TWI276692B - High strength cold rolled steel sheet and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a high strength cold rolled steel sheet consisting of 0.015% or less of C, 1.5% or less of Si, 0.4 to 3% of Mn, 0.15% or less of P, 0.02% or less of S, 0.1 to 1% of sol.Al, 0.01% or less of N, 0.2% or less of Ti, by mass %, and the balance of Fe and inevitable impurities. In this steel sheet, 1 <= ([Ti]/48)/([C]/12+[N]/14) is satisfied, in which [M] represents the content of the element M. Since having the superior deep drawability and the TS of 340 to 590 MPa, the high strength cold rolled steel sheet of the present invention is preferably used for automobiles parts difficult to be press formed, such as a side outer panel and a door inner panel.

Description

1276692 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a high-strength cold-rolled steel used for automobiles, home electric appliances, and the like; a plate, particularly for a tensile strength of 300 to 590 MPa (TS) , tensile strength) High-strength cold-rolled steel sheet excellent in deep drawability and a method for producing the same. [Prior Art] Conventionally, in an automobile part in which the outer outer panel and the inner panel of the door are difficult to form, φ is an IF having an excellent deep drawability of about 270 MPa and an r value of 1.8 to 2.0 (I nterstitia 1) F ree, seamless) soft cold rolled steel sheet (SPC 2 7 0 E, F ). In recent years, as the demand for weight reduction of automobile bodies has been further increased, IF high-strength cold-rolled steel sheets having a TS of 340 to 590 MPa have been developed for such difficult-to-shape parts. However, if these parts are to be used, the south strength cold-rolled steel sheet with a TS of 340 to 390 MPa and an r value of about 1.7 is used; the south strength cold-rolled steel sheet having a TS of about 440 MPa and an r value of about 1.5 is used. And when the high-strength cold-rolled steel sheet with a TS of about 590 MPa and an r value of about 1.9 is formed, cracks are likely to occur at the stretched portion, so any high-strength cold-rolled steel sheet can be applied only in actual conditions. Shallow stretch parts. Further, a high-strength cold-rolled steel sheet having a TS of 340 to 590 MPa and having a higher r value is required. Specifically, it is desirable that the TS is 340 to 400 MPa and has an r value of 1.8 or more, and is an r value of 4 〇〇 to 590 MPa and more than 1.6 or more, preferably 1. 7 or more. Heretofore, as a method of increasing the r value, it is known to use an IF steel in which c and n are extremely reduced and a large amount of T i and N b are added, after hot rolling at 680. (: The above 312XP / invention manual (supplement V94_〇5/941 〇5〇2〇1276692) coiled at a high temperature, so that the solid solution C and N are reduced in intensity and coarsened the precipitate, and promotes favorable during annealing. A method for producing and growing recrystallized grains of a set of r values. As a method of the same, it is disclosed in Japanese Patent Laid-Open No. Hei. No. Hei. No. 6-1 0 8 15 5 and Japanese Patent No. 3 2 9 1 6 3 9 In the publication, it is disclosed that there is a method in which T IF (C, S) is generated by using an IF steel in which C and N are minimized and T 1 is added, and a set structure favorable for r value is developed at the time of annealing. In the method disclosed in Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. When a large amount of IF high-strength cold-rolled steel sheet having 340 MPa or more TS is added to P and Μη, a large amount of Fe-Ti-P, Fe-Nb-P, and the like are formed at the grain boundary during coiling after hot rolling. Further, since the η itself is large in number, the value of r is remarkably lowered. Further, in the method disclosed in Japanese Patent No. 3 2 921 369, the proposal is added. The amount P of 340MPa TS having the above deep drawn high-strength cold rolled steel sheet, but in the press molding, casting times the plate thickness due to uneven tissue caused by the segregation of P in the direction of the rupture occurs.

