WO2012133540A1 - 熱延鋼板及びその製造方法 - Google Patents
熱延鋼板及びその製造方法 Download PDFInfo
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- WO2012133540A1 WO2012133540A1 PCT/JP2012/058160 JP2012058160W WO2012133540A1 WO 2012133540 A1 WO2012133540 A1 WO 2012133540A1 JP 2012058160 W JP2012058160 W JP 2012058160W WO 2012133540 A1 WO2012133540 A1 WO 2012133540A1
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
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- C21D2211/00—Microstructure comprising significant phases
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Definitions
- the present invention relates to a hot-rolled steel sheet excellent in local deformability such as bendability, stretch flangeability, burring workability, hole expandability, and the like, having less orientation dependency of formability and excellent in ductility, and a method for producing the same.
- the present invention relates to a steel sheet using a TRIP (Transformation Induced Plasticity) phenomenon.
- TRIP Transformation Induced Plasticity
- Non-Patent Document 1 discloses a method for ensuring uniform elongation by allowing austenite to remain in a steel sheet.
- Non-Patent Document 1 also discloses a method for controlling the metal structure of a steel sheet that improves the local ductility required for bending, hole expanding, and burring.
- Non-Patent Document 2 discloses that if inclusions are controlled, the microstructure is controlled to a single structure, and the hardness difference between the microstructures is reduced, it is effective for bendability and hole expansion processing. ing.
- Non-Patent Document 3 the technology for obtaining an appropriate fraction of ferrite and bainite by controlling the metal structure by cooling control after hot rolling and controlling precipitates and transformation structure is also disclosed in Non-Patent Document 3. Is disclosed. However, since either method is a method for improving the local deformability depending on the structure control (control of the microstructure on the classification), the local deformability is greatly influenced by the base structure.
- Non-Patent Document 4 discloses a technique for improving the material of a hot-rolled steel sheet by increasing the amount of reduction in the continuous hot rolling process. Such a technique is a so-called crystal grain refining technique.
- the main phase of a product is obtained by transforming unrecrystallized austenite into ferrite by performing large pressure at the lowest possible temperature in the austenite region. A certain ferrite crystal grain is refined to enhance strength and toughness.
- no consideration is given to improvement of local deformability and ductility.
- the structure control mainly including inclusions has been performed.
- TRIP steel is excellent in strength and ductility, it is generally characterized by low local deformability such as hole expansibility. Therefore, in order to use this TRIP steel, for example, as a high-strength steel plate for undercarriage parts, local deformability such as hole expansibility must be improved.
- the present inventors have found that, in TRIP steel, local deformability is improved when the pole density of a predetermined crystal orientation is appropriately controlled.
- the present inventors succeeded in producing a steel sheet excellent in local deformability and other mechanical properties by optimizing the chemical composition and production conditions of TRIP steel and controlling the microstructure of the steel sheet.
- the gist of the present invention is as follows.
- the chemical composition of the steel sheet is, by mass, C: 0.02% or more and 0.5% or less, Si: 0.001% or more, and 4.0. %: Mn: 0.001% or more and 4.0% or less, Al: 0.001% or more and 4.0% or less, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, O: 0.01% or less, the balance is made of iron and inevitable impurities, and in the chemical composition of the steel sheet, the total of Si and Al is 1.0% or more.
- the plate thickness central part which is 4.0% or less and is a plate thickness range of 5/8 to 3/8, ⁇ 100 ⁇ ⁇ 011>, ⁇ 116 ⁇ ⁇ 110>, ⁇ 114 ⁇ ⁇ 110>, ⁇ 112 ⁇ ⁇ 110>, ⁇ 223 ⁇ ⁇ 110>, which is the polar density represented by the arithmetic average of the polar densities of each crystal orientation ⁇ 100 ⁇ ⁇ 01 >- ⁇ 223 ⁇ ⁇ 110> orientation group has an average pole density of 1.0 or more and 6.5 or less, and ⁇ 332 ⁇ ⁇ 113> crystal orientation pole density of 1.0 or more and 5.0
- a plurality of crystal grains are present in the microstructure of the steel sheet, and this microstructure has an area ratio of residual austenite of 2% to 30%, ferrite of 20% to 50%, bainite.
- the area ratio is limited to 20% or less of pearlite and 20% or less of martensite
- rC which is a Rankford value perpendicular to the rolling direction
- R30 which is a Rankford value in a direction that is 0.70 or more and 1.10 or less and that forms 30 ° with respect to the rolling direction, is 0.70 or more and 1.10 or less.
- the chemical composition of the steel sheet is further, by mass%, Ti: 0.001% or more and 0.2% or less, Nb: 0.001% or more and 0.2% or less, V: 0.001% to 1.0%, W: 0.001% to 1.0%, Cu: 0.001% to 2.0%, B: 0.0001% to 0.005%, Mo: 0.001% to 1.0%, Cr: 0.001% to 2.0%, As: 0.0001% to 0.00% 50% or less, Mg: 0.0001% or more and 0.010% or less, REM: 0.0001% or more and 0.1% or less, Ca: 0.0001% or more and 0.010% or less, Ni: 0.00. 001% to 2.0%, Co: 0.0001% to 1.0%, Sn: .0001% or more and 0.2% or less, Zr: 0.0001% or more and may contain one or more selected from 0.2% or less.
- the volume average diameter of the crystal grains may be 1 ⁇ m or more and 4 ⁇ m or less.
- the average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups is 1.0 or more and 5.0 or less.
- the polar density of the crystal orientation of ⁇ 332 ⁇ ⁇ 113> may be 1.0 or more and 4.0 or less.
- a distance L between nearest crystal grains to at least 100 crystal grains of the retained austenite and the martensite may be 5 ⁇ m or less.
- T1 + 30 ° C or more and T + 200 ° C. includes a mass reduction path more than 30% of rolling reduction in a temperature range of less, the cumulative rolling reduction in the temperature range of T1 + 30 ° C. or more and T1 + 200 ° C. or less 50% or more, Ar 3 ° C. or more and less than T1 + 30 ° C.
- the steel is subjected to a second hot rolling in which the cumulative rolling reduction in the temperature range is limited to 30% or less and the rolling end temperature is Ar 3 ° C or higher; the final pass of the large rolling passes;
- the steel is subjected to primary cooling so that the waiting time t from the completion to the start of cooling satisfies Equation 2; average cooling of 10 to 100 ° C./second to a temperature T 3 in the range of 630 ° C. to 800 ° C. Cooling the steel at a speed; holding the steel in a temperature range of 630 ° C. or more and 800 ° C. or less for 1 second or more and 20 seconds or less, or from the temperature T3 to less than the temperature T3 and 550 ° C.
- T1 850 + 10 ⁇ ([C] + [N]) ⁇ [Mn] (Formula 1)
- [C], [N] and [Mn] are mass percentages of the amounts of C, N and Mn in the steel, respectively.
- t1 is represented by the following formula 3.
- Tf is the temperature in degrees Celsius of the steel at the completion of the final pass
- P1 is a percentage of the rolling reduction in the final pass.
- the steel further has, as the chemical composition, mass%, Ti: 0.001% to 0.2%, Nb: 0. 0.001% to 0.2%, V: 0.001% to 1.0%, W: 0.001% to 1.0%, Cu: 0.001% to 2.0% %: B: 0.0001% to 0.005%, Mo: 0.001% to 1.0%, Cr: 0.001% to 2.0%, As: 0.0001 % To 0.50%, Mg: 0.0001% to 0.010%, REM: 0.0001% to 0.1%, Ca: 0.0001% to 0.010% Ni: 0.001% or more and 2.0% or less, Co: 0.0001% or more and 1.
- the temperature calculated by the following equation 4 may be T1.
- T1 850 + 10 ⁇ ([C] + [N]) ⁇ [Mn] + 350 ⁇ [Nb] + 250 ⁇ [Ti] + 40 ⁇ [B] + 10 ⁇ [Cr] + 100 ⁇ [Mo] + 100 ⁇ [V] (Formula 4) )
- [C], [N], [Mn], [Nb], [Ti], [B], [Cr], [Mo] and [V] are respectively C, N, It is a mass percentage of Mn, Nb, Ti, B, Cr, Mo and V amount.
- the waiting time t seconds may further satisfy the following formula 5 using t1.
- t ⁇ t1 (Formula 5)
- the waiting time t seconds may further satisfy the following formula 6 using the t1.
- an average cooling rate is 50 ° C./second or more, and the steel temperature at the start of cooling And the steel temperature at the end of cooling may be 40 ° C. or more and 140 ° C. or less, and the steel temperature at the end of cooling may be T1 + 100 ° C. or less.
- the temperature change rate is ⁇ 40 ° C./h or more and 40 ° C./h or less in the temperature range control. There may be.
- the primary cooling may be performed between rolling stands.
- high strength hot rolling excellent in local deformability such as bendability, stretch flangeability, burring workability, hole expansibility and the like, having low orientation dependency of formability and excellent ductility.
- a steel plate and a manufacturing method thereof can be provided. If this steel plate is used, the industrial contribution is extremely remarkable, particularly in that it is possible to achieve both weight reduction and collision safety of the automobile.
- the hole expandability and bendability such as inclusion control, precipitate refinement, homogenization of microstructure, single-phase structure control and reduction of hardness difference between microstructures, etc. It was improved by.
- these technologies alone must limit the main organizational structure.
- Nb, Ti, or the like which is a representative element that greatly contributes to an increase in strength, is added to increase the strength, the anisotropy becomes extremely large. Therefore, problems such as sacrificing other formability factors or limiting the direction in which the blank is taken before forming occur, and the use of the steel sheet is limited.
- the amount of retained austenite and the amount of C in the retained austenite are increased by increasing the concentration of C in the austenite during the annealing process, thereby improving the tensile properties.
- the present inventors have investigated and examined the microstructure refinement and the texture control in the hot rolling process in order to improve the hole expandability and bending workability in such a TRIP steel sheet. .
- the local deformability of the TRIP steel sheet is sufficiently improved by controlling the pole density of the crystal orientation described later.
- the inventors of the present invention in particular, rC that is a Rankford value (r value) in a direction perpendicular to the rolling direction and r30 that is a Rankford value (r value) in a direction that forms an angle of 30 ° with the rolling direction. It has been clarified that the local deformability of the TRIP steel sheet is drastically improved.
- Polar density of crystal orientation (D1 and D2): In the hot-rolled steel sheet according to the present embodiment, as the pole density of two types of crystal orientations, a thickness range of 5/8 to 3/8 (from the steel sheet surface to the steel sheet thickness direction (depth direction) Average of ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups with respect to the sheet thickness section parallel to the rolling direction at the sheet thickness central portion, which is a range separated by a distance of 5/8 to 3/8)
- the pole density D1 hereinafter may be abbreviated as the average pole density
- the pole density D2 of the crystal orientation ⁇ 332 ⁇ ⁇ 113> are controlled.
- the average pole density is a characteristic point (orientation accumulation degree, texture development degree) of a particularly important texture (crystal orientation of crystal grains in the microstructure).
- the average pole density is the phase of pole density in each crystal orientation of ⁇ 100 ⁇ ⁇ 011>, ⁇ 116 ⁇ ⁇ 110>, ⁇ 114 ⁇ ⁇ 110>, ⁇ 112 ⁇ ⁇ 110>, ⁇ 223 ⁇ ⁇ 110>. It is the pole density expressed as an arithmetic mean.
- Electron Back Scattering Diffraction (EBSD) or X-ray diffraction is performed on the cross section at the thickness center in the thickness range of 5/8 to 3/8, and the electron diffraction intensity or X-ray diffraction intensity in each direction for a random sample.
