JP2009013478A - High-rigidity and high-strength cold-rolled steel sheet and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled steel sheet having high Young's modulus in a rolling direction, and to provide a manufacturing method therefor. <P>SOLUTION: The high-rigidity and high-strength cold-rolled steel sheet includes C, Si, Mn, P, S, Al, N, and further one or both elements of 0.005 to 0.100% Nb and 0.002 to 0.150% Ti in total of 0.01 to 0.25%, while satisfying the expressions: 3.0≤3.6Mn+9.6Mo+4.7W+6.2Ni+18.6Cu+0.7Cr≤7.5 (expression 2) and 450≤Bs[°C]≤700, wherein Bs=830-270C-90Mn-37Ni-70Cr-83Mo (expression 1); wherein at a position of 3/8 of the plate thickness, a mean value (A) of random X-ray intensity ratios of crystals having orientations of ä100}<011>, ä211}<011> and ä111}<011> is 3.0 or more and a mean value (B) of random X-ray intensity ratios of crystals having orientations of ä554}<225> and ä110}<001> is of 5.0 or less, while (A)/(B) satisfies the expression of (A)/(B)≥1.5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-rigidity and high-strength cold-rolled steel plate and a method for producing the same.

  So far, many proposals have been made on steel sheets that control the texture of the steel sheets and increase the Young's modulus only in the direction perpendicular to the rolling direction (referred to as the width direction) (for example, Patent Documents 1 to 4). ). These are cold-rolled steel plates having a higher Young's modulus in the direction perpendicular to the rolling direction, and do not propose a technique for increasing the Young's modulus in the rolling direction.

  In addition, a steel plate manufacturing method in which the Young's modulus in the rolling direction and the width direction is increased at the same time, in addition to rolling in a certain direction, rolling in a direction perpendicular thereto is proposed (for example, Patent Document 5). However, in the continuous hot rolling process for thin steel sheets, if the rolling direction is changed in the middle, the productivity is remarkably hindered, which is not realistic.

  The width of the thin steel plate is about 2 m at the maximum, and in order to apply the high Young's modulus steel plate to a long member exceeding this, it was necessary to increase the Young's modulus in the rolling direction. Moreover, the fact that a high Young's modulus can be obtained in both the rolling direction and the width direction dramatically increases the degree of freedom in designing the member.

  Some of the present inventors have proposed a method of applying shear strain to the surface layer portion of the steel sheet and increasing the Young's modulus in the rolling direction of the surface layer portion (for example, Patent Documents 6 and 7). These are developed from a texture that increases the Young's modulus in the rolling direction in the surface layer portion of the steel sheet, and the Young's modulus measured by the vibration method is a high value exceeding 230 GPa. This is because when the Young's modulus of the surface layer portion is high, the contribution of the surface layer portion having a large bending moment increases in the vibration method measured by bending deformation.

  The vibration method, which is one of the Young's modulus measurement methods, is a measurement method in which bending deformation is applied to the steel sheet while changing the frequency to determine the frequency at which resonance occurs, and this is converted into Young's modulus. The Young's modulus measured by such a method is also called dynamic Young's modulus, and is the Young's modulus obtained at the time of bending deformation.

  However, for example, stress acting on a building material such as a long beam or a column or a structural member for an automobile is not bending but mainly tensile stress and compressive stress. Therefore, when applying to such a member, not the dynamic Young's modulus obtained by the vibration method, but the Young's modulus is obtained from the slope in the elastic deformation region of the stress-strain curve obtained when the tensile test is performed. It is extremely important to increase the Young's modulus in the static tension method, that is, the static Young's modulus. The Young's modulus measured by the static tension method is the Young's modulus of the entire material determined only by the ratio of the thickness of the layer having a high Young's modulus and the layer having a low Young's thickness, regardless of the site in the thickness direction.

  However, in the methods proposed in Patent Documents 6 and 7, the texture at the center of the plate thickness does not necessarily contribute to the improvement of the Young's modulus in the rolling direction. Therefore, although the Young's modulus measured by the vibration method is high, the Young's modulus measured by the static tension method is not necessarily high. Furthermore, since cold-rolled steel sheets are cold-rolled and annealed after hot rolling, it is difficult to maintain the texture formed on the surface layer of the hot-rolled steel sheet as it is, and a high Young's modulus is obtained by the static tension method. It is very difficult to get.

JP 2006-152362 A JP 2006-183130 A JP 2006-183131 A JP 2005-314792 A JP-A-4-147717 JP-A-2005-273001 Japanese Patent Application No. 2005-330429

  The present invention provides a cold-rolled steel sheet having a high static Young's modulus in the rolling direction and a method for producing the same.

  The present invention suppresses recrystallization by adding Nb and / or Ti, and further adjusts the addition amount of C, Mn, Mo, W, Ni, Cu, and Cr to appropriate conditions, A cold-rolled steel sheet and a manufacturing method in which shear strain is introduced to a deep part, bainite is generated in the structure after hot rolling, and a texture is formed that increases the static Young's modulus in the rolling direction after cold rolling and annealing. Yes, the summary is as follows.

(1) By mass%, C: 0.010 to 0.200%, Mn: 0.10 to 2.50%, Si: 2.50% or less, P: 0.150% or less, S: It is limited to 0.0150% or less, Al: 0.150% or less, N: 0.0100% or less, and Nb: 0.005 to 0.100%, Ti: 0.002 to 0.150% Alternatively, both are contained in a total of 0.01 to 0.25%, the balance is made of Fe and inevitable impurities, Bs [° C.] in the following (Formula 1) is in the range of 450 to 700 ° C., and the plate thickness is 3 The average value (A) of the X-ray random intensity ratio of {100} <011>, {211} <011>, {111} <011> orientation at the / 8 position is 3.0 or more, {554} <225> , {110} <001> orientation X-ray random intensity ratio average value (B) is 5.0 or less, and (A) / ( ) High rigidity and high strength cold rolled steel sheet, which is a ≧ 1.5.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
Here, C, Mn, Ni, Cr, and Mo are content [mass%] of each element.

(2) By mass%, Mo: 0.005 to 0.500%, Cr: 0.005 to 1.000%, W: 0.005 to 1.500%, Cu: 0.005 to 0.350% Ni: 0.005 to 0.350% of one kind or two or more kinds are contained in a range satisfying the following (formula 2), and the high rigidity and high strength cold-rolled steel according to the above (1)鈑.
3.0 ≦ 3.2Mn + 9.6Mo + 4.7W + 6.2Ni + 18.6Cu + 0.7Cr ≦ 7.5 (Formula 2)
Here, Mn, Mo, W, Ni, Cu, and Cr are the content [% by mass] of each element.
(3) The high-rigidity and high-strength cold-rolled steel sheet according to (1) or (2) above, which contains B: 0.0003 to 0.0100% by mass% (4) , Ca: 0.0005 to 0.1000%, Rem: 0.0005 to 0.1000%, V: 0.001 to 0.100%, or one or more of the above (characterized above) The high-rigidity and high-strength cold-rolled steel plate according to any one of 1) to (3).
(5) The X-ray random intensity ratio of one or both of the {110} <112> orientation and the {110} <111> orientation at a plate thickness of 1/16 is 3 or more. The high-rigidity high-strength cold-rolled steel plate according to any one of to (4).
(6) The high-rigidity and high-strength cold-rolled steel plate according to any one of (1) to (5) above, wherein the static Young's modulus in the rolling direction is 215 GPa or more.

