extrapolation and Martensite-Start-Temperature of
Substitutionally Alloyed Steels " article described in operation calculate.
According in the steel of the present invention, carbon is delayed the transformation to ferrite/pearlite (pearlite), reduces geneva
Beginning temperature MS of body and contribute to increasing hardness.In order to utilize these positive effects, according to the flat product of the present invention
C content can be configured so that at least 0.25 weight %, particular at least 0.27 weight % or at least 0.28 weight %, by relatively
It is possible that the high effect acquired by carbon content is particularly securely used, when C content is in less than 0.25-0.5 weight
In the range of amount %, particularly 0.27-0.4 weight % or 0.28-0.4 weight %.
Copper increases the effect of intensity and can also be used in the flat cold-rolled bar product according to the present invention.In this respect, minimum
The Cu content of 0.15 weight % particular at least 0.2 weight % may alternatively appear in according in the flat product of the present invention.Copper is for by force
Degree contribute to particularly effective effect, if it is present in the flat product according to the present invention with the content of at least 0.55 weight %
In；Based on the fact that it is possible for the content of Cu being limited in most 1.5 weight % and suppresses Cu to there is produced counter productive.
According in the steel of the present invention, at least 0.4 weight % and at most 3 weight %, the most up to 2.5 weight % contain
The Mn of amount, promotes the formation of bainite, and the copper optionally in addition existed, the content of chromium and nickel similarly helps to the shape of bainite
Become.Depend on other composition corresponding of the steel processed according to the present invention, Mn content can also be limited valuably at this
Below many 2 weight % or increase Mn minimum content to 1.5 weight %.
Optionally adding of Cr can also reduce the beginning temperature of martensite and suppress bainite transformation to become pearly-lustre
Body or the trend of cementite.Additionally, as predefined, when Cr content is limited to 1.5 weight % according to present invention institute
The optional effect with the existence of the Cr in the flat cold-rolled bar product according to the present invention can raise, for up at most 2 weights
When measuring the content of the % upper limit, chromium promotes ferritic transformation.The actively impact of Cr can be particularly effectively used, if
The Cr of at least 0.3 weight % is present in according in the flat product of the present invention.
The interpolation of Ti, V or Nb is optional equally, and it can be supported the formation of fine granularity microstructure and promote bayesian
The transformation of body.Additionally, the increase helping to hardness that these microalloy elements are by precipitate.The positive effect of Ti, V and Nb
Fruit can be used in the flat cold-rolled bar product according to the present invention, at the content of these elements in a particularly efficient manner
In the range of 0.002-0.15 weight %, especially no more than 0.1 weight %.
Silicon is present in according in the flat product of the present invention and cause sizable solid with the content of 0.4-2.5 weight %
Liquid solution solidifies.In order to utilize this effect in a particularly reliable manner, the content of Si can be configured so that at least 1.0 weights
Amount %.Similarly, in order to avoid negative effect, limit Si content be most 2 weight % be useful.
In the steel processed according to the present invention, aluminum can partly substitute the content of Si.Meanwhile, similar with Si, aluminum exists
Steel manufacture process has deoxygenation.For this purpose, it is provided that the Al of minimum 0.01 weight % content.Higher
Aluminum content be proved to be favourable, be such as in order to the hardness of iron and steel or tensile strength are set as low value when the interpolation of Al
It is beneficial to the morphotropism improved.
Another function of Si and Al includes the formation suppressing carbide in bainite and therefore stablizes by dissolving C
Retained austenite is until low temperature.
Therefore the positive impact existed while Al and Si can be utilized, when the content of Si and Al is in
According in the range of the predefined restriction of the present invention to meet following condition: 0.8%Si+0.8%Al ＞ 1.2 weight % (its
In, %Si characterizes the content of the Si in terms of weight %, and Al% characterizes the content of the Al in terms of weight %).
The formation of the predefined microstructure according to the present invention can be ensured that, particularly by this fact i.e. according to this
The content of manganese, chromium, nickel, copper and carbon in the iron and steel processed of invention and according to manganese corresponding in the band steel of the present invention, chromium,
The content of nickel, copper and carbon meets following condition:
1 ＜ 0.5%Mn+0.167%Cr+0.125%Ni+0.125% copper+1.334%C ＜ 2
Wherein, %Mn characterizes the content of the corresponding Mn in terms of weight %, and %Cr characterizes containing of the corresponding Cr in terms of weight %
Amount, %Ni characterizes the content of the corresponding Ni in terms of weight %, and %Cu characterizes content and the %C sign of the corresponding Cu in terms of weight %
The content of the corresponding C in terms of weight %.