- the average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups can be obtained from the intensity ratios. If the average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups is 6.5 or less, d / RmC (plate thickness d is required for machining the undercarriage part and the skeleton part).
- the index divided by the minimum bending radius RmC (bending in the C direction) can satisfy 1.5 or more. This condition is in particular that the tensile strength TS, the hole expansion ratio ⁇ , and the elongation EL satisfy two conditions required for the undercarriage member, namely TS ⁇ ⁇ ⁇ 30000 and TS ⁇ EL ⁇ 14000.
- the average pole density is 5.0 or less, the ratio of the minimum bending radius Rm45 of 45 ° direction bending to the minimum bending radius RmC of C direction bending, which is an index of orientation dependency (isotropic property) of formability. (Rm45 / RmC) decreases, and a high local deformability independent of the bending direction can be secured. Therefore, the average pole density is preferably 6.5 or less, and preferably 5.0 or less. When better hole expansibility and small critical bending properties are required, the average pole density is more desirably less than 4.0, and even more desirably less than 3.0.
- the average pole density is preferably 1.0 or more.
- the pole density of the crystal orientation of ⁇ 332 ⁇ ⁇ 113> in the central portion of the plate thickness that is a plate thickness range of 5/8 to 3/8 is 5.0 or less.
- This condition is one condition in which the steel sheet satisfies d / RmC ⁇ 1.5.
- the tensile strength TS, the hole expansion ratio ⁇ , and the elongation EL are the two required for the suspension member. It is also a condition for satisfying both the conditions, that is, TS ⁇ ⁇ ⁇ 30000 and TS ⁇ EL ⁇ 14000.
- the pole density is 4.0 or less, TS ⁇ ⁇ and d / RmC can be further increased.
- the above pole density is desirably 4.0 or less, and more desirably 3.0 or less.
- the pole density is more than 5.0, the anisotropy of the mechanical properties of the steel sheet becomes extremely strong. As a result, the local deformability only in a specific direction is improved, but the local deformability in a direction different from that direction is significantly deteriorated. Therefore, as shown in FIG. 2, in this case, the steel sheet cannot reliably satisfy d / RmC ⁇ 1.5.
- this pole density is less than 1.0, there is a concern about deterioration of local deformability. Therefore, it is preferable that the pole density of the ⁇ 332 ⁇ ⁇ 113> crystal orientation is 1.0 or more.
- the pole density is synonymous with the X-ray random intensity ratio.
- the X-ray random intensity ratio is obtained by measuring the diffraction intensity (X-rays and electrons) of a standard sample that does not accumulate in a specific orientation and the diffraction intensity of the specimen by the X-ray diffraction method under the same conditions. It is a numerical value obtained by dividing the diffraction intensity of the obtained specimen by the diffraction intensity of the standard sample. This extreme density can be measured using X-ray diffraction, EBSD (Electron Back Scattering Diffraction), or electronic channeling.
- EBSD Electro Back Scattering Diffraction
- the pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups is a plurality of pole figures among ⁇ 110 ⁇ , ⁇ 100 ⁇ , ⁇ 211 ⁇ , ⁇ 310 ⁇ pole figures measured by these methods.
- ODF three-dimensional texture
- the steel plate is reduced to a predetermined thickness by mechanical polishing, and then the strain is removed by chemical polishing, electrolytic polishing, etc. and at the same time 5/8 of the plate thickness.
- the sample density may be measured according to the method described above by adjusting the sample so that an appropriate surface including the range of ⁇ 3 / 8 becomes the measurement surface.
- the steel plate satisfies the above-mentioned pole density, so that the local deformability is further improved.
- the material at the central portion of the plate thickness generally represents the material characteristics of the entire steel plate. Therefore, the average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation group and the pole density of the crystal orientation of ⁇ 332 ⁇ ⁇ 113> in the central portion of the thickness of 5/8 to 3/8 It prescribes.
- ⁇ hkl ⁇ ⁇ uvw> indicates that the normal direction of the plate surface is parallel to ⁇ hkl> and the rolling direction is parallel to ⁇ uvw> when the sample is collected by the above method.
- the crystal orientation is usually expressed as (hkl) or ⁇ hkl ⁇ in the direction perpendicular to the plate surface and [uvw] or ⁇ uvw> in the direction parallel to the rolling direction.
- ⁇ Hkl ⁇ ⁇ uvw> is a general term for equivalent planes, and (hkl) [uvw] refers to individual crystal planes.
- the body-centered cubic structure (bcc structure) is targeted, for example, (111), ( ⁇ 111), (1-11), (11-1), ( ⁇ 1-11) ), (-11-1), (1-1-1), and (-1-1-1) are equivalent and cannot be distinguished. In such a case, these orientations are collectively referred to as ⁇ 111 ⁇ planes. Since the ODF display is also used for displaying the orientation of other crystal structures with low symmetry, in the ODF display, the individual orientation is generally displayed as (hkl) [uvw]. , ⁇ Hkl ⁇ ⁇ uvw> and (hkl) [uvw] are synonymous.
- R value (rC) in the direction perpendicular to the rolling direction The r value (Rankford value) of this steel sheet is important in this embodiment. That is, as a result of intensive studies by the present inventors, as shown in FIG. 3, by making the above-mentioned pole densities within the above range and at the same time making rC 0.70 or more, good hole expansibility and bending We found that we can get sex. For this reason, rC is preferably 0.70 or more. The upper limit of rC is preferably 1.10 or less in order to obtain better hole expansibility and bendability.
- R value (r30) in a direction forming 30 ° with respect to the rolling direction The r value (Rankford value) of this steel sheet is important in this embodiment. That is, as a result of intensive studies by the present inventors, as shown in FIG. 4, by making each of the above-mentioned pole densities within the above range and at the same time r30 being 1.10 or less, good hole expansibility and bending are achieved. We found that we can get sex. Therefore, r30 is preferably 1.10 or less. The lower limit of r30 is preferably 1.10 in order to obtain better hole expansibility and bendability.
- the above r values are evaluated by a tensile test using a JIS No. 5 tensile test piece.
- the r value may be evaluated in a range where the tensile strain is in the range of 5 to 15% and corresponds to uniform elongation.
- the basic microstructure of the hot-rolled steel sheet according to the present embodiment is composed of ferrite, bainite, and retained austenite.
- pearlite and martensite in addition to this basic microstructure component (in place of a part of ferrite, bainite and retained austenite), pearlite and martensite (including tempered martensite) are included as necessary or unavoidable. 1) or more) may be contained in the microstructure as a component of the selective microstructure. In the present embodiment, each microstructure is evaluated by the area ratio.
- Ferrite and bainite are essential for improving ductility due to the TRIP effect in order to concentrate C in retained austenite. Furthermore, ferrite and bainite contribute to improvement of hole expansibility. It is possible to change the fraction of ferrite and bainite depending on the strength level targeted for development, but it is excellent by making ferrite 20% to 50% and bainite 10% to 60%. The ductility and hole expandability can be obtained. Therefore, ferrite is 20% or more and 50% or less, and bainite is 10% or more and 60% or less.
- Residual austenite is a structure that enhances ductility, particularly uniform elongation, by transformation-induced plasticity, and requires a retained austenite of 2% or more in area ratio.
- retained austenite is transformed into martensite by processing, which contributes to improvement in strength. The higher the area ratio of retained austenite, the better.
- the upper limit of the area ratio of retained austenite is set to 30% or less.
- the retained austenite is preferably 3% or more, more preferably 5% or more, and most preferably 8% or more.
- the microstructure may contain 20% of pearlite and martensite (including tempered martensite).
- pearlite and martensite including tempered martensite.
- the workability and local deformability of the steel sheet decrease, or the utilization rate of C that generates retained austenite decreases. Therefore, in the microstructure, pearlite is limited to 20% or less, and martensite is limited to 20% or less.
- the area ratio of austenite can be determined from the diffraction intensity obtained by performing X-ray diffraction on a plane parallel to the plate surface in the vicinity of the 1/4 plate thickness position.
- the area ratio of ferrite, pearlite, bainite, and martensite is within the range of 1/8 to 3/8 thickness (that is, the thickness range centered at 1/4 thickness position). It can be determined from an image obtained by observation with a microscope (FE-SEM: Field Emission Scanning Electron Microscope). In this FE-SEM observation, a sample is taken so that a plate thickness cross section parallel to the rolling direction of the steel plate becomes the observation surface, and polishing and nital etching are performed on this observation surface.
- the microstructure (component) of the steel sheet may be significantly different from other parts due to decarburization and Mn segregation, respectively. For this reason, in the present embodiment, the microstructure is observed based on the 1 ⁇ 4 thickness position.
- the size of the crystal grains in the microstructure may be refined. Furthermore, by reducing the volume average diameter, the fatigue characteristics (fatigue limit ratio) required for automobile steel sheets and the like are improved. Since the influence of the number of coarse grains on elongation is higher than that of fine grains, the elongation is more strongly correlated with the volume average diameter calculated by the weighted average of the volume than the number average diameter. Therefore, in order to obtain the above effect, the volume average diameter is 1 to 15 ⁇ m, preferably 1 to 9.5 ⁇ m, and more preferably 1 to 4 ⁇ m.
- the volume average diameter when the volume average diameter is reduced, local strain concentration occurring at the micro order is suppressed, strain at the time of local deformation can be dispersed, and elongation, particularly uniform elongation, is improved.
- the grain boundary that becomes a barrier to dislocation motion can be controlled appropriately, and this grain boundary acts on repeated plastic deformation (fatigue phenomenon) caused by the dislocation motion, thereby improving fatigue characteristics. .
- each crystal grain can be determined as follows.
- the pearlite is specified by observing the structure with an optical microscope.
- the grain units of ferrite, austenite, bainite, and martensite are specified by EBSD. If the crystal structure of the region determined by EBSD is a face-centered cubic structure (fcc structure), this region is determined to be austenite. Further, if the crystal structure of the region determined by EBSD is a body-centered cubic structure (bcc structure), this region is determined as one of ferrite, bainite, and martensite.
- Ferrite, bainite, and martensite can be identified by using the KAM (Kernel Average Missoriation) method equipped in EBSP-OIM (registered trademark, Electron Back Scatter Diffraction Pattern-Orientation Image Microscopy).
- KAM Kernel Average Missoriation
- EBSP-OIM Electron Back Scatter Diffraction Pattern-Orientation Image Microscopy
- the second approximation using all 12 pixels (19 pixels in total), or the third approximation using all 18 pixels outside these 12 pixels (total 37 pixels) the orientation difference between each pixel And the average value obtained is determined as the value of the center pixel, and such an operation is performed on the entire pixel.
- a map expressing the orientation change in the grain can be created. This map represents a strain distribution based on local orientation changes in the grains.
- the azimuth difference between adjacent pixels is calculated by the third approximation.
- the grain size of ferrite, bainite, martensite, and austenite is measured, for example, by performing the above-mentioned orientation measurement at a measurement step of 0.5 ⁇ m or less at a magnification of 1500 times, and at a position where the orientation difference between adjacent measurement points exceeds 15 °. It is obtained by defining the boundary (this grain boundary is not necessarily a general grain boundary) and calculating the equivalent circle diameter.
- the crystal grain size of pearlite can be calculated by applying image processing methods such as binarization and cutting to the image obtained by the optical microscope. it can.