(7) A high-rigidity, high-strength hot-dip galvanized cold-rolled steel sheet, wherein the high-rigidity, high-strength cold-rolled steel sheet according to any one of (1) to (6) is hot-dip galvanized. .
(8) High-rigidity and high-strength alloyed hot-dip galvanized steel, characterized in that alloyed hot-dip galvanizing is applied to the high-rigidity and high-strength cold-rolled steel sheet according to any one of (1) to (6) above Plated cold-rolled steel sheet.

(9) A method for producing a cold-rolled steel plate according to any one of (1) to (6) above, wherein a steel piece having the chemical component according to any one of (1) to (4) is 1100. The total reduction ratio at 1000 ° C. or less is 40% or more, the average value of the shape ratio X obtained by the following (Formula 3) is 2.5 or more, and the temperature of the final pass is Ar ₃ Hot rolling is performed at a transformation point or higher and 900 ° C. or lower, and after winding within a temperature range of 450 to 650 ° C. below Bs [° C.] of (Formula 1), cold rolling of 30 to 80% is performed. High-rigidity and high-strength cooling, which is further performed by annealing at an average heating rate of 3 to 300 ° C./s from room temperature to 650 ° C. and heating to 650 ° C. to Ac ₃ transformation temperature and holding for 1 second or more. A method for producing rolled steel sheets.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
Shape ratio X = l _d / h _m (Formula 3)
l _d (contact arc length of hot-rolled roll and steel plate): √ (L × (h _in −h _out ) / 2),
h _m : (h _in + h _out ) / 2
L: roll diameter,
h _in : plate thickness on the rolling roll entry side,
h _out : thickness of the roll exit side,
Here, C, Mn, Ni, Cr, and Mo are content [mass%] of each element.
(10) The high-rigidity and high-strength cold-rolled steel sheet according to (9), wherein when performing the hot rolling, at least one pass of different peripheral speed rolling with a different peripheral speed ratio of 1% or more is performed. Manufacturing method.

(11) The method for producing a hot-dip galvanized cold-rolled steel sheet according to (7) above, wherein hot-dip galvanizing is performed on the surface of the steel sheet produced by the method according to (9) or (10). A method for producing a high-rigidity, high-strength hot-dip galvanized cold-rolled steel sheet.
(12) A method for producing a galvannealed cold-rolled steel sheet according to (8) above, wherein the surface of the steel sheet produced by the method according to (9) or (10) is hot dip galvanized. Then, the manufacturing method of the high-rigidity high-strength galvannealed cold-rolled steel sheet characterized by performing heat processing for 10 s or more in the temperature range to 450-600 degreeC.

  According to the present invention, a cold rolled steel sheet having a high Young's modulus with an improved static Young's modulus in the rolling direction can be obtained.

The Young's modulus depends on the crystal orientation, and the <111> direction has the effect of increasing the Young's modulus the most, and then the effect of increasing the Young's modulus is the <110> direction. On the other hand, when the <100> direction is accumulated, the Young's modulus is significantly reduced.
Therefore, increasing the orientation in which the <111> directions are aligned in the rolling direction (referred to as the <111> orientation group) in the steel sheet is most effective for increasing the Young's modulus.

The present inventors have proposed a method of increasing the dynamic Young's modulus in the rolling direction by utilizing the <111> orientation group that develops in the shear layer that develops in the surface layer portion of the hot-rolled sheet. However,
1) These surface orientations break to some extent during the subsequent cold rolling and annealing.
2) During cold rolling and annealing, an orientation that lowers the Young's modulus in the rolling direction develops at the center of the plate thickness.
For this reason, it has been difficult to increase the static Young's modulus in the rolling direction in cold-rolled steel sheets.

  Therefore, the present inventors pay attention to the texture at the center of the thickness after cold rolling annealing, and increase the <110> orientation group having the effect of increasing the Young's modulus next to the <111> orientation group as much as possible at the center of the thickness. In addition, intensive research was conducted on methods for reducing the <100> orientation. As a result, the following knowledge was newly obtained.

(I) When hot rolling is performed while suppressing recrystallization in the austenite phase (hereinafter referred to as γ phase) by adding Nb and / or Ti, the rolling direction is oriented in the <110> direction {100} <011 > To {111} <011> orientation groups develop. In order to suppress recrystallization during hot rolling, it is preferable to further add B.

(Ii) In order to further develop the developed {100} <011> to {111} <011> orientation groups during cold rolling, it is important to bainite the hot rolled sheet structure.

(Iii) However, if the {100} <011> to {111} <011> orientation group develops during hot rolling, the Young's modulus in the rolling direction is lowered after cold rolling annealing {554} <225> to { The {332} <113> orientation, which is the origin of the 110} <001> orientation group, also develops in the center of the thickness of the hot-rolled steel sheet. In order to suppress this, it is necessary to optimize the components such as Mn, Cr, and Mo in consideration of the stacking fault energy of the γ phase.

(Iv) Moreover, in order to suppress the development of {554} <225> to {110} <001> orientation groups during cold rolling / annealing, it is necessary to apply a shearing force to the inner layer as much as possible during hot rolling. It is. As described above, the shearing force acts to develop a shear texture (<111> orientation group) on the surface layer of the hot-rolled sheet and to significantly develop the Young's modulus in the rolling direction. However, it was revealed that when this shearing force was applied to the inner layer as much as possible, the texture also changed in the center of the plate thickness after cold rolling annealing. Although the cause of this is not clear, the texture and strain state of the hot-rolled sheet structure near the center of the sheet thickness change due to the shearing force acting to the inner layer, and during cold rolling / annealing, {554} <225>- It is considered that there is an effect of suppressing the development of the {110} <001> orientation. In order to apply the shearing force to the inner layer, it is very effective to control the shape ratio defined by the relationship between the rolling roll diameter and the plate thickness.

  About said (i), it is necessary to contain one or both of Nb: 0.005-0.100%, Ti: 0.002-0.150% in total 0.01-0.25% . Furthermore, it is preferable to contain B: 0.0003 to 0.001%.