On the other hand, there is also a proposal to work on the manufacturing method to increase the r value. For example, a method of performing finish rolling while lubricating in the α region during hot rolling is disclosed in Japanese Laid-Open Patent Publication No. Hei 7-108-76. A method of applying 1 to 50% of a rolling at a temperature of 550 to 750 ° C during annealing is disclosed in Japanese Laid-Open Patent Publication No. Hei 9- 2 7 9 2 4-9. The amount of S i, η η, and P of the steel to be added to N b and B is controlled and disclosed in Japanese Patent Laid-Open Publication No. Hei. No. 2 0 0 1 - 1 3 1 6 4 3, and is applied after pickling, cold rolling, and annealing. 3 to 5% of the rolling, and again subjected to pickling and passing through a hot-dip galvanizing line. 8 312 ΧΡ / invention manual (supplement) /94-05/94105020 1276692 The board is cold-rolled to a cold-rolled steel sheet at a rolling reduction ratio of 50 to 9 Ο %; and the cold-rolled steel sheet is 750 to 8 7 Manufactured by continuous annealing at 0 °C or by closed-loop annealing at 600 to 750 °C; 480 S CTS 580 + 0. 1 7/{([Ti] + 0· 08x[ sol· A1 ])x[P] } (5) Here, [Μ] is the content of the element Μ (% by mass) . [Embodiment] The inventors of the present invention investigated the influence of various alloying elements on the r value of the IF high-strength cold-rolled steel sheet, and obtained the following findings.

i) If the amount of s ο 1 . A 1 is added in a larger amount than in the previous high-strength cold-rolled steel sheet, the r value is remarkably improved. This effect is particularly noticeable when adding Μη of 0.4% or more. Ii) The addition of Si and yttrium is effective to increase the r value. Iii) A higher r value can be obtained by making P, sol · Al, Ti and, if necessary, the amount of Nb suitable for the coiling temperature after hot rolling. The present invention has been made based on the above findings, and the details thereof will be described below. 1) sol·A1 amount and r value In order to investigate the relationship between s ο 1 . A 1 amount and r value, the following test was performed. C ···0· 0 0 2 % , S i : 0· 2 5 % , P : 0 . 0 8 % &gt; S ·· 0 · 0 0 7 % , N b : 0 . 0 1 5 %, T i : 0 · 0 3 %, N : 0 · 0 0 2 %, B : 0 · 0 0 1 % is constant, and s ο 1 . A 1 amount is 0 · 0 1 to 1 · 2 %, Μ η The flat steel of 0. 6 to 1.8% change is heated at 1 250 °C, and then hot rolled into a hot-steel plate with a thickness of 3 mm and applied at 580 °C. Take 1 hour of simulated heat treatment. The hot-rolled steel sheet is cold-rolled to form a cold-rolled steel sheet having a thickness of 0.75 mm, and subjected to continuous annealing at 80 ° C for 60 seconds, and an elongation of 0.7% is applied. Tempering and rolling 312XP / invention manual (supplement) / 94-05/94105020 1276692 system. Thereafter, the r value and TS were measured in the following manner. The JIS No. 5 test piece was taken from the rolling direction, the direction of 45° with respect to the rolling direction, and the direction of the rolling direction of 90°, and the r value and TS for each direction were measured, and the following formula was obtained. The average value inside the steel plate. Average = ([T〇]+2[T45] + [T9〇])/4 Here, [T. ] is the rolling direction, [T 4 5 ] is a direction of 45° with respect to the rolling direction, and [T9〇] is an r value or TS of 90° with respect to the rolling direction.