- the ratio of the area occupied by grains (coarse grains) having a grain size exceeding 20 ⁇ m per unit area (coarse grain area ratio) is 10% for all the components of the microstructure. Restrict to the following. As the number of large grains increases, the tensile strength decreases and the local deformability also decreases. Therefore, it is preferable to make the crystal grains as fine as possible. In addition, since bendability is improved when all crystal grains are uniformly and equivalently strained, local crystal grain strain can be suppressed by limiting the amount of coarse grains.
- the standard deviation of the distance L MA [ ⁇ m] between crystal grains (residual austenite or martensite) closest to each other among the grains of retained austenite and martensite may be set to 5 ⁇ m.
- the distance LMA may be measured for at least 100 residual austenite and martensite grains to obtain a standard deviation of the distance LMA .
- C 0.02% or more and 0.5% or less C is essential in order to secure high strength and secure retained austenite. In order to obtain a sufficient amount of retained austenite, a C amount of 0.02% or more is required. On the other hand, if the steel sheet contains excessive C, the weldability is impaired, so the upper limit of the C content is set to 0.5% or less. In the case of further improving the strength and elongation, the C content is preferably 0.05% or more, more preferably 0.06% or more, and most preferably 0.08% or more. . Moreover, when improving weldability more, it is preferable that C amount is 0.45% or less, and it is more preferable that it is 0.40% or less.
- Si 0.001% or more and 4.0% or less
- Si is a deoxidizer, and preferably contains 0.001% or more of Si in the steel.
- Si stabilizes ferrite during temperature control after hot rolling, and suppresses cementite precipitation after winding (during bainite transformation). Therefore, Si increases the C concentration of austenite and contributes to securing retained austenite. The effect increases as the amount of Si increases.
- the upper limit of Si content is 4.0% or less.
- the Si amount is preferably 0.02% or more, more preferably 0.20% or more, and 0.50% or more. Most preferably it is.
- the Si content is preferably 3.5% or less, and more preferably 3.0% or less.
- Mn 0.001% or more and 4.0% or less
- Mn is an element that stabilizes austenite and improves hardenability. In order to ensure sufficient hardenability, 0.001% or more of Mn needs to be included in the steel. On the other hand, if Mn is added excessively to the steel, the ductility is impaired, so the upper limit of the Mn content is 4.0%. In order to ensure higher hardenability, the amount of Mn is preferably 0.1% or more, more preferably 0.5% or more, and most preferably 1.0% or more. Moreover, when ensuring higher ductility, it is preferable that the amount of Mn is 3.8% or less, and it is more preferable that it is 3.5% or less.
- P 0.15% or less
- P is an impurity, and if P is excessively contained in steel, ductility and weldability are impaired. Therefore, the upper limit of the P content is 0.15% or less.
- P acts as a solid solution strengthening element, but is inevitably contained in the steel, so the lower limit of the amount of P is not particularly limited and is 0%. In consideration of current general refining (including secondary refining), the lower limit of the P amount may be 0.001%.
- the P content is preferably 0.12% or less, and more preferably 0.10% or less.
- S 0.03% or less S is an impurity.
- the upper limit of S content is 0.03%.
- the lower limit of the amount of S is not particularly limited, and is 0%. In consideration of the current general refining (including secondary refining), the lower limit of the amount of S may be 0.0005%.
- the S content is preferably 0.020% or less, and more preferably 0.015% or less.
- O 0.01% or less
- O (oxygen) is an impurity.
- the upper limit of the O amount is 0.01%.
- the lower limit of the amount of O is not particularly limited and is 0%. In consideration of current general refining (including secondary refining), the lower limit of the O amount may be 0.0005%.
- Al 0.001% or more and 4.0% or less
- Al is a deoxidizer, and considering the current general refining (including secondary refining), the steel contains 0.001% or more of Al. It is preferable.
- Al stabilizes ferrite during temperature control after hot rolling, and suppresses cementite precipitation during bainite transformation. Therefore, Al increases the C concentration of austenite and contributes to securing retained austenite. The effect increases as the amount of Al increases. However, when Al is excessively added to the steel, surface properties, paintability, and weldability deteriorate. Therefore, the upper limit of the Al amount is set to 2.0%.
- the Al content is preferably 0.005% or more, and more preferably 0.01% or more.
- the Al content is preferably 3.5% or less, and more preferably 3.0% or less.
- N 0.01% or less N is an impurity, and if the amount of N exceeds 0.01%, ductility deteriorates. Therefore, the upper limit of the N amount is 0.01% or less.
- the lower limit of the N amount is not particularly limited and is 0%. In consideration of current general refining (including secondary refining), the lower limit of the N amount may be 0.0005%. In order to further increase the ductility, the N content is preferably 0.005% or less.
- Si + Al 1.0% or more and 4.0% or less
- Si and Al stabilize ferrite during temperature control after hot rolling, and suppress cementite precipitation after winding (during bainite transformation). Therefore, these elements increase the C concentration of austenite and contribute to securing retained austenite. Therefore, the total of the Si amount and the Al amount is preferably 1.0% or more. However, if these elements are excessively added to the steel, the surface properties, paintability, weldability and the like deteriorate, so the total amount of Si and Al is 4.0% or less. In the case of further ensuring surface properties, paintability, weldability and the like, the total is preferably 3.5% or less, and more preferably 3.0% or less.
- the above chemical elements are the basic components (basic elements) of the steel in the present embodiment, the basic elements are controlled (contained or restricted), and the chemical composition consisting of iron and unavoidable impurities as the balance is Basic composition.
- the following chemical elements may be further contained in the steel as necessary.
- these selection elements are inevitably mixed in the steel (for example, an amount less than the lower limit of the amount of each selection element), the effect in the present embodiment is not impaired.
- the hot-rolled steel sheet according to the present embodiment has Ti, Nb, B, Mg, REM, Ca, Mo, Cr as selective elements in order to improve local deformability by, for example, inclusion control or precipitate refinement.
- V, W, Ni, Cu, Co, Sn, Zr, As may be included.
- fine carbonitrides are preferably generated.
- the addition of Ti, Nb, V, W, and Cu is effective, and the steel sheet may contain one or more of these as required.
- the Ti amount is 0.001% or more, the Nb amount is 0.001% or more, the V amount is 0.001% or more, and the W amount is It is desirable that 0.001% or more and the amount of Cu be 0.001% or more.
- the amount is limited to 0.2% or less, the Nb amount is 0.2% or less, the V amount is 1.0% or less, the W amount is 1.0% or less, and the Cu amount is limited to 2.0% or less.
- the lower limits of the amounts of Ti, Nb, V, W and Cu are all 0%.
- the B content is preferably 0.0001% or more
- the Mo content and the Cr content are 0.001% or more
- the As content is 0.0001% or more.
- the upper limit of B amount is 0.005%
- the upper limit of Mo amount is 1.0%
- the upper limit of Cr amount is 2.0%
- the upper limit of As amount is limited to 0.50%.
- Mg, REM (Rare Earth Metal), and Ca are important selection elements for controlling the inclusions to be harmless and improving the local deformability of the steel sheet. Therefore, if necessary, one or more of Mg, REM, and Ca may be added to the steel.
- the lower limit of each chemical element is preferably 0.0001%.
- the upper limit of the amount of each chemical element is 0.010% or less for Mg, 0.1% or less for REM, The amount of Ca is limited to 0.010% or less.
- the lower limits of the amounts of Mg, REM and Ca are all 0%.
- Ni, Co, Sn, and Zr are selective elements that increase the strength, and if necessary, one or more of these chemical elements may be added to the steel.
- the Ni amount is 0.001% or more
- the Co amount is 0.0001% or more
- the Sn amount is 0.0001% or more
- the Zr amount is 0.0001% or more.
- the Ni content is 2.0% or less
- the Co content is 1.0% or less
- Sn is 1.0% or less
- the amount is limited to 0.2% or less
- the Zr amount is limited to 0.2%.
- the lower limits of the amounts of Ni, Co, Sn and Zr are all 0%.
- the hot-rolled steel sheet according to the present embodiment includes the above-described basic element, and the balance is selected from the chemical composition composed of Fe and inevitable impurities, or the above-described basic element and the above-described selective element. It has at least one kind, and the balance has a chemical composition consisting of iron and inevitable impurities.
- the hot-rolled steel sheet according to this embodiment may be surface-treated.
- surface treatment such as electroplating, hot dipping, vapor deposition plating, alloying treatment after plating, organic film formation, film lamination, organic / inorganic salt treatment, non-chromate treatment (non-chromate treatment)
- the rolled steel sheet may be provided with various coatings (film or coating).
- the hot-rolled steel sheet may have a hot-dip galvanized layer or an alloyed hot-dip galvanized layer on its surface. Even if the hot-rolled steel sheet is provided with the above-described coating, the local deformability can be sufficiently maintained.
- the thickness of the hot-rolled steel sheet is not particularly limited, but may be, for example, 1.5 to 10 mm, or 2.0 to 10 mm.
- the strength of the hot-rolled steel sheet is not particularly limited, and for example, the tensile strength may be 440 to 1500 MPa.
- the hot-rolled steel sheet according to this embodiment can be applied to all uses of high-strength steel sheets, and the local deformability such as bending workability and hole expansibility of the high-strength steel sheets is dramatically improved.
- the direction of bending the hot-rolled steel sheet is not particularly limited because it varies depending on the processed parts.
- the same characteristics are obtained in any bending direction, and the hot-rolled steel sheet can be applied to composite forming including processing modes such as bending, stretching, and drawing.
- the production method preceding hot rolling is not particularly limited.
- various secondary refining can be performed subsequent to smelting and refining in a blast furnace, electric furnace, converter, etc., and steel satisfying the above chemical composition can be melted to obtain steel (molten steel).
- the steel can be cast by a casting method such as a normal continuous casting method, an ingot method, or a thin slab casting method.
- the steel may be once cooled to a low temperature (for example, room temperature) and reheated, and then the steel may be hot-rolled, or the steel immediately after casting (cast slab) may be continuously It may be hot rolled.
- the austenite grain size before finish rolling is small, and if the average austenite grain size before finish rolling is 200 ⁇ m or less, it is effective to obtain sufficient local deformability.
- rough rolling in order to obtain the average austenite grain size before finish rolling of 200 ⁇ m or less, rough rolling (first step) in a temperature range of 1000 ° C. or more and 1200 ° C. or less (preferably 1150 ° C. or less) is used.
- the steel may be rolled once or more at a rolling reduction of 40% or more by hot rolling.
- the finer austenite grains can be obtained. For example, it is desirable to control to an average austenite grain size of 100 ⁇ m or less in rough rolling. In order to perform this grain size control, rolling with a rolling reduction of 40% or more in one pass is performed twice (two passes) or more. Good. However, in rough rolling, by reducing the reduction rate of one pass to 70% or less, or limiting the number of reductions (number of passes) to 10 times or less, the concern about the decrease in temperature and excessive generation of scale is reduced. Can be made. Therefore, in rough rolling, the rolling reduction of one pass may be 70% or less, and the number of rolling (number of passes) may be 10 or less. Thus, reducing the austenite grain size before finish rolling promotes recrystallization of austenite in subsequent finish rolling, and is effective in improving local deformability.
- the austenite grain boundary after rough rolling that is, before finish rolling
- the steel sheet is cooled at an average cooling rate of 10 ° C./s or more.
- the cross section of the plate piece collected from the steel plate obtained by cooling is etched to make the austenite grain boundary in the microstructure stand up and measured with an optical microscope.
- the particle size of austenite is measured by image analysis or a cutting method with respect to 20 or more fields of view at a magnification of 50 times or more, and each austenite particle size is averaged to obtain an average austenite particle size.
- the sheet bars may be joined and finish rolling may be performed continuously.