About said (ii), content [mass%] of C, Mn, Ni, Cr, and Mo is set so that Bs [° C.] represented by the following (formula 1) falls within the range of 450 to 700 ° C. It is necessary to adjust.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
In the above (Formula 1), when the selective elements Ni, Cr, and Mo are impurities, that is, when the addition amount of each element is less than the preferred lower limit, it is calculated as 0.

  Bs [° C.] in (Expression 1) is an empirical expression that quantifies the influence of the component elements on the temperature related to the bainite of the hot-rolled sheet structure. In order to develop a texture during cold rolling, it is important that the hot rolled sheet structure has a bainite phase as the main phase. In a hot-rolled sheet in which two phases with different hardness such as ferrite phase + martensite phase and ferrite phase + pearlite phase are mixed, non-uniform deformation occurs around the hard phase during cold rolling, and the texture becomes random. End up.

  If Bs [° C.] of (Formula 1) exceeds 700 ° C., it becomes difficult to generate a bainite phase in the coiling temperature range, so this value was made the upper limit. Further, in order to make the hot-rolled sheet structure into a bainite main phase in the normal hot-rolling condition range, when the value of Bs [° C.] is less than 450 ° C., the hot-rolled sheet becomes hard and cold-rolled during cold rolling. Since this imposes a heavy burden on the apparatus and inhibits the development of texture, this value is set as the lower limit.

  Furthermore, it is necessary to set the upper limit of the coiling temperature after hot rolling to Bs [° C.] or less obtained in (Equation 1) and 650 ° C. or less. This is because when the coiling temperature exceeds Bs [° C.] or above 650 ° C., the hot-rolled sheet structure does not become the bainite main phase, and the texture is randomized during cold rolling and annealing. Moreover, about the minimum of coiling temperature, when it makes less than 450 degreeC, a hot-rolled board will become hard and the burden to a cold-rolling apparatus will become large at the time of cold rolling.

As for (iii), specifically, it is desirable to add Mn, Mo, W, Ni, Cu, and Cr so as to satisfy the following (Formula 2).
3.0 ≦ 3.2Mn + 9.6Mo + 4.7W + 6.2Ni + 18.6Cu + 0.7Cr
≦ 7.5 (Formula 2)
Here, Mn, Mo, W, Ni, Cu, and Cr are the contents [mass%] of each element, and when the selective elements Mo, W, Ni, Cu, and Cr are impurities, that is, each element. When the amount of addition is less than the preferred lower limit, it is calculated as 0.

  The above relational expression (Formula 2) is further examined by the present inventors based on a numerical expression of the effect of each element on the stacking fault energy of austenitic stainless steel having a γ phase. In addition, it has been modified. If the value of the relational expression of (Expression 2) exceeds 7.5, {332} <113> that develops an orientation that lowers the Young's modulus in the rolling direction after cold rolling annealing is developed at the center of the sheet thickness. Therefore, this value is the upper limit. From this point of view, it is more desirable to make it 6.5 or less. On the other hand, if the value of this relational expression is less than 3.0, it is difficult to ensure the strength of the material. Further, the degree of accumulation in the {110} <111> orientation, which increases the rolling direction Young's modulus in the surface layer, may decrease, and as a result, the rolling direction Young's modulus may decrease.

For (iv) above, the average value of the shape ratio for each pass of hot rolling performed at 1100 ° C. or lower needs to satisfy 2.5 or more in order to cause the hot rolling shear force to act on the inner layer. . As shown in the following (formula 3), the shape ratio X is a ratio between the contact arc tension of the roll and the steel plate and the average plate thickness. According to the knowledge obtained by the present inventors, the larger the value of the shape ratio X, the greater the shear force acts on the deeper portion in the thickness direction of the hot-rolled sheet, and the texture and strain state change. is there.
Shape ratio X = l _d / h _m (Formula 3)
Here, l _d (contact arc length of rolling roll and steel plate): √ (L × (h _in −h _out ) / 2)
h _m : (h _in + h _out ) / 2
L: Diameter of the rolling roll
h _in : Thickness on the entry side of the rolling roll
h _out : Plate thickness on the exit side of the rolling roll

  If the average value of the shape ratio X obtained by the above (Formula 3) is less than 2.5, a high Young's modulus in the rolling direction cannot be obtained after cold rolling annealing. In order to obtain a high Young's modulus in the rolling direction, the average value of the shape ratio X is preferably as large as possible, and a more preferable lower limit value is 3.5, more desirably 5.0 or more. An upper limit is not particularly provided, but setting the average shape ratio to 10.0 or more in a normal hot rolling facility has a very large facility load.

  Hereinafter, the X-ray random strength ratio and Young's modulus of the cold-rolled steel sheet of the present invention will be described.

Average value (A) of X-ray random intensity ratio of {100} <011>, {211} <011>, {111} <011> orientation at the plate thickness 3/8 position:
These orientations are all effective for increasing the Young's modulus in the rolling direction. If the average value (A) of the X-ray random intensity ratios in these directions is less than 3.0, the Young's modulus in the rolling direction is not improved. Therefore, the lower limit of the value of (A) is set to 3.0. From this viewpoint, the value of (A) is preferably 5.0 or more, and more preferably 10.0 or more. Since the Young's modulus increases as this value increases, the upper limit is not particularly specified, but it is substantially difficult to set it to 30.0 or more.

  In order to set the value of (A) to 3.0 or more, as described in (i) above, addition of Nb and Ti is necessary, and addition of B is more preferable. Moreover, as described in (ii) above, in order to bainite the structure of the hot-rolled sheet, it is necessary to set the component composition and the winding temperature to appropriate conditions.

Average value (B) of X-ray random intensity ratios in {554} <225>, {110} <001> orientation at the plate thickness 3/8 position:
These orientations are all orientations that lower the Young's modulus in the rolling direction. Therefore, the average value (B) of these values must be 5.0 or less. Desirably 3 or less. Although the lower limit is not particularly set, in principle, this value cannot be smaller than 0.

  The {554} <225> and {110} <001> orientations are representative crystal orientations of the {554} <225> to {110} <001> orientation groups, and the value of (B) is 5.0 or less. In order to achieve this, as described in (iii) and (iv) above, it is necessary to control the component composition and the shape ratio. Furthermore, as described later, the cold rolling rate needs to be 80% or less, and is preferably 65% or less.

(A) / (B):
Average value (A) of {100} <011>, {211} <011>, {111} <011> orientation X-ray random intensity ratio (A) {554} <225>, {110 } The ratio (A) / (B) of the average value (B) of the X-ray random intensity ratio in the <001> orientation is 1.5 or more. If this range cannot be satisfied, the value of Young's modulus in the rolling direction will not increase. From this viewpoint, it is preferably 2.0 or more, and more preferably 3.0 or more.