Fig. 1 shows the relationship between s ο 1 . A1 amount and r value, T S . In the figure, the black circle is the result of the Μ η amount being 1.8%, and the white circle is s ο 1 . The total amount of A 1 and Μ η is 1.8%. When the amount of Μ η is 1.8%, the value of r is s ο 1 . A 1 is 0. 1% or more is 1.6 or more, and 0.2 to 0.7% is 1. 7 or more. 0. 7 % is lowered. T S exceeds 460 MPa in a case where sol. Al is 0.1% or more, and increases in proportion to the amount of sol. At this time, the TS increase per 1% of the amount of sol. Al was 35 MPa. It has about the same solid solution strengthening ability as Μη, so if the total amount of s ο 1 . A 1 and Μ η is 1.8%, the relationship between the T S and the r value when the intensity of the white circle is kept constant can be obtained. From this, it can be seen that by adding s ο 1 . A 1 and reducing Μ η, a higher r value can be obtained at the same intensity. Further, if s ο 1 . A 1 exceeds 1%, fine A 1 N is precipitated at the Worthfield iron grain boundary during continuous casting of the steel blank, and the grain boundary is embrittled, and the bending of the flat steel embryo is corrected. At the time of rough rolling and subsequent rolling, it is easy to crack on the surface of the flat steel. Then, due to the cracking of the surface of the flat steel, it is easy to cause surface defects due to the steel scale, and the surface quality of the final product is remarkably lowered. 8 312XP / invention manual (supplement) /94-05/94105020 1276692 From the above results, even if TS exceeds 400 MPa, if the amount of sol.Al is 0.1 to 1%, preferably 0.2 to 0.7% Further, a high r value of 1.6 or more, preferably 1.7 or more is obtained. : s ο 1 . The reason why the high value of r can be obtained when the amount of A 1 is from 0.1 to 1% is as follows. That is, A 1 is an element that raises the metamorphic point of Ar 3 , so when hot rolling, the ferrite is transformed into ferrite iron, and then the precipitation of carbides is promoted in the α region of high temperature, and solid solution C Since the carbide is coarsened and coarsened, a recrystallized aggregate structure favorable for the r value is formed at the time of annealing, and the r value is increased. In addition, it is also helpful to improve the r value by pushing φ to measure the change in the cold-rolled structure caused by A 1 . 2) The amount of Si, P and r are the relationship between the amount of Si and P and the value of r. C: 0.002%, Μη: 1%, S i : 0. 0 0 7 %, s ο 1 . A 1 : 0 2 5 % , N b : 0 . 0 2% , T i : 0 . 0 1 % , N : 0 . 0 0 2 %, B : 0 . 0 0 10/〇 is constant, and the amount of Si is 0. The 0 0 5 to 1.5% 'P quantity of flat steel embryos varying from 0. 0 0 3 to 0.15 % was subjected to the same test as in the case of 1).

In Fig. 2, the relationship between [Si] + 10x [P] and the value of r is shown. In addition, the numbers in the figures indicate the amount of Si. When the steel of the present invention having a sol. Al content of 0 · 2 5 % satisfies the following formula (2), it is known that a high r value of 1.7 or more can be obtained. 0.3^ [Si] + 10x [P]^ 1.4 (2) Here, [M] represents the content (% by mass) of the element cerium. However, if the amount of S i and 1 0 X 均 exceeds 1.5%, the deterioration of the r value is large, so that the amounts of S i and P are respectively 1.5% or less and 0.15% or less. In addition, in the case of applying the alloyed hot-dip galvanized steel plate 312XP/invention specification (supplement)/94-05/94105020 10 8 1276692 to the high-strength cold-rolled steel sheet of the present invention, such elements are liable to cause poor adhesion of the bonding layer, so Let the amount of S i be 0.5% or less, and the amount of P be 0. 0 8 % or less. Further, since S i and P are effective elements for solid solution strengthening of the ferrite iron, the amount of Si is 0. 0 0 3 % or more, and the amount of P is 0. 0 1 % or more. 3) Other ingredients