- the coarse bar may be wound once in a coil shape, stored in a cover having a heat retaining function as necessary, and rewound again before joining.
- the finish rolling after the rough rolling is performed according to the following formula 7 depending on the chemical composition (mass%) of the steel. Rolling is controlled based on a determined temperature T1 (° C.).
- T1 850 + 10 ⁇ ([C] + [N]) ⁇ [Mn] + 350 ⁇ [Nb] + 250 ⁇ [Ti] + 40 ⁇ [B] + 10 ⁇ [Cr] + 100 ⁇ [Mo] + 100 ⁇ [V] (Formula 7 )
- [C], [N], [Mn], [Nb], [Ti], [B], [Cr], [Mo], and [V] are C, N, It is a mass percentage of Mn, Nb, Ti, B, Cr, Mo and V amount.
- the amount of chemical element (chemical component) not included in Equation 7 is calculated as 0%. Therefore, in the basic composition containing only the above basic components, the following formula 8 may be used instead of the above formula 7.
- T1 850 + 10 ⁇ ([C] + [N]) ⁇ [Mn] (Formula 8)
- T1 850 + 10 ⁇ ([C] + [N]) ⁇ [Mn]
- Formula 8 it is necessary to set the temperature calculated by Formula 7 instead of the temperature calculated by Formula 8 to T1 (° C.).
- T1 + 30 ° C. or higher and T1 + 200 ° C. or lower preferably a temperature range of T1 + 50 ° C. and T1 + 100 ° C. or lower
- a large reduction ratio In the temperature range of Ar 3 ° C or higher and lower than T1 + 30 ° C, the rolling reduction is limited to a small range (including 0%).
- the local deformability of the final product can be enhanced.
- a large rolling reduction in the temperature range of T1 + 30 ° C. or more and T1 + 200 ° C. or less and limiting the rolling reduction in a temperature range of Ar 3 ° C. or more and less than T1 + 30 ° C., in a thickness range of 5/8 to 3/8.
- the average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation group and the pole density of the crystal orientation ⁇ 332 ⁇ ⁇ 113> in a central part of a certain plate thickness are sufficiently controlled to localize the final product. Deformability is dramatically improved.
- This temperature T1 itself has been determined empirically.
- the present inventors have empirically found through experiments that the temperature range in which recrystallization in the austenite region of each steel can be promoted can be determined based on the temperature T1.
- T1 + 30 ° C. or more and T1 + 200 ° C. or less is 50% or more.
- the cumulative rolling reduction is desirably 70% or more from the viewpoint of promoting recrystallization due to strain accumulation.
- the cumulative rolling reduction may be 90% or less.
- a large reduction pass with a reduction ratio of 30% or more in a temperature range of T1 + 30 ° C. or more and T1 + 200 ° C. or less is included. So that finish rolling is controlled.
- finish rolling at a temperature range of T1 + 30 ° C. or higher and T1 + 200 ° C. or lower, at least one reduction of a reduction ratio of 30% or more is performed.
- the reduction rate of the final pass in this temperature range is 30% or more, that is, the final pass is a large reduction pass.
- the final two-pass rolling reduction is preferably 30% or more.
- the rolling reduction of the large rolling pass (1 pass) is preferably 40% or more.
- it is good that the rolling reduction of a large rolling down pass (1 pass) is 70% or less.
- a more uniform recrystallized austenite can be obtained by suppressing the temperature rise (for example, 18 ° C. or lower) of the steel sheet between each rolling pass.
- the cumulative reduction ratio is 30% or less.
- the rolling reduction in the temperature range of Ar 3 ° C. or higher and less than T1 + 30 ° C. is large, the recrystallized austenite grains expand and local deformability deteriorates. That is, in the manufacturing conditions according to this embodiment, the austenite is uniformly and finely recrystallized in finish rolling to control the texture and r value of the hot rolled product and improve local deformability such as hole expandability and bendability. can do.
- the finally obtained hot-rolled steel sheet has an average pole density of the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups of 1.0 or more and 6.5 or less in the center portion of the plate thickness. It does not satisfy at least one of certain conditions, that is, the pole density of crystal orientation of ⁇ 332 ⁇ ⁇ 113> is 1.0 or more and 5.0 or less.
- finish rolling when rolling is performed in a temperature range higher than T1 + 200 ° C.
- the rolling reduction can be obtained by actual results or calculation from measurement of rolling load or sheet thickness.
- the rolling temperature (for example, each of the above temperature ranges) can be measured by an inter-stand thermometer, or can be calculated by a calculation simulation considering processing heat generation from line speed, rolling reduction, etc. (both actual measurement and calculation) It can be obtained by performing.
- the reduction ratio in one pass is the amount of reduction in one pass with respect to the inlet plate thickness before passing through the rolling stand (difference between the inlet plate thickness before passing through the rolling stand and the outlet plate thickness after passing through the rolling stand). The percentage.
- the cumulative reduction ratio is based on the inlet plate thickness before the first pass in rolling in each of the above temperature ranges, and the cumulative reduction amount relative to this reference (the inlet plate thickness before the first pass in rolling in each of the above temperature ranges and the above mentioned It is a percentage of the difference between the outlet plate thickness after the final pass in rolling in each temperature range.
- the Ar 3 temperature is obtained by the following formula 9.
- Ar 3 879.4 ⁇ 516.1 ⁇ [C] ⁇ 65.7 ⁇ [Mn] + 38.0 ⁇ [Si] + 274.7 ⁇ [P] (Formula 9)
- the hot rolling (finish rolling) performed as described above, when the hot rolling is finished at a temperature lower than Ar 3 (° C.), the steel is rolled in a two-phase region (two-phase temperature region) of austenite and ferrite. For this reason, the accumulation of crystal orientations in the ⁇ 100 ⁇ ⁇ 011> to ⁇ 223 ⁇ ⁇ 110> orientation groups becomes strong, and as a result, the local deformability is significantly deteriorated.
- the rolling end temperature of finish rolling is T1 ° C. or higher, the amount of strain in the temperature range of T1 ° C. or lower can be reduced to further reduce anisotropy, and as a result, the local deformability can be further increased. . Therefore, the finish temperature of finish rolling may be T1 ° C. or higher.
- the cooling (primary cooling) after the last large rolling reduction (rolling at the rolling stand) in the temperature range of T1 + 30 ° C. or more and T1 + 200 ° C. or less greatly affects the crystal grain size of the final product.
- this cooling makes it possible to control the crystal grains to have an equiaxed (uniform size) microstructure with few coarse grains.
- the final reduction pass in the hot rolling in the hot rolling is a reduction (pass) of a reduction rate of 30% or more in a temperature range of T1 + 30 ° C. or more and T1 + 200 ° C. or less).
- Tf in Equation 11 is the temperature (° C.) of the steel plate when the final pass of the large reduction pass is completed, and P1 is the reduction rate (%) in the final pass of the large reduction passes.
- operability for example, controllability of shape correction and secondary cooling
- primary cooling is preferably performed between rolling stands.
- the waiting time t exceeds the value on the right side of Formula 10 (2.5 ⁇ t1), the recrystallization is almost completed, but the crystal grains grow significantly and the crystal grain size increases. And the elongation decreases. Therefore, the waiting time t is 2.5 ⁇ t1 seconds or less.
- t1 0.001 ⁇ ((Tf ⁇ T1) ⁇ P1 / 100) 2 ⁇ 0.109 ⁇ ((Tf ⁇ T1) ⁇ P1 / 100) +3.1 (Formula 11)
- the waiting time t By further limiting the waiting time t to less than t1 seconds, crystal grain growth can be significantly suppressed.
- the volume average diameter of the final product can be controlled to 4 ⁇ m or less. As a result, even if recrystallization does not proceed sufficiently, the elongation of the steel sheet can be sufficiently improved, and at the same time, fatigue characteristics can be improved.
- the volume average diameter (for example, more than 4 ⁇ m) is increased as compared with the case where the waiting time t is less than t1 seconds. Since the recrystallization proceeds sufficiently and the crystal orientation is randomized, the elongation of the steel sheet can be sufficiently improved, and at the same time, the isotropic property can be greatly improved.
- the primary cooling described above can be performed between the rolling stands or after the last rolling stand. That is, after primary cooling, a low rolling reduction (for example, 30% or less (or less than 30%) in a temperature range of Ar 3 ° C or higher (for example, Ar 3 (° C) to T1 + 30 (or Tf) (° C)) )) Rolling may be performed.
- a low rolling reduction for example, 30% or less (or less than 30%) in a temperature range of Ar 3 ° C or higher (for example, Ar 3 (° C) to T1 + 30 (or Tf) (° C))
- Rolling may be performed.
- the change in cooling temperature which is the difference between the steel plate temperature (steel temperature) at the start of cooling in primary cooling and the steel plate temperature (steel temperature) at the end of cooling, is preferably 40 ° C. or higher and 140 ° C. or lower. Further, it is desirable that the steel plate temperature T2 at the end of the primary cooling is T1 + 100 ° C. or less. If this cooling temperature change is 40 ° C. or higher, the grain growth of recrystallized austenite grains can be further suppressed. If the change in cooling temperature is 140 ° C. or less, recrystallization can proceed more sufficiently, and the pole density can be further improved.
- the cooling temperature change by limiting the cooling temperature change to 140 ° C or lower, not only can the temperature of the steel sheet be controlled relatively easily, but also variant selection (avoidance of variant restrictions) can be controlled more effectively, further improving the texture development. It can also be suppressed. Therefore, in this case, the isotropic property can be further increased, and the orientation dependency of workability can be further reduced. Furthermore, when the steel plate temperature T2 at the end of the primary cooling is T1 + 100 ° C. or less, a more sufficient cooling effect can be obtained. By this cooling effect, crystal grain growth can be suppressed and an increase in austenite grain size can be further suppressed. Moreover, it is desirable that the average cooling rate in primary cooling is 50 ° C./second or more.
- the average cooling rate in the primary cooling is 50 ° C./second or more, the grain growth of the recrystallized austenite grains can be further suppressed.
- the upper limit of the average cooling rate is not particularly required, but the average cooling rate may be 200 ° C./second or less from the viewpoint of the plate shape.
- the steel is cooled at an average cooling rate of 10 to 100 ° C./second (secondary cooling) to a temperature T3 in the range of 630 ° C. or higher and 800 ° C. or lower, which is near the nose of the pro-eutectoid ferrite region. Thereafter, the steel is held in a temperature range of 630 ° C. or more and 800 ° C. or less for 1 second or more and 20 seconds or less, or 20 ° C./second or less from temperature T3 to a temperature in the range of less than T3 and 550 ° C. or more. Slowly cool at an average cooling rate. By such temperature control, a sufficient amount of ferrite can be easily obtained.
- the crystal grains can be refined by cooling to 630 ° C. or higher and 800 ° C. or lower at an average cooling rate of 10 ° C./second or higher.
- the holding time exceeds 20 seconds, the ferrite fraction becomes too high and the strength decreases.
- the holding time is less than 1 second, the amount of ferrite produced is insufficient.
- the temperature at which slow cooling is stopped is lower than 550 ° C., or if the cooling stop temperature before holding or slow cooling is less than 630 ° C., pearlite transformation may occur. Therefore, the temperature at which slow cooling is stopped is set to 550 ° C. or higher, and the cooling stop temperature before holding or slow cooling is set to 630 ° C. or higher.
- the steel is cooled and wound up to a temperature within the range of 350 to 500 ° C.
- the coil (steel) thus wound is subjected to a temperature range control in which the coil (steel) is held in a range of 350 to 500 ° C. for 30 to 300 minutes, and then the coil is air-cooled.