X-ray random intensity ratio of one or both of {110} <112> orientation and {110} <111> orientation at a plate thickness of 1/16 position:
These orientations are all effective for increasing the Young's modulus in the rolling direction, particularly the dynamic Young's modulus. Therefore, the X-ray random intensity ratio is desirably 3.0 or more. From this point of view, it is preferably 5 or more. More desirably, it is 10.0 or more. In order to do this, it is preferable that the rolling reduction of the cold rolling is 55% or less as will be described later.

  {100} <011> orientation, {211} <011> orientation, {111} <011> orientation, {554} <225> orientation, {110} <001> orientation, {110} <112> orientation, And the {110} <111> orientation X-ray random intensity ratio is a series based on a plurality of pole figures among {110}, {100}, {211}, {310} pole figures measured by X-ray diffraction. What is necessary is just to obtain | require from the crystal orientation distribution function (Orientation Distribution Function, ODF) showing the three-dimensional texture calculated by the expansion | deployment method. Note that the X-ray random intensity ratio means that the X-ray intensity of a standard sample that does not accumulate in a specific orientation and the test material is measured under the same conditions by the X-ray diffraction method or the like. It is a numerical value obtained by dividing the line intensity by the X-ray intensity of the standard sample.

FIG. 1 shows an ODF of a φ ₂ = 45 ° cross section where the crystal orientation of the present invention is displayed. Here, the orientation of the crystal 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} and <uvw> are generic terms for equivalent planes, and [hkl] and (uvw) indicate individual crystal planes. That is, in the present invention, b. c. c. Since the structure is targeted, for example, (111), (−111), (1-11), (11-1), (−1-11), (-11-1), (1-1-1) , (-1-1-1) planes are equivalent and indistinguishable. In such a case, these orientations are collectively referred to as {111}.

In addition, since ODF is also used for the orientation display of a crystal structure with low symmetry, it is generally expressed by φ ₁ = 0 to 360 °, Φ = 0 to 180 °, φ ₂ = 0 to 360 °, Individual orientations are displayed in [hkl] (uvw). However, according to the invention, since the high body-centered cubic symmetry of interest, for Φ and phi ₂ is expressed in a range of 0 to 90 °.
In addition, the range of φ ₁ varies depending on whether or not symmetry due to deformation is taken into account when performing the calculation. In the present invention, φ ₁ is expressed as 0 to 90 ° in consideration of symmetry, that is, A method of selecting an average value in the same direction at φ ₁ = 0 to 360 ° on an ODF of 0 to 90 ° is selected. In this case, [hkl] (uvw) and {hkl} <uvw> are synonymous. Therefore, for example, the X-ray random intensity ratio of (110) [1-11] of the ODF in the φ2 = 45 ° cross section shown in FIG. 1 is the X-ray random intensity ratio in the {110} <111> orientation.

The sample for X-ray diffraction is manufactured as follows.
A steel plate is polished to a predetermined position in the plate thickness direction by mechanical polishing or chemical polishing, and finished to a mirror surface by buff polishing, and then strain is removed by electrolytic polishing or chemical polishing, and at the same time, 3/8 or 1/16 plate thickness Adjust so that the part becomes the measurement surface. Since it is difficult to accurately set the measurement surface to the predetermined plate thickness position, if the sample is prepared so that the measurement surface is within a range of 3% of the plate thickness with the target position as the center. Good. Further, when it is difficult to measure due to X-ray diffraction, even if the statistical measure sufficient number of the EBSP (E lectron B ack S cattering P attern) method or ECP (E lectron C hanneling P attern ) Method good.

  The measurement of the static Young's modulus is performed by applying a tensile stress corresponding to 1/2 of the yield strength of the steel sheet using a tensile specimen according to JIS Z 2201. That is, the Young's modulus is calculated based on the slope of the obtained stress-strain diagram by applying a tensile stress corresponding to ½ of the yield strength. In order to eliminate variation in measurement, the same test piece was used, and the value calculated as the average value of the three measured values excluding the maximum and minimum values was obtained as the Young's modulus. To do.

  Hereinafter, the reason for limiting the steel composition in the present invention will be further described. In addition,% of element content means the mass%.

C is an element that increases the strength, and from the viewpoint of Young's modulus, addition of 0.010% or more is necessary. This is because when the C content is reduced to less than 0.010%, the Ar ₃ transformation temperature rises, it becomes difficult to perform hot rolling at a low temperature, and the Young's modulus after cold rolling annealing may be reduced. Furthermore, in order to suppress the deterioration of the fatigue characteristics of the welded portion, it is preferably 0.020% or more.
On the other hand, if the C content exceeds 0.200%, the formability deteriorates, so the upper limit is made 0.200% or less. Moreover, since weldability may be impaired when the C content exceeds 0.100%, the upper limit of the C content is preferably 0.100% or less. Moreover, since the Young's modulus of a rolling direction may fall when C amount exceeds 0.060%, it is still more preferable to make an upper limit into 0.060% or less.

Si is a deoxidizing element, and the lower limit is not specified, but if it is less than 0.001%, the production cost becomes high. Si is an element that increases the strength by solid solution strengthening, and is also effective for obtaining a structure containing martensite, bainite, and retained austenite after cold rolling and annealing. Therefore, it may be positively added according to the target strength level, but if the added amount exceeds 2.50%, the press formability deteriorates, so 2.50% or less is made the upper limit.
Moreover, since chemical conversion processability will fall when there is much Si amount, it is preferable to set it as 1.20% or less. Furthermore, when hot dip galvanizing is performed, problems such as reduced plating adhesion and reduced productivity due to a delay in the alloying reaction may occur, so the upper limit of Si content should be 1.00% or less. Is preferred. From the viewpoint of Young's modulus, the upper limit of Si content is more preferably 0.60% or less, and still more preferably 0.30% or less.

Mn is an important element in the present invention. Mn is an element that lowers the Ar ₃ transformation point, which is a temperature at which the γ phase is transformed into the ferrite phase when heated to a high temperature during hot rolling, and by adding Mn, the γ phase becomes stable to a low temperature, The temperature of finish rolling can be lowered. In order to obtain this effect, it is necessary to add 0.10% or more of Mn. As will be described later, Mn has a correlation with the stacking fault energy in the γ phase, affects the formation of the work texture in the γ phase and the variant selection at the time of transformation, and the Young's modulus in the rolling direction after the transformation. It has the effect of developing a higher crystal orientation. From this viewpoint, it is preferable to add 1.00% or more of Mn. More preferably, 1.5% or more is added. On the other hand, when the amount of Mn added exceeds 2.50%, an orientation that lowers the Young's modulus in the rolling direction develops, so the upper limit is made 2.50% or less. Moreover, it is preferable to make an upper limit into 2.00% or less from the viewpoint of the same viewpoint and the adhesiveness of galvanization.