C : C is a combination of T i and N b to form a carbide. If the amount is more than 0.015%, the amount of the carbide is increased and the value of r is remarkably lowered. Therefore, the amount of C is 0. 0 1 5 % or less, preferably 0. 0 0 8 % or less, more preferably Less than 0. 0 0 4 %. However, C also has an effect of increasing the strength by precipitation strengthening in the T i C and N b C type. Therefore, for example, the steel having a TS of 4 4 Ο Μ P a contains 0.04% or more. . In other words, when the amount of C is from 0.004 to 0.008%, and Ti and Nb are added at a ratio of 1.0 or more to the atomic ratio of C, the decrease in the r value can be suppressed and the drawing strength can be increased. In addition, in the case where the amount of C is less than 0.05 0 5 %, the iron particles of the ferrite are coarsened during annealing, and the surface texture is liable to be rough during press forming, so that the amount of C is 0. 0 0 0 5 More than % is better. Μη : Μη is an element which increases strength by solid solution strengthening and is an indispensable element in high-strength cold-rolled steel sheets of I F . In order to obtain a T S of 340 MPa or more, the amount of Μ η must be 0.4% or more. On the other hand, if the amount exceeds 3%, the r value is remarkably lowered, so that the amount of Μ η is 3% or less, preferably 2 ° / 〇 or less, more preferably 1.5 % or less. Although the reason why the amount of Μη increases, the value of r is lowered is not necessarily clear, but it is considered that the value of r is lowered by the interaction of Μη with solid solution C. Furthermore, it is presumed that Μ η causes the Ar 3 metamorphic point to decrease, so that the precipitated carbide is finer during hot rolling, and the precipitation of the carbide is delayed and the solid solution C is increased, so that it is impossible to form an advantage during annealing. 11 312XP/Invention Manual ( Replenishment) /94-05/94105020 1276692 The recrystallization set structure at r values reduces the value of r. S : S is present in the steel in the form of a sulfide. If the amount exceeds 0.2%, the ductility is deteriorated. Therefore, the amount of S is 0.2% or less, preferably 0. 0% or less. Further, from the viewpoint of descaling and rust removing properties, the amount of S is desirably 0.04% or more. If the amount of k N : N exceeds 0.01%, fine A 1 N, N b N, N b ( C, N ) are precipitated at the ferrite grain boundary during continuous casting of the flat steel embryo. It is embrittled, and it is easy to crack on the surface of the flat steel when the flat steel is cast and coarsely rolled. Therefore, the amount of N is made 0.01% or less. In addition, the smaller the amount of N, the better, but the limit of φ in the current steelmaking technology is around 0.01 °C. T i : T i has an effect of making the crystal grains after hot rolling fine, and forming precipitates with C and N to reduce the solid solution C and N and increase the r value. In order to fully exert such a T i effect, it is necessary to satisfy the following formula (1) and add T i . 1 ^ ([Ti]/48)/([C]/12+[N]/14) (1) Here, [M] is a content (% by mass) indicating the element Μ.

However, even if the amount of T i is more than 0.2%, the rise of the r value is still small, so that the amount of T i is 0.2% or less. Further, in the case where the high-strength cold-rolled steel sheet of the present invention is subjected to alloying hot-dip galvanizing, the amount of T i is preferably 0.4% or less from the viewpoint of preventing plating. Further, in order to obtain a high r value due to the addition of T i , the amount of Ti is preferably 0.005% or more. The remainder is Fe and unavoidable impurities. In addition to the above ingredients, NbO. 002% or more is added, and it is preferable to obtain a higher r value. Further, at this time, it is necessary to adjust the amounts of Nb, Ti, C, and N in such a manner as to satisfy the following formula (3). ([Nb]/93+[Ti]/48)/([C]/12+[N]/14) (3) 312XP/Invention Manual (supplement)/94-05/94105020 12 8

1276692 °·00^ [Sb] + [Sn]/2^〇 2 (4) where ^ [M] is the content (% by mass) of the element M. By S h, S π &gt; on &lt; addition, it can prevent annealing caused by flat steel embryo heating, coiling annealing furnace (BAF), continuous annealing flow line (c AL), continuous hot-melt plating (CGL), etc. When the surface layer is nitrided and oxidized, and the change of the viscosity of the money layer is not changed. Further, zinc oxide adhesion in the zinc bath is prevented&apos; and the appearance of the plating layer is improved. Further, Sb and Sn alleviate the deterioration of the fatigue properties of the surface and the deterioration of the toughness after the stretch forming. However, if the amount of 'S b, S η exceeds 〇. 2%, the galvanizing tightness is deteriorated. 4) Manufacturing method The high-strength cold-rolled steel sheet of the present invention has a step of heating the steel preform at (Ar3 metamorphosis point -20) to (Ar3 metamorphosis) by having a step of heating the upper flat steel embryo at 1080 to 1350 °C. Point +150). (The step of hot rolling to form a hot-rolled steel sheet at the end of the temperature, the case of adding Nb to the hot-rolled steel sheet satisfies the following formula (5); and the case where the nb is added, the coiling temperature of the full-type (6) is applied to the CT The winding step, the rolled sheet is cold-rolled at a rolling reduction ratio of 50 to 90% to form a cold-rolled steel sheet, and the cold-rolled steel sheet is continuously annealed at 75 to 80 °C. Or 750 SCTTS 5 80 + 0.1 7/{([Ti] + 0.08x[sol.Al])x[P]} ··· 480^CT^ 580+0.17/((0. 6x[Nb] + [Ti]+0. 08x[sol. A1 ])x[P]} where [M] is the content of the element M (% by mass) ).