- the coiling temperature exceeds 500 ° C.
- the bainite transformation proceeds excessively.
- the coiling temperature is lower than 350 ° C., the bainite transformation is excessively suppressed, and the stabilization of residual austenite due to C concentration is not sufficient.
- martensitic transformation occurs during air cooling, and a sufficient amount of retained austenite cannot be obtained.
- the holding time at 350 ° C. to 500 ° C. is less than 30 minutes, the progress of bainite transformation is not sufficient and the retained austenite fraction decreases.
- the holding time exceeds 300 minutes cementite precipitates or the precipitated cementite grows, so that the desired retained austenite fraction cannot be obtained.
- the temperature change rate of the coil is -40 ° C./h or more and 40 ° C./h or less in this temperature range control, the temperature change in the coil is gradual, so the material in the coil is controlled more uniformly. be able to.
- a hot-rolled steel sheet having excellent local deformability can be obtained by the manufacturing method as described above.
- This skin pass rolling it is possible to prevent stretcher strain generated during processing and to correct the steel plate shape.
- surface treatment such as electroplating, hot dipping, vapor deposition, alloying after plating, organic film formation, film lamination, organic / inorganic salt treatment, non-chromic treatment, etc. is applied to the obtained hot-rolled steel sheet.
- a hot-dip galvanized layer or an alloyed hot-dip galvanized layer may be formed on the surface of the hot-rolled steel sheet. Even when the above surface treatment is performed, the local deformability can be sufficiently maintained.
- FIG. 6 shows a flowchart showing an outline of a method for manufacturing a hot-rolled steel sheet according to this embodiment.
- Tables 7 to 9 show the feature points and mechanical properties of the microstructure (including the texture).
- ⁇ , F, B, M, and P represent the area ratios of retained austenite, ferrite, bainite, martensite, and pearlite, respectively.
- f 20 , d V and ⁇ MA indicate the percentage of the area ratio of crystal grains (coarse grains) exceeding 20 ⁇ m, the volume average diameter of crystal grains, and the standard deviation of the above-mentioned distance L MA , respectively.
- the hole expansion rate ⁇ of the final product and the critical bending radius (d / RmC) by 90 ° V-bending were used.
- the tensile test (measurement of TS and EL), the bending test, and the hole expansion test were compliant with JIS Z 2241, JIS Z 2248 (V block 90 ° bending test), and the iron standard JFS T1001, respectively.
- JIS Z 2241 JIS Z 2248
- JFS T1001 the iron standard JFS T1001
- Production No. Nos. 1 to 14 and 25 to 34 satisfy the conditions of the present invention. Then, d / RmC, TS ⁇ ⁇ , and TS ⁇ EL of the obtained steel plate were excellent. In addition, d / RmC, TS ⁇ ⁇ , and TS ⁇ EL were further improved by further optimizing the manufacturing conditions. On the other hand, production No. In 15 to 24 and 35, the conditions of the present invention were not satisfied, so at least one of d / RmC, TS ⁇ ⁇ , and TS ⁇ EL of the obtained steel sheet was not sufficient.
- TRIP steel a hot-rolled steel sheet having excellent local deformability, less orientation dependency of formability, and excellent ductility, and a manufacturing method thereof are provided.
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Abstract
Description
本願は、2011年3月28日に、日本に出願された特願2011-070725号に基づき優先権を主張し、その内容をここに援用する。
本発明の主旨は、以下の通りである。
T1=850+10×([C]+[N])×[Mn] (式1)
ここで、[C]、[N]及び[Mn]は、それぞれ、前記鋼中のC、N及びMn量の質量百分率である。
t≦2.5×t1 (式2)
ここで、t1は下記式3で表される。
t1=0.001×((Tf-T1)×P1/100)2-0.109×((Tf-T1)×P1/100)+3.1 (式3)
ここで、Tfは前記最終パス完了時の前記鋼の摂氏温度であり、P1は前記最終パスでの圧下率の百分率である。
T1=850+10×([C]+[N])×[Mn]+350×[Nb]+250×[Ti]+40×[B]+10×[Cr]+100×[Mo]+100×[V] (式4)
ここで、[C]、[N]、[Mn]、[Nb]、[Ti]、[B]、[Cr]、[Mo]及び[V]は、それぞれ、前記鋼中のC、N、Mn、Nb、Ti、B、Cr、Mo及びV量の質量百分率である。
t<t1 (式5)
t1≦t≦t1×2.5 (式6)
まず、熱延鋼板の結晶方位の極密度について述べる。
本実施形態に係る熱延鋼板では、2種類の結晶方位の極密度として、5/8~3/8の板厚範囲(鋼板の表面から鋼板の板厚方向(深さ方向)に板厚の5/8~3/8の距離だけ離れた範囲)である板厚中央部における圧延方向に平行な板厚断面に対して、{100}<011>~{223}<110>方位群の平均極密度D1(以下では、平均極密度と省略する場合がある)と、{332}<113>の結晶方位の極密度D2とを制御している。
本実施形態では、平均極密度は、特に重要な集合組織(ミクロ組織中の結晶粒の結晶方位)の特徴点(方位集積度、集合組織の発達度)である。なお、平均極密度は、{100}<011>、{116}<110>、{114}<110>、{112}<110>、{223}<110>の各結晶方位の極密度の相加平均で表される極密度である。
5/8~3/8の板厚範囲である板厚中央部における断面に対してEBSD(Electron Back Scattering Diffraction)またはX線回折を行い、ランダム試料に対する各方位の電子回折強度またはX線回折強度の強度比を求め、この各強度比から{100}<011>~{223}<110>方位群の平均極密度を求めることができる。
この{100}<011>~{223}<110>方位群の平均極密度が6.5以下であれば、足回り部品や骨格部品の加工に必要とされるd/RmC(板厚dを最小曲げ半径RmC(C方向曲げ)で除した指標)が1.5以上を満たしうる。この条件は、特に、引張強度TSと、穴拡げ率λと、伸びELとが、足回り部材に必要とされる2つの条件、すなわちTS×λ≧30000及びTS×EL≧14000を満たすための一条件でもある。さらに、平均極密度が5.0以下であれば、成形性の方位依存性(等方性)の指標である、C方向曲げの最小曲げ半径RmCに対する45°方向曲げの最小曲げ半径Rm45の比率(Rm45/RmC)が低下し、曲げ方向に依存しない高い局部変形能を確保できる。そのため、平均極密度が、6.5以下であるとよく、5.0以下であることが好ましい。より優れた穴拡げ性や小さな限界曲げ特性を必要とする場合には、平均極密度は、より望ましくは4.0未満であり、さらに一層望ましくは3.0未満である。
{100}<011>~{223}<110>方位群の平均極密度が6.5超では、鋼板の機械的特性の異方性が極めて強くなる。その結果、特定の方向のみの局部変形能が改善するが、その方向とは異なる方向での局部変形能が著しく劣化する。そのため、図1に示すように、この場合には、鋼板が、d/RmC≧1.5を満足できなくなる。
さらに、上記極密度が4.0以下であれば、TS×λやd/RmCをさらに高めることができる。そのため、上記極密度は、望ましくは4.0以下であり、より望ましくは3.0以下である。この極密度が5.0超であると、鋼板の機械的特性の異方性が極めて強くなる。その結果、特定の方向のみの局部変形能が改善するが、その方向とは異なる方向での局部変形能が著しく劣化する。そのため、図2に示すように、この場合には、鋼板がd/RmC≧1.5を確実に満足できなくなる。
一方、この極密度が1.0未満になると、局部変形能の劣化が懸念される。そのため、{332}<113>の結晶方位の極密度が1.0以上であることが好ましい。
この鋼板のr値(ランクフォード値)は、本実施形態において重要である。すなわち、本発明者等が鋭意検討の結果、図3に示すように、上記各極密度を上記の範囲内にすると同時に、rCを0.70以上にすることにより、良好な穴拡げ性及び曲げ性を得ることができることを見出した。そのため、rCが0.70以上であるとよい。
rCの上限は、より優れた穴拡げ性及び曲げ性を得るためには、1.10以下であるとよい。
この鋼板のr値(ランクフォード値)は、本実施形態において重要である。すなわち、本発明者等が鋭意検討の結果、図4に示すように、上記各極密度を上記の範囲内にすると同時に、r30を1.10以下にすることにより、良好な穴拡げ性及び曲げ性を得ることができることを見出した。そのため、r30が1.10以下であるとよい。
r30の下限は、より優れた穴拡げ性及び曲げ性を得るためには、1.10であるとよい。