  P is an impurity, but may be positively added when the strength needs to be increased. P also has the effect of making the hot-rolled structure fine and improving workability. However, if the addition amount exceeds 0.150%, the fatigue strength after spot welding deteriorates, the yield strength increases, and a surface shape defect is caused during pressing. Furthermore, the alloying reaction becomes extremely slow during continuous hot dip galvanizing, and productivity is lowered. Also, the secondary workability is deteriorated. Therefore, the upper limit is set to 0.15%. From this point of view, the content is preferably 0.1% or less.

S is an impurity, and if it exceeds 0.0150%, it causes hot cracking or deteriorates workability, so this is the upper limit.
Al is a deoxidation preparation agent, and the lower limit is not particularly limited, but is preferably 0.010% or more from the viewpoint of deoxidation. On the other hand, Al significantly increases the transformation point, so if adding over 0.150%, it becomes difficult to perform γ region rolling at a low temperature, so the upper limit is made 0.150%.

  Nb and Ti are important elements in the present invention, and as described above, one or both of them are contained in a total of 0.01 to 0.25%. At that time, each is included in the following range.

  Nb remarkably suppresses recrystallization when the γ phase is processed in hot rolling, and remarkably promotes the formation of a processed texture in the γ phase. Thereby, {100} <011> to {111} <011> orientation groups develop. From this viewpoint, Nb needs to be added in an amount of 0.005% or more. Moreover, it is preferable to add 0.015% or more. However, if the amount of Nb added exceeds 0.100%, the Young's modulus in the rolling direction decreases, so the upper limit is made 0.100%. Although the reason why the Young's modulus in the rolling direction decreases due to the addition of Nb is not clear, it is presumed that Nb affects the stacking fault energy of the γ phase. From this viewpoint, the content is preferably 0.060% or less.

  Ti is also important for developing {100} <011> to {111} <011> orientation groups. Ti forms nitrides in the high temperature region of the γ phase, and suppresses recrystallization when the γ phase is processed in hot rolling in the same manner as Nb. Further, when B is added, the formation of Ti nitride suppresses the precipitation of BN, so that solid solution B can be secured. This promotes the development of a texture preferable for improving the Young's modulus. In order to obtain this effect, 0.002% or more of Ti needs to be added. On the other hand, if Ti is added in an amount exceeding 0.150%, the workability deteriorates remarkably, so this value is made the upper limit. From this viewpoint, the content is preferably 0.100% or less. More preferably, it is 0.060% or less.

  N is an impurity, and the lower limit is not particularly set. However, if it is less than 0.0005%, the cost becomes high, and so much effect cannot be obtained, so 0.0005% or more is preferable. Further, N may form Ti and nitride to suppress recrystallization of the γ phase, so it may be positively added. However, N reduces the recrystallization suppressing effect of B to 0.0100% or less. suppress. From this viewpoint, the content is preferably 0.0050%, more preferably 0.0020% or less.

  B is an element that significantly suppresses recrystallization by adding Nb together and enhances hardenability in the solid solution state, and is thought to affect the variant selectivity of crystal orientation during the transformation from austenite to ferrite. It is done. Therefore, it is considered that the development of {100} <011> to {111} <011> orientation groups, which are orientations that increase the Young's modulus, is promoted. From this viewpoint, it is preferable to add 0.0005% or more. On the other hand, even if B is added in excess of 0.0100%, no further effect is obtained, so the upper limit is made 0.0100% or less. Further, when B is added in excess of 0.005%, workability may be deteriorated, so 0.0050% or less is a preferable upper limit. More preferably, it is 0.0030% or less.

Mo ranges from 0.005 to 0.500%, Cr ranges from 0.005 to 1.000%, W ranges from 0.005 to 1.500%, Cu and Ni range from 0.005 to 0.350%, and As described above, it is desirable to add one or more in a range satisfying (Formula 2). These elements, like Mn, change the stacking fault energy in the γ phase to affect the hot-rolling texture formation and variant selection during transformation, and after transformation, the thickness of the surface layer of the hot-rolled sheet { 110} <111> and {110} <112>, and {100} <011> to {111} <011> orientation groups in the central portion of the plate thickness are developed and contribute to improving the Young's modulus. In order to obtain this effect, it is preferable to contain 0.005% or more of at least one of these elements.
On the other hand, as described above, the upper limit of the content of these elements is 0.500% for Mo and 1.000 for Cr as a range that does not increase {332} <113>, which is the origin of the orientation that decreases the Young's modulus. %, W is preferably 1.500%, and Cu and Ni are preferably 0.350%.

Since Ca, Rem, and V have the effect of increasing mechanical strength or improving the material, it is preferable to contain one or more as required.
If the addition amount of Ca and Rem is less than 0.0005% and the addition amount of V is less than 0.001%, sufficient effects may not be obtained. On the other hand, when Ca and Rem are added so that the addition amount exceeds 0.1000% and the addition amount of V exceeds 0.100%, ductility may be impaired. Therefore, Ca, Rem and V are preferably added in the range of 0.0005 to 0.1000%, 0.0005 to 0.1000% and 0.001 to 0.100%, respectively.

Next, the reasons for limiting the manufacturing conditions other than the hot rolling shape ratio and the coiling temperature will be described.
Steel is melted and cast by a conventional method to obtain a steel piece to be subjected to hot rolling. Although this steel slab may be a forged or rolled steel ingot, it is preferable to manufacture the steel slab by continuous casting from the viewpoint of productivity. Moreover, you may manufacture with a thin slab caster.

Usually, the steel slab is cooled again after casting, and then heated again for hot rolling. In this case, it is preferable that the heating temperature of the steel slab when hot rolling is 1100 ° C. or higher. This is because when the heating temperature of the steel slab is less than 1100 ° C., Nb and Ti are not sufficiently dissolved, and the recrystallization suppressing effect is remarkably reduced, thereby preventing the formation of a texture suitable for increasing the Young's modulus. or is because the finishing temperature of hot rolling be set to Ar ₃ transformation point or more becomes difficult. In order to heat the steel slab efficiently and uniformly, the heating temperature is preferably 1150 ° C. or higher. The upper limit of the heating temperature is not specified, but when heated to over 1300 ° C., the crystal grain size of the steel sheet becomes coarse and the workability may be impaired. Also, a process such as continuous casting-direct rolling (CC-DR) in which hot rolling is performed immediately after casting the molten steel may be employed.

  In the production of the steel sheet of the present invention, the conditions for hot rolling at 1100 ° C. or lower are important, and the definition of the shape ratio is as described above. In addition, the diameter of a rolling roll is measured at room temperature, and it is not necessary to consider the flatness during hot rolling. The entry side and exit side plate thicknesses of each rolling roll may be measured on the spot using radiation or the like, or may be calculated from the rolling load in consideration of deformation resistance and the like. Further, the hot rolling at a temperature exceeding 1100 ° C. is not particularly defined and may be appropriately performed. That is, the rough rolling of the steel slab is not particularly limited and may be performed by a conventional method.