In order to produce the flat product according to the present invention, by have the constituent according to the present invention steel cast original or
First person's primary product are brought to or are maintained at certain temperature, and this temperature be enough to terminate hot rolling technology, and this hot rolling technology is from being positioned at
This temperature at hot rolling end temp in the range of 830-1000 DEG C starts to perform processing.Leave at it and be used for the last of hot rolling
After rolling support, described hot rolled strip is cooled in the roller tables adjacent with roll mill.And then this roller tables, this hot-rolled steel is brought into
Enter in coiler device, be wound wherein to form a volume circle.
Coiling temperature must be at least 560 DEG C so that hot rolled strip microcosmic softer, that be made up of ferrite and pearlite
Structure is formed.Preferable temperature curve for this purpose creates, if hot rolling end temp is in the scope of 850-950 DEG C
In, particularly in the range of 880-950 DEG C.For this purpose it is proposed, generally primary product are heated to be positioned at the model of 1100-1300 DEG C
At a temperature of being somebody's turn to do before enclosing at a temperature of interior or being maintained at hot rolling.The microstructure of so obtained hot rolled strip is mainly by ferrum element
Body and pearlite composition.Occur that the risk of grain boundary oxidation can be minimized by this fact, i.e. this coiling temperature is restricted to
The highest 750 DEG C.
After winding, this hot rolled strip is carried out cold rolling, self-evidently, hot rolled strip can before cold rolling by chemistry or
Machinery means are removed oxide layer routinely.
Cold rolling it is implemented at least 30% particular at least 45% cold rolling degree, in order to add in annealing process subsequently
Speed recrystallization and transformation.The most preferably surface quality can also obtain by observing cold rolling relatively high degree.At least
The cold rolling degree of 50% has been demonstrated it is particularly advantageous for the purpose.
After cold rolling, complete the annealing cycle in continuous path according to the cold-rolled strip obtained by the present invention, during this period,
It is heated at least 800 DEG C at the first annealing stage, the temperature of preferably at least 830 DEG C.This first annealing stage is the most at least
So a period of time, thus this cold-rolled strip is by complete austenitizing.The 50-150 second is typically required for this.
Annealing stage phase first, this product is at least 8 DEG C/sec particularly 10 DEG C/sec with rate of cooling and is quenched.For this
The target temperature of quenching is the holding temperature of most 470 DEG C and it is higher than martensite start temperature MS, starts temperature from this,
Martensite form cold-rolled strip microstructure in.In practice, the scope of 300-420 DEG C particularly 330-420 DEG C is permissible
It is used to indicate that this scope residing for holding temperature.
Starting processing from respective holding temperature, cold-rolled strip is maintained at holding temperature range at the second annealing stage
In, precisely until the microstructure of the cold-rolled strip of at least 20 volume % has been converted into bainite.This is maintained at this can
Keep or slow within keeping temperature range being performed during cooling isothermal at a temperature of the holding arrived such as
Reduce temperature.
Flat product produced according to the invention can the most metal coated protective layer.Such as this can pass through
Hot dip coating realizes.If needing annealing before metal coating applies, can be according to heat treatment provided by the present invention
Carry out during this annealing.
Detailed description of the invention
The present invention will be described in more details on the basis of exemplary embodiment subsequently.
Five pieces of steel S1-S5 are melted, and its component is labeled in Table 1.
The steel melt of respective components is carried out pouring to form blank in a conventional manner, isolates thickness from this blank
Plate.Then the plate of this thickness is heated to reheat temperature with similar usual manner.
Heated slab is had the hot rolled strip of 2mm thickness with similar conventional hot rolling station group by hot rolling with formation.
In each case, this hot rolling end temp is in the range of 830-900 DEG C.This hot rolled strip is by from this temperature
It is cooled to be positioned at the coiling temperature on 560 DEG C and be wound subsequently to form volume circle.
This hot rolled strip so obtained is removed top layer and removing after top layer by cold rolling with shape after winding
Become there is the cold-rolled strip of 50% cold rolling degree.
The relatively great amount of sample of these cold-rolled strips is then subjected to heat treatment, and in this heat treatment, it is in the first annealing
Step is heated to the first annealing temperature being positioned in the range of 830-850 DEG C with the rate of heat addition of at least 1.9 DEG C/sec.This is cold
Strip rolling is kept the time of 120 seconds in this temperature, until they are the most completely heated up.