本実施形態に係る熱延鋼板の基本的なミクロ組織は、フェライトと、ベイナイトと、残留オーステナイトとからなる。本実施形態では、この基本的なミクロ組織の構成要素に加え(フェライト、ベイナイト、残留オーステナイトの一部の代わりに)、必要に応じてまたは不可避的に、パーライト、マルテンサイト(焼戻しマルテンサイトを含む)の1種以上を選択的なミクロ組織の構成要素としてミクロ組織中に含んでいてもよい。なお、本実施形態では、個々のミクロ組織を面積率により評価する。
また、フェライト、パーライト、ベイナイト及びマルテンサイトの面積率は、1/8~3/8の板厚範囲(すなわち、1/4の板厚位置が中心になる板厚範囲)を電界放射型走査電子顕微鏡(FE-SEM:Field Emission Scanning Electron Microscope)により観察し、得られた画像から決定することができる。このFE-SEM観察では、鋼板の圧延方向に平行な板厚断面が観察面になるように試料を採取し、この観察面に対して研磨及びナイタールエッチングを行っている。
なお、板厚方向について、鋼板表面近傍及び鋼板中心近傍では、それぞれ、脱炭及びMn偏析により鋼板のミクロ組織(構成要素)がその他の部分と大きく異なる場合がある。そのため、本実施形態では、1/4の板厚位置を基準としたミクロ組織の観察を行っている。
細粒に比べると粗大粒の数が伸びへ与える影響度が高いため、伸びは、個数平均径よりも体積の重み付け平均で算出される体積平均径と強く相関する。そのため、上記の効果を得る場合には、体積平均径が、1~15μm、望ましくは、1~9.5μm、さらに望ましくは、1~4μmであるとよい。
パーライトは、光学顕微鏡による組織観察により特定される。また、フェライト、オーステナイト、ベイナイト、マルテンサイトの粒単位は、EBSDにより特定される。EBSDにより判定された領域の結晶構造が面心立方構造(fcc構造)であれば、この領域をオーステナイトと判定する。また、EBSDにより判定された領域の結晶構造が体心立方構造(bcc構造)であれば、この領域をフェライト、ベイナイト、マルテンサイトのいずれかと判定する。フェライト、ベイナイト、マルテンサイトは、EBSP-OIM(登録商標、Electron Back Scatter Diffraction Pattern-Orientation Image Microscopy)に装備されているKAM(Kernel Average Misorientation)法を用いて識別することができる。KAM法では、測定データのうちのある正六角形のピクセル(中心のピクセル)とこのピクセルに隣り合う6個のピクセルを用いた第一近似(全7ピクセル)、もしくはこれら6個のピクセルのさらに外側の12個のピクセルも用いた第二近似(全19ピクセル)、もしくはこれら12個のピクセルのさらに外側の18個のピクセルも用いた第三近似(全37ピクセル)について、各ピクセル間の方位差を平均し、得られた平均値をその中心のピクセルの値に決定し、このような操作をピクセル全体に対して行う。このKAM法による計算を粒界を超えないように行うことにより、粒内の方位変化を表現するマップを作成できる。このマップは、粒内の局所的な方位変化に基づく歪みの分布を表している。
また、下記の粗大粒の面積率は、この方法により得られた粗大粒の面積率を測定対象の面積で除することにより得ることができる。
加えて、下記の距離LMAは、上記の方法(但し、EBSDが可能なFE-SEM)により得られた、オーステナイトとオーステナイト以外の粒との間の境界と、マルテンサイトとマルテンサイト以外の粒との間の境界とを使用して決定することができる。
Cは、高強度を確保し、かつ残留オーステナイトを確保するために必須である。十分な残留オーステナイト量を得るためには、0.02%以上のC量が必要となる。一方、鋼板がCを過剰に含有すると、溶接性を損なうため、C量の上限を0.5%以下とした。強度と伸びとをより向上させる場合には、C量が、0.05%以上であることが好ましく、0.06%以上であることがより好ましく、0.08%以上であることが最も好ましい。また、より溶接性を向上させる場合には、C量が、0.45%以下であることが好ましく、0.40%以下であることがより好ましい。
Siは脱酸剤であり、鋼中に0.001%以上のSiを含むことが好ましい。また、Siは、熱間圧延後の温度制御時にフェライトを安定化させ、かつ、巻き取り後(ベイナイト変態時)のセメンタイト析出を抑制する。そのため、Siは、オーステナイトのC濃度を高め、残留オーステナイトの確保に寄与する。Si量が多いほどその効果は大きくなるが、Siを過剰に鋼中に添加すると、表面性状、塗装性、溶接性などが劣化する。そのため、Si量の上限を4.0%以下とする。安定な残留オーステナイトを得る効果をSiによって十分発現させる場合には、Si量が、0.02%以上であることが好ましく、0.20%以上であることがより好ましく、0.50%以上であることが最も好ましい。また、表面性状、塗装性、溶接性などをさらに確保する場合には、Si量が、3.5%以下であることが好ましく、3.0%以下であることがより好ましい。
Mnは、オーステナイトを安定化させ、焼入れ性を高める元素である。十分な焼入れ性を確保するためには、鋼中に0.001%以上のMnを含む必要がある。一方、Mnを鋼中に過剰に添加すると、延性を損なうため、Mn量の上限を4.0%とする。より高い焼入れ性を確保するためには、Mn量が、0.1%以上であることが好ましく、0.5%以上であることがより好ましく、1.0%以上であることが最も好ましい。また、より高い延性を確保する場合には、Mn量が、3.8%以下であることが好ましく、3.5%以下であることがより好ましい。
Pは不純物であり、Pを過剰に鋼中に含有すると延性や溶接性を損なう。したがって、P量の上限を0.15%以下とする。なお、Pは、固溶強化元素として作用するが、不可避的に鋼中に含まれるため、P量の下限は、特に制限する必要がなく、0%である。また、現行の一般的な精錬(二次精錬を含む)を考慮すると、P量の下限は、0.001%であってもよい。延性及び溶接性をより高める場合には、P量が、0.12%以下であることが好ましく、0.10%以下であることがより好ましい。
Sは不純物であり、Sを過剰に鋼中に含有すると、熱間圧延によって伸張したMnSが生成し、延性及び穴拡げ性などの成形性が劣化する。したがって、S量の上限を0.03%とする。なお、Sは、不可避的に鋼中に含まれるため、S量の下限は、特に制限する必要がなく、0%である。また、現行の一般的な精錬(二次精錬を含む)を考慮すると、S量の下限は、0.0005%であってもよい。延性及び穴拡げ性をより高める場合には、S量が、0.020%以下であることが好ましく、0.015%以下であることがより好ましい。
O(酸素)は不純物であり、O量が0.01%を超えると、延性が劣化する。したがって、O量の上限を0.01%とする。なお、Oは、不可避的に鋼中に含まれるため、O量の下限は、特に制限する必要がなく、0%である。また、現行の一般的な精錬(二次精錬を含む)を考慮すると、O量の下限は、0.0005%であってもよい。
Alは脱酸剤であり、現行の一般的な精錬(二次精錬を含む)を考慮すると、鋼中に0.001%以上のAlを含むことが好ましい。また、Alは、熱間圧延後の温度制御時にフェライトを安定化させ、かつ、ベイナイト変態時のセメンタイト析出を抑制する。そのため、Alは、オーステナイトのC濃度を高め、残留オーステナイトの確保に寄与する。Al量が多いほどその効果は大きくなるが、Alを過剰に鋼中に添加すると、表面性状、塗装性、溶接性が劣化する。そのため、Al量の上限を2.0%とする。安定な残留オーステナイトを得る効果をAlによって十分に発現させる場合には、Al量が、0.005%以上であることが好ましく、0.01%以上であることがより好ましい。また、表面性状、塗装性、溶接性などをさらに確保する必要がある場合には、Al量が、3.5%以下であることが好ましく、3.0%以下であることがより好ましい。
Nは、不純物であり、N量が0.01%を超えると延性が劣化する。したがって、N量の上限を0.01%以下とする。なお、Nは、不可避的に鋼中に含まれるため、N量の下限は、特に制限する必要がなく、0%である。また、現行の一般的な精錬(二次精錬を含む)を考慮すると、N量の下限は、0.0005%であってもよい。より延性を高める場合には、N量が0.005%以下であることが好ましい。
これらの元素は、上述のように、脱酸剤である。また、Si、Alの両方とも、熱間圧延後の温度制御時にフェライトを安定化させ、かつ、巻き取り後(ベイナイト変態時)のセメンタイト析出を抑制する。そのため、これらの元素は、オーステナイトのC濃度を高め、残留オーステナイトの確保に寄与する。したがって、Si量とAl量との合計が1.0%以上であることが好ましい。しかし、これらの元素を過剰に鋼中に添加すると、表面性状、塗装性、溶接性などが劣化するので、Si量とAl量との合計を4.0%以下とする。表面性状、塗装性、溶接性などをさらに確保する場合には、この合計が、3.5%以下であることが好ましく、3.0%以下であることがより好ましい。
すなわち、本実施形態に係る熱延鋼板が、例えば介在物制御や析出物微細化により局部変形能を向上させるために、選択元素として、Ti、Nb、B、Mg、REM、Ca、Mo、Cr、V、W、Ni、Cu、Co、Sn、Zr、Asのうちいずれか1種以上を含有しても構わない。
優れた局部変形能を実現するためには、異方性が少ない極密度を有する集合組織(未発達の集合組織)を形成させ、rC及びr30を適切に制御することが重要である。製造された熱延鋼板について、各極密度、rC及びr30を制御するための製造条件の詳細を以下に記す。
局部変形能を高めるためには、仕上げ圧延前のオーステナイト粒径が小さいことが望ましく、仕上げ圧延前の平均オーステナイト粒径が200μm以下であれば十分な局部変形能を得るために効果的であることが判明した。
図5に示すように、この200μm以下の仕上げ圧延前の平均オーステナイト粒径を得るためには、1000℃以上かつ1200℃以下(好ましくは1150℃以下)の温度範囲での粗圧延(第1の熱間圧延)で40%以上の圧下率で1回以上鋼を圧延すればよい。
このように、仕上げ圧延前のオーステナイト粒径を小さくすることが、後々の仕上げ圧延でのオーステナイトの再結晶を促進し、局部変形能の改善に有効である。
粗圧延後のオーステナイト粒径を確認するためには、仕上げ圧延に入る前の鋼(鋼板)を可能な限り大きな冷却速度で急冷することが望ましい。例えば、10℃/s以上の平均冷却速度で鋼板を冷却する。さらに、冷却して得られたこの鋼板から採取した板片の断面をエッチングしてミクロ組織中のオーステナイト粒界を浮き立たせて光学顕微鏡にて測定する。この際、50倍以上の倍率での20以上の視野に対して、オーステナイトの粒径を、画像解析や切断法にて測定し、各オーステナイト粒径を平均して平均オーステナイト粒径を得る。
T1=850+10×([C]+[N])×[Mn]+350×[Nb]+250×[Ti]+40×[B]+10×[Cr]+100×[Mo]+100×[V] (式7)
なお、この式7では、[C]、[N]、[Mn]、[Nb]、[Ti]、[B]、[Cr]、[Mo]及び[V]は、それぞれ、C、N、Mn、Nb、Ti、B、Cr、Mo及びV量の質量百分率である。また、式7中に含まれない化学元素(化学成分)の量は、0%として計算する。そのため、上記の基本成分のみを含む基本組成では、上記式7の代わりに、下記式8を使用してもよい。
T1=850+10×([C]+[N])×[Mn] (式8)
また、鋼が選択元素を含む場合には、式8により算出される温度の代わりに式7により算出される温度をT1(℃)とする必要がある。
仕上げ圧延では、上記式7または式8により得られる温度T1(℃)を基準に、T1+30℃以上かつT1+200℃以下の温度範囲(望ましくはT1+50℃かつT1+100℃以下の温度範囲)では、大きな圧下率を確保し、Ar3℃以上かつT1+30℃未満の温度範囲では、圧下率を小さな範囲(0%を含む)に制限する。上記の粗圧延に加え、このような仕上げ圧延を行うことにより、最終製品の局部変形能を高めることができる。
T1+30℃以上かつT1+200℃以下の温度範囲において大きな圧下率を確保し、Ar3℃以上かつT1+30℃未満の温度範囲において圧下率を制限することにより、5/8~3/8の板厚範囲である板厚中央部における{100}<011>~{223}<110>方位群の平均極密度と、{332}<113>の結晶方位の極密度とを十分に制御して最終製品の局部変形能が飛躍的に改善される。この温度T1自体は、経験的に求められている。温度T1を基準として、各鋼のオーステナイト域での再結晶が促進される温度範囲を決定できることを本発明者らは実験により経験的に知見した。さらに良好な局部変形能を得るためには、圧下により多くの量の歪を蓄積することが重要であるため、T1+30℃以上かつT1+200℃以下の温度範囲での累積圧下率は、50%以上である。さらには、この累積圧下率は、歪蓄積による再結晶促進の観点から70%以上であることが望ましい。また、累積圧下率の上限を制限することにより、圧延温度をより十分に確保し、圧延負荷をさらに抑制することができる。そのため、累積圧下率が、90%以下であってもよい。
また、Ar3℃以上かつT1+30℃未満の温度範囲での圧下率が大きいと、再結晶したオーステナイト粒が展伸し、局部変形能が劣化する。
すなわち、本実施形態に係る製造条件では、仕上げ圧延においてオーステナイトを均一かつ微細に再結晶させることで熱延製品の集合組織及びr値を制御して穴拡げ性や曲げ性といった局部変形能を改善することができる。