  In hot rolling, the rolling reduction to 1100 ° C. or lower and the final pass is 40% or higher. This is because even after hot rolling above 1100 ° C., the processed structure is recrystallized, and the effect of developing the texture of the hot-rolled sheet cannot be obtained.

  1100 ° C. or less, the reduction ratio until the final pass is a numerical value expressed as a percentage obtained by dividing the difference between the plate thickness of the steel plate at 1100 ° C. and the plate thickness of the steel plate after the final pass by the plate thickness of the steel plate at 1100 ° C. It is. The reason why the rolling reduction is 40% or more is that if it is less than 40%, the texture that increases the Young's modulus in the rolling direction is not sufficiently developed. From this viewpoint, 50% or more is preferable. Although there is no particular upper limit, increasing the rolling reduction to 1100 ° C. or less and the final pass to more than 95% not only increases the load on the rolling mill, but also changes the texture and starts to lower the Young's modulus. % Or less is preferable. From this viewpoint, 90% or less is more preferable.

The temperature of the final pass of hot rolling is not less than the Ar ₃ transformation point. This is because rolling that is less than the Ar ₃ transformation point develops a texture unfavorable for Young's modulus. Further, if the temperature of the final pass of hot rolling exceeds 900 ° C., it is difficult to develop a texture preferable for improving the Young's modulus in the rolling direction. In order to improve the Young's modulus in the rolling direction, it is preferable to lower the rolling temperature of the final pass to 850 ° C. or lower on the condition that it is not lower than the Ar ₃ transformation point.

  When carrying out hot rolling, it is preferable to perform one or more passes of different peripheral speed rolling with a different peripheral speed ratio of the rolling roll of 1% or more. When different peripheral speed rolling with a difference in peripheral speed between the upper and lower rolling rolls is performed, shear strain is introduced near the surface layer and the formation of a texture is promoted, so the Young's modulus is improved compared to the case where different peripheral speed rolling is not performed. To do. Here, the different peripheral speed ratio in the present invention is a value obtained by dividing the peripheral speed difference between the upper and lower rolling rolls by the peripheral speed of the low peripheral speed roll in percentage. Further, the different peripheral speed rolling of the present invention has no particular difference in the effect of improving the Young's modulus regardless of the upper and lower roll peripheral speeds.

In order to improve the Young's modulus, the higher the different peripheral speed rate of the different peripheral speed rolling, the better. Therefore, the different peripheral speed rate is preferably 5% or more than 1% or more, and more preferably, different peripheral speed rolling is performed with a different peripheral speed ratio of 10% or more, but the different peripheral speed ratio is 50% or more. This is difficult at present.
Moreover, although the upper limit of the number of different peripheral speed rolling passes is not particularly specified, from the viewpoint of accumulation of introduced shear strain, a larger Young's modulus improvement effect can be obtained from the viewpoint of accumulation, so all passes of rolling at 1100 ° C. or lower are obtained. Different circumferential speed rolling may be used. Usually, the number of finishing hot rolling passes is up to about 8 passes.

  The hot-rolled steel sheet produced by the above method is pickled and then cold-rolled in a range of 30 to 80% reduction. Setting the rolling reduction to less than 30% causes plate thickness accuracy and shape defects, so this value is set as the lower limit. On the other hand, when the rolling reduction exceeds 80%, the load on the cold rolling machine increases and the degree of integration of the {110} <001> orientation, which is an orientation that lowers the Young's modulus, increases. From this viewpoint, it is more desirable to set it to 65% or less. From the viewpoint of leaving the {110} <111> orientation or {110} <112> orientation more strongly on the steel sheet surface layer, the cold rolling reduction is desirably 55% or less.

  At the time of annealing, the average heating rate from room temperature to 650 ° C. is 3 to 300 ° C./s. If the heating rate is less than 3 ° C./s, recrystallization occurs during heating and the texture breaks down. From this viewpoint, it is preferably 8 ° C./s or more, and more preferably 15 ° C./s or more. The texture is maintained as the heating rate increases. However, if it exceeds 300 ° C./s, no particular effect is produced, so this is the upper limit.

Annealing is performed at 650 ° C. or higher and Ac ₃ transformation temperature or lower for 1 second or longer. If it is 650 ° C. or lower, the work structure at the time of cold rolling remains as it is, so that the moldability is remarkably lowered. Therefore, this temperature is set as the lower limit of annealing. On the other hand, if the annealing temperature exceeds the Ac3 transformation temperature, the texture is destroyed and the shape freezing property deteriorates, so this is the upper limit.

  After annealing, temper rolling with a rolling reduction of 10% or less may be performed inline or offline. Moreover, you may give hot dip galvanization or alloying hot dip galvanization according to a use. The composition of the galvanizing is not particularly limited, and besides zinc, Fe, Al, Mn, Cr, Mg, Pb, Sn, Ni, etc. may be added as necessary. In addition, you may perform temper rolling after galvanization and an alloying process.

  The alloying treatment is performed within a range of 450 to 600 ° C. When the temperature is lower than 450 ° C., alloying does not proceed sufficiently, and when the temperature is higher than 600 ° C., alloying proceeds excessively, and the plating layer becomes brittle, which causes problems such as peeling of the plating due to processing such as pressing. . The alloying treatment time is 10 s or longer. If it is less than 10 s, alloying does not proceed sufficiently. The upper limit of the alloying treatment time is not specified in particular, but since it is usually performed by heat treatment equipment installed in a continuous line, if it exceeds 3000 s, productivity is lost, or equipment investment is required, so the production cost is low. Get higher.

Prior to the alloying treatment, annealing at an Ac ₃ transformation temperature or lower may be performed according to the configuration of the manufacturing equipment. If the temperature is lower than this temperature range, the texture is hardly changed, so that the decrease in Young's modulus can be suppressed.

  Next, the present invention will be described with reference to examples.

  Steel having the composition shown in Table 1 was melted to produce a steel slab, and the steel slab was heated, followed by hot rolling and finish rolling under the conditions shown in Table 2. The finish rolling stand consists of seven stages, and the roll diameter is 650 to 830 mm. The finished plate thickness after the final pass was set to 2.3 mm to 7.2 mm. Further, in Tables 2 and 3, SRT [° C.] is the heating temperature of the steel slab, FT [° C.] is the temperature after the final pass of the rolling, that is, the finishing side temperature, and CT [° C.] is the coiling temperature. The rolling reduction is a value obtained by dividing the difference between the plate thickness at 1100 ° C. and the finished plate thickness by the plate thickness at 1100 ° C., and is expressed as a percentage. The shape ratio indicates an average value of the shape ratio in a pass rolled at a temperature of 1100 ° C. or lower. The cold rolling rate is a value obtained by dividing the difference between the thickness of the hot-rolled plate and the thickness after completion of cold rolling by the thickness of the hot-rolled plate, and is expressed as a percentage. The heating rate represents an average heating rate from room temperature to 650 ° C.