Being followed by quenching, during this period, cold-rolled strip is quenched into the cooldown rate of at least 8 DEG C/sec and is in
Holding temperature T2 in the range of 350-420 DEG C.Specifically, in first of test, this holding temperature T2 is 300 DEG C, 310
DEG C, 330 DEG C, 340 DEG C, 375 DEG C, 390 DEG C and 410 DEG C.The sample of this cold-rolled strip is kept at respective holding temperature T2
Anneal duration t2.
In FIG, hot strength Rm that realized is drawn for the figure of respective annealing temperature T2.It can be seen that by
The cold-rolled strip sample that steel S5 produces only all reaches 1400 MPas of required minimum tensile strength under specific annealing conditions,
But the hot strength of the cold-rolled strip sample produced by other steel is the most reliably higher than minimum limit 1400 MPas.Steel S5 phase
Low carbon content is in the lower limit of the content range set in advance according to the present invention, has been confirmed as the very crux.
In fig. 2, steel S4 during the annealing of drawn second annealing stage of hot strength of the cold-rolled strip sample produced
Between the figure of t2.No matter it can be seen that respective annealing time t2, i.e. existing at a temperature of the holding of 310 DEG C, 330 DEG C and 350 DEG C
The cold-rolled strip sample being kept at a temperature of holding in the holding temperature range of 310-350 DEG C has reached required
1400MPa hot strength.
In figure 3, steel S5 the hot strength of the cold-rolled strip sample produced is similarly plotted as the second annealing
The diagram of the anneal duration t2 in stage.It will be seen that i.e. at 350-390 DEG C of model at a temperature of the holding of 350 DEG C and 390 DEG C
The cold-rolled strip sample being kept at a temperature of enclosing interior holding reaches required 1400MPa hot strength, if annealing continues
Time t2 is less than 145 seconds.
In the diagram, steel S4 ductility A80 of the cold-rolled strip sample produced is plotted as the second annealing stage
The diagram of anneal duration t2.No matter corresponding anneal duration t2, in the holding temperature of 310 DEG C, 330 DEG C and 350 DEG C
Under i.e. keep under temperature range at 310-350 DEG C, the cold-rolled strip sample being kept reaches required minimum ductility A80.
In Figure 5, steel S5 ductility A80 of the cold-rolled strip sample produced is plotted as the second annealing stage
The diagram of annealing time t2.At this it can also be seen that no matter each keeps temperature T2 and each anneal duration t2 thereof, this is cold
Strip rolling sample has reached required ductility A80 of at least 5%.Therefore, if short anneal duration and the lowest guarantor
Hold temperature T 2 to be complied with performing, there is high tensile strength Rm and be combined with cold according to the present invention of enough ductility A80
Draw down product made from steel can be produced by steel S5, although its relatively low C content.
Fig. 6 shows the enlarged drawing of the cross section of the cold-rolled strip according to the present invention in part.In the figure, such as
The block RA-b of retained austenite is labeled and this is emphasized by the mode drawn a circle, at this point, and film like retained austenite
Body RA-f presents with the layered mode of stratiform.
Claims (15)
1. a flat cold-rolled bar product, has tensile strength Rm of at least 1400MPa and ductility A80 of at least 5%, and removes
Outside ferrum and inevitable impurity, containing in terms of weight %:
Carbon: 0.10-0.60%,
Silicon: 0.4-2.5%,
Aluminum: up to 3.0%,
Manganese: 0.4-3.0%,
Nickel: up to 1.0%,
Copper: up to 2.0%,
Molybdenum: up to 0.4%,
Chromium: up to 2%,
Cobalt: up to 1.5%,
Titanium: up to 0.2%,
Niobium: up to 0.2%,
Vanadium: up to 0.5%,
Wherein, the microstructure of this flat product is by reaching the bainite of at least 20 volume %, reaching the residual of 10 35 volume %
Austenite and the martensite as remainder form, and described retained austenite is mainly to have less than 5 micron granularities
Presented in the thin film on the globular island of block retained austenite in described flat cold-rolled bar product.
Flat product the most according to claim 1, it is characterised in that the carbon content of this flat product is at least 0.25 weight
Amount %.
3. according to the flat product described in aforementioned any one claim, it is characterised in that the carbon content of this flat product is
At least 0.27 weight %.
4. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the silicone content of this flat product
It is at least 1.0 weight %.
5. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the aluminum content of this flat product
It is at least 0.01 weight %.
6. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the copper content of this flat product
It is at least 0.2 weight %.
Flat product the most according to claim 5, it is characterised in that the copper content of this flat product is at least 0.55 weight
Amount %.
8. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that: the chromium content of this flat product
It is at least 0.3 weight %.
9. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the manganese of this flat product, chromium,
The content of nickel, copper and carbon meets following condition:
1 < 0.5% manganese+0.167% chromium+0.125% nickel+0.125% copper+1.334% carbon < 2,
Wherein, % manganese: the content of the corresponding manganese in terms of weight %,
% chromium: the content of the corresponding chromium in terms of weight %,
% nickel: the content of the corresponding nickel in terms of weight %,
% copper: the content of the corresponding copper in terms of weight %,
% carbon: the content of the corresponding carbon in terms of weight %.
10. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the microcosmic of this flat product
Structure includes the bainite of at least 50 volume %.
11. according to the flat product according to any one of aforementioned claim 1-2, it is characterised in that the microcosmic of this flat product
Structure includes the retained austenite of 10-25 volume %.
The method of 12. 1 kinds of flat products constituted according to claim 1 to 11 any one for manufacture, described method includes
Following job step:
Thering is provided primary product with slab, thin plate or casted steel belt mode, it includes with weight in addition to ferrum and inevitable impurity
The carbon of amount % meter: 0.10-0.60%, silicon: 0.4-2.5%, aluminum: up to 3.0%, manganese: 0.4-3.0%, nickel: up to 1.0%,
Copper: up to 2.0%, molybdenum: up to 0.4%, chromium: up to 2%, cobalt: up to 1.5%, titanium: up to 0.2%, niobium: up to 0.2%,
Vanadium: up to 0.5%；
Primary product described in hot rolling are to form hot rolled strip, wherein, obtained hot-rolled steel in one or more roll path
Band has the hot rolling end temp of at least 830 DEG C when it leaves last roll path；
Obtained hot-strip is wound under the coiling temperature between these hot rolling end temp and 560 DEG C；
This hot rolled strip cold rolling has the cold-rolled strip of at least 30% cold rolling degree to be formed；
Cold-rolled strip obtained by heat treatment, wherein, during described heat treatment, this cold-rolled strip
-it is heated to reach the annealing temperature of at least 800 DEG C,
-be cooled to keep temperature from this annealing temperature with the cooldown rate of at least 8 DEG C/s, this holding temperature is positioned at holding temperature
In the range of, this holding temperature range has 470 DEG C of upper limits and has the lower limit higher than martensite start temperature MS, from this geneva
Body starts temperature and starts, and martensite is formed in the microstructure of this cold-rolled strip, and
-be kept at a temperature of this holding and be enough in the microstructure of cold-rolled strip, form the one of at least 20 volume % bainites
The section time.
13. described methods according to claim 12, it is characterised in that this hot rolling end temp is 850-950 DEG C.
14. according to the described method of one of claim 12 and 13, it is characterised in that this holding temperature is 300-420 DEG C.
15. according to the described method of claim 12 to 13 any one, it is characterised in that this cold-rolled strip after heat treatment by
It is coated with coat of metal.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP12178332.8A EP2690184B1 (en) | 2012-07-27 | 2012-07-27 | Produit plat en acier laminé à froid et son procédé de fabrication |
| EP12178332.8 | 2012-07-27 | ||
| PCT/EP2013/065838 WO2014016421A1 (en) | 2012-07-27 | 2013-07-26 | Cold-rolled flat steel product and method for the production thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104641008A CN104641008A (en) | 2015-05-20 |
| CN104641008B true CN104641008B (en) | 2016-11-30 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1729307A (en) * | 2002-12-20 | 2006-02-01 | 于西纳股份有限公司 | A steel composition for the production of cold rolled multiphase steel products |
| CN102149841A (en) * | 2008-09-10 | 2011-08-10 | 杰富意钢铁株式会社 | High-strength steel sheet and method for production thereof |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1729307A (en) * | 2002-12-20 | 2006-02-01 | 于西纳股份有限公司 | A steel composition for the production of cold rolled multiphase steel products |
| CN102149841A (en) * | 2008-09-10 | 2011-08-10 | 杰富意钢铁株式会社 | High-strength steel sheet and method for production thereof |
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