ここで、圧下率は、圧延荷重や板厚の測定などから実績または計算により求めることができる。また、圧延温度(例えば、上記各温度範囲)については、スタンド間温度計により実測したり、ラインスピードや圧下率などから加工発熱を考慮した計算シミュレーションにより計算したり、その両方(実測及び計算)を行ったりすることによって得ることができる。また、上記において、1パスでの圧下率は、圧延スタンド通過前の入口板厚に対する1パスでの圧下量(圧延スタンド通過前の入口板厚と圧延スタンド通過後の出口板厚との差)の百分率である。累積圧下率は、上記各温度範囲での圧延における最初のパス前の入口板厚を基準とし、この基準に対する累積圧下量(上記各温度範囲での圧延における最初のパス前の入口板厚と上記各温度範囲での圧延における最終パス後の出口板厚との差)の百分率である。さらに、Ar3温度は、以下の式9により求められる。
Ar3=879.4-516.1×[C]-65.7×[Mn]+38.0×[Si]+274.7×[P] (式9)
上記熱間圧延における大圧下パス(上述のように、大圧下パスは、T1+30℃以上かつT1+200℃以下の温度範囲における30%以上の圧下率の圧下(パス)である)のうちの最終パスの完了から一次冷却を開始するまでの待ち時間t(秒)が下記の式10を満たすように、大圧下パスのうちの最終パスに相当する圧延スタンド後に鋼を冷却する。ここで、式10中のt1は、下記式11により求めることができる。式11中のTfは、大圧下パスの最終パス完了時の鋼板の温度(℃)であり、P1は、大圧下パスのうちの最終パスでの圧下率(%)である。ここで、操業性(例えば、形状矯正や二次冷却の制御性)を考慮する場合には、一次冷却を圧延スタンド間で行うとよい。
待ち時間tが、式10の右辺の値(2.5×t1)を超えると、ほとんど再結晶が完了している一方で、結晶粒が著しく成長して結晶粒径が増加するため、r値及び伸びが低下する。そのため、待ち時間tは、2.5×t1秒以下である。
t≦2.5×t1 (式10)
t1=0.001×((Tf-T1)×P1/100)2-0.109×((Tf-T1)×P1/100)+3.1 (式11)
また、一次冷却における平均冷却速度が50℃/秒以上であることが望ましい。この一次冷却での平均冷却速度が50℃/秒以上であると、再結晶したオーステナイト粒の粒成長をより抑制することができる。一方、平均冷却速度の上限を特に定める必要はないが、板形状の観点から平均冷却速度が200℃/秒以下であってもよい。
以上のような製造方法によって、優れた局部変形能を有する熱延鋼板を得ることができる。
表1及び表2に示した化学組成(残部が鉄及び不可避的不純物)を有する鋼a~tを用いて検討した結果について説明する。これらの鋼を溶製及び鋳造後、そのままもしくは一旦室温まで冷却された鋼を再加熱し、900℃~1300℃の温度範囲に加熱し、その後、表3~6に示される製造条件で熱間圧延(Ar3以上の温度範囲のオーステナイト域)及び温度制御(冷却や保持等)を行い、2~5mm厚の熱延鋼板を得た。
局部変形能の指標として、最終製品の穴拡げ率λおよび90°V字曲げによる限界曲げ半径(d/RmC)を用いた。なお、引張り試験(TS及びELの測定)、曲げ試験及び穴拡げ試験は、それぞれ、JIS Z 2241、JIS Z 2248(Vブロック90°曲げ試験)及び鉄連規格JFS T1001に準拠した。また、前述のEBSDを用いて、板幅方向の1/4の位置における圧延方向に平行な板厚断面の5/8~3/8の領域の板厚中央部に対して0.5μmピッチで極密度を測定した。また、各方向のr値(rC、r30)については、JIS Z 2254(2008)(ISO10113(2006))に準拠し、前述した方法により測定した。
なお、表1~8の下線は、本発明の条件を満たさない条件を示している。また、製造No.38では、T1+30℃以上かつT1+200℃以下の温度範囲内における圧延が30%以上のパスを含まないため、P1の値として、T1+30℃以上かつT1+200℃以下の温度範囲の圧延における最終パスの圧下率を使用した。
一方、製造No.15~24及び35では、本発明の条件を満たさなかったため、得られた鋼板のd/RmC、TS×λ、TS×ELの少なくとも1つが十分ではなかった。
Claims (14)
- 鋼板の化学組成が、質量%で、
C:0.02%以上かつ0.5%以下、
Si:0.001%以上かつ4.0%以下、
Mn:0.001%以上かつ4.0%以下、
Al:0.001%以上かつ4.0%以下
を含有し、
P:0.15%以下、
S:0.03%以下、
N:0.01%以下、
O:0.01%以下
に制限し、残部が鉄および不可避的不純物からなり、
前記鋼板の化学組成では、Si量とAl量との合計が1.0%以上かつ4.0%以下であり、
5/8~3/8の板厚範囲である板厚中央部では、{100}<011>、{116}<110>、{114}<110>、{112}<110>、{223}<110>の各結晶方位の極密度の相加平均で表される極密度である{100}<011>~{223}<110>方位群の平均極密度が1.0以上かつ6.5以下であり、かつ、{332}<113>の結晶方位の極密度が1.0以上かつ5.0以下であり、
前記鋼板のミクロ組織に、複数の結晶粒が存在し、このミクロ組織が、面積率で、残留オーステナイトを2%以上かつ30%以下、フェライトを20%以上かつ50%以下、ベイナイトを10%以上かつ60%以下含み、前記ミクロ組織では、面積率で、パーライトが20%以下、マルテンサイトが20%以下に制限され、
圧延方向に対して直角方向のランクフォード値であるrCが0.70以上かつ1.10以下であり、かつ、前記圧延方向に対して30°をなす方向のランクフォード値であるr30が0.70以上かつ1.10以下である
ことを特徴とする熱延鋼板。 - 前記鋼板の化学組成では、更に、質量%で、
Ti:0.001%以上かつ0.2%以下、
Nb:0.001%以上かつ0.2%以下、
V:0.001%以上かつ1.0%以下、
W:0.001%以上かつ1.0%以下、
Cu:0.001%以上かつ2.0%以下、
B:0.0001%以上かつ0.005%以下、
Mo:0.001%以上かつ1.0%以下、
Cr:0.001%以上かつ2.0%以下、
As:0.0001%以上かつ0.50%以下、
Mg:0.0001%以上かつ0.010%以下、
REM:0.0001%以上かつ0.1%以下、
Ca:0.0001%以上かつ0.010%以下、
Ni:0.001%以上かつ2.0%以下、
Co:0.0001%以上かつ1.0%以下、
Sn:0.0001%以上かつ0.2%以下、
Zr:0.0001%以上かつ0.2%以下
から選択される1種以上を含有することを特徴とする請求項1に記載の熱延鋼板。 - 前記結晶粒の体積平均径が1μm以上かつ4μm以下であることを特徴とする請求項1または2に記載の熱延鋼板。
- 前記{100}<011>~{223}<110>方位群の平均極密度が1.0以上かつ5.0以下であり、前記{332}<113>の結晶方位の極密度が1.0以上かつ4.0以下であることを特徴とする請求項1または2に記載の熱延鋼板。
- 前記複数の結晶粒のうち、20μmを超える結晶粒の面積割合が10%以下に制限されていることを特徴とする請求項1または2に記載の熱延鋼板。
- 前記残留オーステナイト及び前記マルテンサイトのうち、少なくとも100個の結晶粒に対する互いにもっとも近い結晶粒間の距離LMAの標準偏差が5μm以下であることを特徴とする請求項1または2に記載の熱延鋼板。
- 質量%で、
C:0.02%以上かつ0.5%以下、
Si:0.001%以上かつ4.0%以下、
Mn:0.001%以上かつ4.0%以下、
Al:0.001%以上かつ4.0%以下
を含有し、
P:0.15%以下、
S:0.03%以下、
N:0.01%以下、
O:0.01%以下
に制限し、残部が鉄および不可避的不純物からなり、Si量とAl量との合計が1.0%以上かつ4.0%以下である化学組成を有する鋼に対して、1000℃以上かつ1200℃以下の温度範囲で、40%以上の圧下率のパスを少なくとも1回以上含む第1の熱間圧延を行い、前記鋼の平均オーステナイト粒径を200μm以下とし;
下記式1により算出される温度をT1℃とした場合、T1+30℃以上かつT1+200℃以下の温度範囲に30%以上の圧下率の大圧下パスを含み、T1+30℃以上かつT1+200℃以下の温度範囲での累積圧下率が50%以上であり、Ar3℃以上かつT1+30℃未満の温度範囲での累積圧下率が30%以下に制限され、圧延終了温度がAr3℃以上である第2の熱間圧延を前記鋼に対して行い;
前記大圧下パスのうちの最終パスの完了から冷却開始までの待ち時間t秒が式2を満たすように、前記鋼に対して一次冷却を行い;
630℃以上かつ800℃以下の範囲の温度T3まで10~100℃/秒の平均冷却速度で前記鋼を冷却し;
630℃以上かつ800℃以下の温度範囲内に1秒以上かつ20秒以下前記鋼を保持、もしくは、前記温度T3から前記温度T3未満かつ550℃以上の範囲内の温度まで20℃/秒以下の平均冷却速度で前記鋼を徐冷し;
350~500℃の温度範囲で前記鋼を巻き取り;
350~500℃の温度範囲内に前記鋼を30~300分保持する温度範囲制御を行った後、前記鋼を空冷する
ことを特徴とする熱延鋼板の製造方法。
T1=850+10×([C]+[N])×[Mn] (式1)
ここで、[C]、[N]及び[Mn]は、それぞれ、前記鋼中のC、N及びMn量の質量百分率である。
t≦2.5×t1 (式2)
ここで、t1は下記式3で表される。
t1=0.001×((Tf-T1)×P1/100)2-0.109×((Tf-T1)×P1/100)+3.1 (式3)
ここで、Tfは前記最終パス完了時の前記鋼の摂氏温度であり、P1は前記最終パスでの圧下率の百分率である。 - 前記鋼は、前記化学組成として、更に、質量%で、
Ti:0.001%以上かつ0.2%以下、
Nb:0.001%以上かつ0.2%以下、
V:0.001%以上かつ1.0%以下、
W:0.001%以上かつ1.0%以下、
Cu:0.001%以上かつ2.0%以下、
B:0.0001%以上かつ0.005%以下、
Mo:0.001%以上かつ1.0%以下、
Cr:0.001%以上かつ2.0%以下、
As:0.0001%以上かつ0.50%以下、
Mg:0.0001%以上かつ0.010%以下、
REM:0.0001%以上かつ0.1%以下、
Ca:0.0001%以上かつ0.010%以下、
Ni:0.001%以上かつ2.0%以下、
Co:0.0001%以上かつ1.0%以下、
Sn:0.0001%以上かつ0.2%以下、
Zr:0.0001%以上かつ0.2%以下
から選択される1種以上を含有し、前記式1により算出される温度の代わりに下記式4により算出される温度を前記T1とすることを特徴とする請求項7に記載の熱延鋼板の製造方法。
T1=850+10×([C]+[N])×[Mn]+350×[Nb]+250×[Ti]+40×[B]+10×[Cr]+100×[Mo]+100×[V] (式4)
ここで、[C]、[N]、[Mn]、[Nb]、[Ti]、[B]、[Cr]、[Mo]及び[V]は、それぞれ、前記鋼中のC、N、Mn、Nb、Ti、B、Cr、Mo及びV量の質量百分率である。 - 前記待ち時間t秒が、さらに前記t1を用いた下記式5を満たすことを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
t<t1 (式5) - 前記待ち時間t秒が、さらに前記t1を用いた下記式6を満たすことを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
t1≦t≦t1×2.5 (式6) - 前記一次冷却では、平均冷却速度が50℃/秒以上であり、冷却開始時の鋼温度と冷却終了時の鋼温度との差である冷却温度変化が40℃以上かつ140℃以下であり、前記冷却終了時の鋼温度がT1+100℃以下であることを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
- T1+30℃以上かつT1+200℃以下の温度範囲における圧延の最終パスが前記大圧下パスであることを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
- 前記温度範囲制御では、温度変化速度が-40℃/h以上かつ40℃/h以下であることを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
- 前記一次冷却を圧延スタンド間で行うことを特徴とする請求項7または8に記載の熱延鋼板の製造方法。
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CN109881093B (zh) * | 2019-03-01 | 2020-11-13 | 北京科技大学 | 一种热气胀成型用空冷强化钢及其制备方法 |
CN113286910B (zh) | 2019-03-29 | 2023-03-17 | 日本制铁株式会社 | 钢板及其制造方法 |
JP7239009B2 (ja) * | 2019-10-01 | 2023-03-14 | 日本製鉄株式会社 | 熱延鋼板 |
CN110777297B (zh) * | 2019-10-12 | 2022-07-05 | 河钢股份有限公司 | 一种高扩孔性高拉延性高强度钢板及其制造方法 |
US20230287531A1 (en) * | 2020-07-20 | 2023-09-14 | Arcelormittal | Heat treated cold rolled steel sheet and a method of manufacturing thereof |