The blank in Table 1 means that the analysis value was less than the detection limit. Moreover, Formula 2 of Table 1 is Mn, Mo, W, Ni, Cu, Cr is the value of the middle side of the following (Formula 2) calculated by content [mass%] of each element, Formula 1 is C , Mn, Mo, Ni, Cu, Cr are values of Bs [° C.] of the following (formula 1) calculated by the content [% by mass] of each element.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
3.0 ≦ 3.2Mn + 9.6Mo + 4.7W + 6.2Ni + 18.6Cu + 0.7Cr
≦ 7.5 (Formula 2)

  Steel No. 1 in Table 1 R is a comparative example that does not satisfy the lower limit of the value of Formula 2, and S and U are comparative examples that do not satisfy the upper limit.

When the contents of Mo, W, Ni, Cu, and Cr are about impurities, for example, when Mo, W, Ni, Cu, and Cr in Table 1 are blank, the above (Formula 1) and (Formula 2) are set to 0. ).
Further, Ar ₃ and Ac ₃ shown in Tables 1 and 2 are Ar ₃ transformation temperature and Ac ₃ transformation temperature calculated from the following (formula 4) and (formula 5), respectively.
Ar ₃ = 901-325 × C + 33 × Si + 287 × P + 40 × Al
−92 × (Mn + Mo + Cu) −46 × (Cr + Ni) (Formula 4)
Ac ₃ = 910−203 × √C−15.2 × Ni + 44.7 × Si + 104 × V +
31.5 × Mo + 13.1 × W-30 × Mn-11 × Cr-20 × Cu +
700 × P + 400 × Al + 400 × Ti (Formula 5)
Here, C, Si, P, Al, Mn, Mo, Cu, Cr, Ni, W, and Ti are the content [% by mass] of each element, and 0 when the content is about the impurity. .

A tensile test piece based on JIS Z 2201 was collected from the obtained steel plate, a tensile test was performed based on JIS Z 2241, and the tensile strength was measured. Young's modulus was measured by both static tension method and vibration method.
Measurement of Young's modulus by the static tension method was performed by applying a tensile stress corresponding to ½ of the yield strength of the steel sheet using a tensile test piece according to JIS Z 2201. The measurement was performed 5 times, and among the Young's modulus calculated based on the slope of the stress-strain diagram, the average value of the three measured values excluding the maximum and minimum values was taken as the Young's modulus by the static tension method. The rate is shown in Table 3.

Also, X-rays with {100} <011>, {211} <011>, {111} <011>, {554} <225>, and {110} <001> orientations at the plate thickness 3/8 position The random intensity ratio and the X-ray random intensity in the {110} <112> orientation and {110} <111> orientation at the position of 1/16 thickness were measured as follows.
First, after mechanically polishing and buffing the steel plate, further electrolytically polishing to remove strain, and using a sample adjusted so that the 3/8 plate thickness portion and the 1/16 plate thickness portion become the measurement surface, X-ray Diffraction was performed. Note that X-ray diffraction of a standard sample having no accumulation in a specific orientation was performed under the same conditions. Next, ODF was obtained by the series expansion method based on {110}, {100}, {211}, {310} pole figures obtained by X-ray diffraction. From this ODF, the X-ray random intensity ratio in the above orientation was determined.

  Of these steel sheets, when hot dip galvanizing is performed after cold rolling annealing, the alloying hot dip galvanization is carried out by “melting” and further alloying treatment that is held at 520 ° C. for 15 seconds after hot dip galvanizing. When it was given, it was written as “alloy”.

The results are shown in Table 3. Incidentally, the Young's modulus of the column of RD is the rolling direction (R ollinng D irection), TD means transverse direction is the direction of the rolling direction and at right angles to (T ransverse D irection) respectively.
As is apparent from Table 3, when the steel having the chemical composition of the present invention was produced under appropriate conditions, the Young's modulus by the static tension method and the dynamic vibration method exceeded 215 GPa in both the rolling direction and the direction perpendicular to the rolling direction. And was able to.

  On the other hand, production No. Nos. 44 to 47 are steel Nos. Whose chemical components are outside the scope of the present invention. It is a comparative example using TW. Production No. No. 44 is an example when the amount of Mn added is low and the Ar3 transformation temperature is high. In this case, in order to perform hot rolling in the γ region, hot rolling must be performed at a high temperature exceeding 900 ° C., and texture formation is not sufficiently performed at the stage of hot rolling, so the Young's modulus decreases. . Production No. 45 is an example when the amount of Mn added is too high. In this case, the crystal orientation group (B) develops strongly, so the Young's modulus in the rolling direction decreases. Production No. Neither 46 nor 47 is an example in which Nb and Ti are not added at all, or the amount is too small and the total amount of Nb and Ti is insufficient. In this case, a high Young's modulus cannot be obtained because the texture is destroyed by recrystallization at any stage of hot rolling and annealing.

  Steel No. E, which is a comparative example of E. 12, when the rolling reduction at 1100 ° C. or lower is low in hot rolling, Production No. 1 which is a comparative example of I. In the case where the shape ratio at 1100 ° C. or lower is low as in No. 22, no significant development of the orientation is significant in the Young's modulus in the rolling direction during hot rolling. 12 does not satisfy the A / B ratio. As a result, the Young's modulus after cold rolling annealing is not improved. Steel No. Production No. 4 which is a comparative example of G. 17 shows an example in which the heating temperature of hot rolling is low. Also in this case, Nb and Ti cannot be sufficiently dissolved, and recrystallization during hot rolling cannot be suppressed, so that the texture development after cold rolling annealing is insufficient.

  Production No. which is a comparative example of Steel J. Since the cold rolling rate of No. 24 is too high, an orientation that lowers the Young's modulus in the rolling direction is developed, and the A / B ratio cannot be satisfied. Steel No. Production No. which is a comparative example of L. 28 shows the case where the heating rate at the time of annealing is low. In this case, recrystallization starts during annealing and the texture is broken. Steel No. Production No. which is a comparative example of P. 39 shows the case where annealing temperature is higher than Ac3 transformation temperature. Also in this case, the texture breaks down during annealing, and a high Young's modulus cannot be obtained.

  Steel plates were manufactured under the conditions shown in Table 4 using the steels D and N shown in Table 1. Production No. shown in the table. Reference numerals 49, 51, and 52 are examples in which different peripheral speed rolling was performed by changing the different peripheral speed ratios in the final three stages of the finish rolling stand including all seven stages, that is, five passes, six passes, and seven passes. . All the hot rolling conditions not shown in Table 4 are the same as in Example 1. Further, in the same manner as in Example 1, the tensile properties, the texture of the 3/8 plate thickness part and the 1/16 plate thickness part, and the Young's modulus were measured. Neither hot dipping nor alloying hot dipping is performed. The results are shown in Table 5.

  As is clear from this, when hot rolling the steel having the chemical composition of the present invention under appropriate conditions, adding 1% or more of different peripheral speed rolling promotes the formation of texture and further improves the Young's modulus. To do.

The high Young's modulus steel sheet of the present invention is used for automobiles, home appliances, buildings and the like. In addition, the high Young's modulus steel sheet of the present invention includes a hot-rolled steel sheet in a narrow sense without surface treatment, and a broad-sense hot-rolled steel that has been subjected to surface treatment such as hot dip Zn plating, alloyed hot dip Zn plating, electroplating for rust prevention. Includes steel sheets. Surface treatment includes aluminum-based plating, hot-rolled steel sheets, formation of organic films and inorganic films on the surfaces of various plated steel sheets, coating, and combinations of these.
Since the steel sheet of the present invention has a high Young's modulus, it is possible to reduce the thickness of the steel sheet, that is, to reduce the weight as compared with the conventional steel sheet, and to contribute to global environmental conservation. Moreover, since the shape freezing property of the steel plate of the present invention is also improved, it becomes easy to apply the high-strength steel plate to press parts such as automobile members. Furthermore, since the member obtained by shaping | molding and processing the steel plate of this invention is excellent also in a collision energy absorption characteristic, it contributes also to the improvement of the safety | security of a motor vehicle.

It is a figure which shows ODF in a (phi) ₂ = 45 degree cross section, and main directions.

Claims (12)

% By mass
C: 0.010-0.200%
Mn: 0.10 to 2.50%
Containing
Si: 2.50% or less,
P: 0.150% or less,
S: 0.0150% or less,
Al: 0.150% or less,
N: limited to 0.0100% or less, and
Nb: 0.005 to 0.100%,
Ti: 0.002 to 0.150%
One or both of them are contained in a total of 0.01 to 0.25%, the balance is made of Fe and inevitable impurities, Bs [° C.] in the following (formula 1) is in the range of 450 to 700 ° C., The average value (A) of the X-ray random intensity ratio in the {100} <011>, {211} <011>, {111} <011> orientation at the thickness 3/8 position is 3.0 or more, {554} <225>, {110} <001> orientation X-ray random intensity ratio average value (B) is 5.0 or less and (A) / (B) ≧ 1.5 Rigid high strength cold rolled steel sheet.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
Here, C, Mn, Ni, Cr, and Mo are content [mass%] of each element. % By mass
Mo: 0.005 to 0.500%,
Cr: 0.005 to 1.000%
W: 0.005 to 1.500%,
Cu: 0.005-0.350%,
Ni: 0.005-0.350%
The high-rigidity and high-strength cold-rolled steel plate according to claim 1, wherein one or more of the above are contained in a range satisfying the following (formula 2).
3.0 ≦ 3.2Mn + 9.6Mo + 4.7W + 6.2Ni + 18.6Cu + 0.7Cr
≦ 7.5 (Formula 2)
Here, Mn, Mo, W, Ni, Cu, and Cr are the content [% by mass] of each element. % By mass
B: 0.0003 to 0.0100%
The high-rigidity and high-strength cold-rolled steel plate according to claim 1 or 2, characterized by comprising: % By mass
Ca: 0.0005 to 0.1000%,
Rem: 0.0005 to 0.1000%,
V: 0.001 to 0.100%
The high-rigidity and high-strength cold-rolled steel plate according to any one of claims 1 to 3, characterized by containing one or more of the following.   5. The X-ray random intensity ratio of one or both of the {110} <112> orientation and the {110} <111> orientation at a thickness of 1/16 is 3 or more. 2. A high-rigidity, high-strength cold-rolled steel plate according to item 1.   The high-rigidity and high-strength cold-rolled steel plate according to any one of claims 1 to 5, wherein a static Young's modulus in a rolling direction is 215 GPa or more.   A high-rigidity, high-strength hot-dip galvanized cold-rolled steel sheet, wherein the high-rigidity, high-strength cold-rolled steel sheet according to any one of claims 1 to 6 is hot-dip galvanized.   A high-rigidity and high-strength galvannealed cold-rolled steel sheet, wherein the high-rigidity and high-strength cold-rolled steel sheet according to any one of claims 1 to 6 is galvanized. . It is a manufacturing method of the high-rigidity high-strength cold-rolled steel plate of any one of Claims 1-6, Comprising: The steel piece which has a chemical component of any one of Claims 1-4 is 1100 degreeC. The total reduction ratio at 1000 ° C. or lower is 40% or more, the average value of the shape ratio X obtained by the following (formula 3) is 2.5 or more, and the temperature of the final pass is Ar ₃ transformation After hot rolling to a temperature of not less than 900 ° C and not more than Bs [° C] below (Formula 1) and in the temperature range of 450 to 650 ° C, cold rolling of 30 to 80% is performed. Further, high-rigidity and high-strength cold rolling characterized by performing annealing at an average heating rate of 3 to 300 ° C./s from room temperature to 650 ° C. and heating to 650 ° C. or higher and Ac ₃ transformation temperature or lower and holding for 1 second or longer. Steel plate manufacturing method.
Bs = 830-270C-90Mn-37Ni-70Cr-83Mo (Formula 1)
Shape ratio X = l _d / h _m (Formula 3)
l _d (contact arc length of hot-rolled roll and steel plate): √ (L × (h _in −h _out ) / 2),
h _m : (h _in + h _out ) / 2
L: Roll diameter,
h _in : plate thickness on the rolling roll entry side,
h _out : thickness of the roll exit side,
Here, C, Mn, Ni, Cr, and Mo are content [mass%] of each element.   The method for producing a high-rigidity and high-strength cold-rolled steel plate according to claim 9, wherein when performing the hot rolling, at least one pass of different peripheral speed rolling with a different peripheral speed ratio of 1% or more is performed.   A hot-dip galvanized cold-rolled steel sheet manufacturing method according to claim 7, characterized in that hot-dip galvanizing is applied to the surface of the steel sheet manufactured by the method according to claim 9 or 10. Manufacturing method of galvanized cold-rolled steel sheet.   It is a manufacturing method of the galvannealed cold-rolled steel sheet of Claim 8, Comprising: After giving the hot-dip galvanizing to the surface of the steel plate manufactured by the method of Claim 9 or 10, it is 450-600 degreeC. A method for producing a high-rigidity and high-strength galvannealed cold-rolled steel sheet characterized by performing a heat treatment for 10 seconds or more in a temperature range of

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