WO2022070840A1 (ja) * | 2020-09-30 | 2022-04-07 | 日本製鉄株式会社 | 高強度鋼板 |
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KR102469876B1 (ko) * | 2020-12-18 | 2022-11-23 | 주식회사 포스코 | 밀착성이 우수한 고강도 법랑용 냉연강판 및 이의 제조방법 |
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61217529A (ja) | 1985-03-22 | 1986-09-27 | Nippon Steel Corp | 延性のすぐれた高強度鋼板の製造方法 |
JPH0559429A (ja) | 1991-09-03 | 1993-03-09 | Nippon Steel Corp | 加工性に優れた高強度複合組織冷延鋼板の製造方法 |
JP2003113440A (ja) * | 2001-10-04 | 2003-04-18 | Nippon Steel Corp | 形状凍結性に優れる絞り可能な高強度薄鋼板およびその製造方法 |
JP2004250744A (ja) * | 2003-02-19 | 2004-09-09 | Nippon Steel Corp | 形状凍結性に優れた高加工性高強度熱延鋼板とその製造方法 |
JP2009114523A (ja) * | 2007-11-08 | 2009-05-28 | Nippon Steel Corp | 剛性、深絞り性及び穴拡げ性に優れた高強度冷延鋼板及びその製造方法 |
Family Cites Families (42)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000119804A (ja) | 1998-10-16 | 2000-04-25 | Nippon Steel Corp | 深絞り性に優れる熱延鋼板およびその製造方法 |
JP2000144314A (ja) | 1998-11-02 | 2000-05-26 | Nippon Steel Corp | 角筒絞り性に優れる熱延鋼板およびその製造方法 |
JP3539548B2 (ja) | 1999-09-20 | 2004-07-07 | Jfeスチール株式会社 | 加工用高張力熱延鋼板の製造方法 |
US6589369B2 (en) * | 2000-04-21 | 2003-07-08 | Nippon Steel Corporation | High fatigue strength steel sheet excellent in burring workability and method for producing the same |
JP3990553B2 (ja) | 2000-08-03 | 2007-10-17 | 新日本製鐵株式会社 | 形状凍結性に優れた高伸びフランジ性鋼板およびその製造方法 |
JP3814134B2 (ja) | 2000-09-21 | 2006-08-23 | 新日本製鐵株式会社 | 加工時の形状凍結性と衝撃エネルギー吸収能に優れた高加工性高強度冷延鋼板とその製造方法 |
KR100543956B1 (ko) | 2000-09-21 | 2006-01-23 | 신닛뽄세이테쯔 카부시키카이샤 | 형상 동결성이 우수한 강판 및 그 제조방법 |
AUPR047900A0 (en) | 2000-09-29 | 2000-10-26 | Bhp Steel (Jla) Pty Limited | A method of producing steel |
JP3927384B2 (ja) * | 2001-02-23 | 2007-06-06 | 新日本製鐵株式会社 | 切り欠き疲労強度に優れる自動車用薄鋼板およびその製造方法 |
JP4028719B2 (ja) | 2001-11-26 | 2007-12-26 | 新日本製鐵株式会社 | 形状凍結性に優れる絞り可能なバーリング性高強度薄鋼板およびその製造方法 |
CN100347325C (zh) * | 2001-10-04 | 2007-11-07 | 新日本制铁株式会社 | 可拉延并具有优异定型性能的高强度薄钢板及其生产方法 |
FR2836930B1 (fr) | 2002-03-11 | 2005-02-25 | Usinor | Acier lamine a chaud a tres haute resistance et de faible densite |
JP3821036B2 (ja) * | 2002-04-01 | 2006-09-13 | 住友金属工業株式会社 | 熱延鋼板並びに熱延鋼板及び冷延鋼板の製造方法 |
JP3901039B2 (ja) | 2002-06-28 | 2007-04-04 | Jfeスチール株式会社 | 成形性に優れる超高強度冷延鋼板およびその製造方法 |
JP4160839B2 (ja) | 2003-02-19 | 2008-10-08 | 新日本製鐵株式会社 | 形状凍結性に優れた異方性の小さな高加工性高強度熱延鋼板とその製造方法 |
JP4235030B2 (ja) | 2003-05-21 | 2009-03-04 | 新日本製鐵株式会社 | 局部成形性に優れ溶接部の硬さ上昇を抑制した引張強さが780MPa以上の高強度冷延鋼板および高強度表面処理鋼板 |
TWI248977B (en) * | 2003-06-26 | 2006-02-11 | Nippon Steel Corp | High-strength hot-rolled steel sheet excellent in shape fixability and method of producing the same |
JP4384523B2 (ja) | 2004-03-09 | 2009-12-16 | 新日本製鐵株式会社 | 形状凍結性に極めて優れた低降伏比型高強度冷延鋼板およびその製造方法 |
JP4692015B2 (ja) | 2004-03-30 | 2011-06-01 | Jfeスチール株式会社 | 伸びフランジ性と疲労特性に優れた高延性熱延鋼板およびその製造方法 |
JP4464748B2 (ja) | 2004-07-06 | 2010-05-19 | 新日本製鐵株式会社 | 形状凍結性と伸びフランジ成形性に優れた高強度鋼板、高強度溶融亜鉛めっき鋼板、および、高強度合金化溶融亜鉛めっき鋼板とそれらの製造方法 |
CN102251087B (zh) | 2005-08-03 | 2013-03-27 | 住友金属工业株式会社 | 热轧钢板及冷轧钢板及它们的制造方法 |
EP1767659A1 (fr) | 2005-09-21 | 2007-03-28 | ARCELOR France | Procédé de fabrication d'une pièce en acier de microstructure multi-phasée |
JP5058508B2 (ja) | 2005-11-01 | 2012-10-24 | 新日本製鐵株式会社 | 低降伏比型高ヤング率鋼板、溶融亜鉛めっき鋼板、合金化溶融亜鉛めっき鋼板及び鋼管、並びにそれらの製造方法 |
JP4714574B2 (ja) | 2005-12-14 | 2011-06-29 | 新日本製鐵株式会社 | 高強度鋼板及びその製造方法 |
JP2007291514A (ja) | 2006-03-28 | 2007-11-08 | Jfe Steel Kk | 冷延−再結晶焼鈍後の面内異方性が小さい熱延鋼板、面内異方性が小さい冷延鋼板およびそれらの製造方法 |
JP5228447B2 (ja) | 2006-11-07 | 2013-07-03 | 新日鐵住金株式会社 | 高ヤング率鋼板及びその製造方法 |
JP5214905B2 (ja) * | 2007-04-17 | 2013-06-19 | 株式会社中山製鋼所 | 高強度熱延鋼板およびその製造方法 |
JP5053157B2 (ja) * | 2007-07-04 | 2012-10-17 | 新日本製鐵株式会社 | プレス成形性の良好な高強度高ヤング率鋼板、溶融亜鉛めっき鋼板、合金化溶融亜鉛めっき鋼板及び鋼管、並びに、それらの製造方法 |
JP5088021B2 (ja) | 2007-07-05 | 2012-12-05 | 新日本製鐵株式会社 | 高剛性高強度冷延鋼板及びその製造方法 |
JP2009097545A (ja) | 2007-10-13 | 2009-05-07 | Toyota Motor Corp | 車両用電子制御カップリング |
JP5217395B2 (ja) * | 2007-11-30 | 2013-06-19 | Jfeスチール株式会社 | 伸びの面内異方性が小さい高強度冷延鋼板およびその製造方法 |
JP4894863B2 (ja) * | 2008-02-08 | 2012-03-14 | Jfeスチール株式会社 | 加工性に優れた高強度溶融亜鉛めっき鋼板およびその製造方法 |
MX2010010989A (es) * | 2008-04-10 | 2010-12-21 | Nippon Steel Corp | Chapas de acero de alta resistencia que son excelentes en el equilibrio entre facilidad de trabajo en la desbastacion de metales y ductilidad, y excelentes en resistencia a la fatiga, chapas de acero recubiertas de zinc y procesos para la produccion |
JP5068689B2 (ja) | 2008-04-24 | 2012-11-07 | 新日本製鐵株式会社 | 穴広げ性に優れた熱延鋼板 |
KR20100010169A (ko) | 2008-07-22 | 2010-02-01 | 박은정 | 다층인쇄회로기판 및 그 제조방법 |
JP5245647B2 (ja) | 2008-08-27 | 2013-07-24 | Jfeスチール株式会社 | プレス成形性と磁気特性に優れた熱延鋼板およびその製造方法 |
JP5206244B2 (ja) * | 2008-09-02 | 2013-06-12 | 新日鐵住金株式会社 | 冷延鋼板 |
JP5370016B2 (ja) | 2008-09-11 | 2013-12-18 | 新日鐵住金株式会社 | 穴広げ性に優れた高強度熱延鋼板及びその製造方法 |
JP4737319B2 (ja) | 2009-06-17 | 2011-07-27 | Jfeスチール株式会社 | 加工性および耐疲労特性に優れた高強度合金化溶融亜鉛めっき鋼板およびその製造方法 |
WO2011148490A1 (ja) | 2010-05-27 | 2011-12-01 | 住友金属工業株式会社 | 鋼板およびその製造方法 |
JP5163835B2 (ja) | 2010-07-28 | 2013-03-13 | 新日鐵住金株式会社 | 熱延鋼板、冷延鋼板、亜鉛めっき鋼板およびこれらの製造方法 |
CN103459647B (zh) | 2011-03-28 | 2015-09-02 | 新日铁住金株式会社 | 热轧钢板及其制造方法 |
-
2012
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61217529A (ja) | 1985-03-22 | 1986-09-27 | Nippon Steel Corp | 延性のすぐれた高強度鋼板の製造方法 |
JPH0559429A (ja) | 1991-09-03 | 1993-03-09 | Nippon Steel Corp | 加工性に優れた高強度複合組織冷延鋼板の製造方法 |
JP2003113440A (ja) * | 2001-10-04 | 2003-04-18 | Nippon Steel Corp | 形状凍結性に優れる絞り可能な高強度薄鋼板およびその製造方法 |
JP2004250744A (ja) * | 2003-02-19 | 2004-09-09 | Nippon Steel Corp | 形状凍結性に優れた高加工性高強度熱延鋼板とその製造方法 |
JP2009114523A (ja) * | 2007-11-08 | 2009-05-28 | Nippon Steel Corp | 剛性、深絞り性及び穴拡げ性に優れた高強度冷延鋼板及びその製造方法 |
Non-Patent Citations (3)
Title |
---|
K. SUGIMOTO ET AL., ISIJ INTERNATIONAL, vol. 40, 2000, pages 920 |
KATO ET AL., IRON-MAKING RESEARCH, vol. 312, 1984, pages 41 |
TAKAHASHI ET AL., NIPPON STEEL TECHNICAL REPORT, no. 378, 2003, pages 7 |
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