In order to make the Fe-Ti-P, Fe-Nb-P 3 UXP/invention specification (supplement)/94-05/941 〇5〇2〇, the closed zinc flow line good ore layer formed in the iron block The oxidation and viscosity of the compound and the flat-rolling after the composition are fully dissolved in the following hot-strip steel step, and the P 14 1476692 of 6 0 〇(5) ...(6) must be fully dissolved. The heating temperature SRT before rolling is 1 Ο 80 °C or higher. However, if it exceeds 1 3 50 °C, the surface quality deteriorates, so S R T must be 1 3 50 °C or less. In order to obtain an excellent appearance, it is preferable not only for the first pot scale but also for the second pot scale generated during hot rolling. Further, in hot rolling, heating may also be carried out via a rod heater. The finishing rolling temperature F D T of the hot rolling must be (A r 3 metamorphic point - 2 0 ) to (A r 3 metamorphic point + 1 50 ) t: in order to refine the microstructure after hot rolling.

The coiling temperature after hot rolling greatly affects the r value of the cold rolled steel sheet of the present invention in which A 1 , P, T i and optionally N b are added in combination. This is because the IF steel to which P is added is not preferable for the r value as described above, and P compounds such as Fe-Ti-P and Fe-Nb-Ρ are easily formed. In general, when the coiling temperature is high and the precipitates are coarsened and the solid solution C is decreased, the r value is remarkably improved. However, if the coiling temperature exceeds the appropriate temperature and is high, a P compound as described above is formed, and the r value is remarkably lowered. Therefore, for the steels in which various kinds of A 1 , P, T i and, if necessary, N b are added, the most suitable coiling temperature is investigated, and as a result, it is found that the coiling temperature CT exceeds 580 + 0.17 / { in the case where no Nb is added. [Ti]+0.08x[sol.Al])x [P]}, if the case of adding Nb exceeds 580 + 0·17/{(0·6χ [N b ] + [ T i ] + 0 · 0 8 X [ s ο 1 · A 1 ] ) X [ Ρ ] }, a telluride is formed and the r value is significantly lowered. Further, when the coiling temperature C T is lower than 480 ° C, even if the P compound is not formed, the precipitation of carbides during winding is insufficient, and the r value is deteriorated. Therefore, the coiling temperature CT must satisfy the above formula (5) or (6).

In addition, in the temperature range of the above formulas (5) and (6) (upper limit value - 4 0) to (upper limit value) °C 312XP / invention specification (supplement) /94-05/94105020 15 8 1276692 Rolling is better. In the cold rolling, from the viewpoint of increasing the r value, the rolling reduction ratio must be 50 to 90%, preferably 65 to 80%.

The annealing temperature A T is continuously annealed with C a 1 and C G L and must be 750 to 870 °C. At temperatures below 750 °C, recrystallization is not sufficient enough to achieve high r values. Moreover, characteristics such as elongation are significantly deteriorated. At temperatures above 870 °C, the steel sheet with a large amount of Μ η becomes annealed at a point beyond the A r 3 metamorphic point, the strength is extremely increased and extended, and the η value is significantly deteriorated. In order to achieve higher r value and high elongation for stability, annealing at a temperature of 820 °C or higher is preferred. Also, in the case of BAF annealing, since the annealing time is long, the annealing temperature AT must be 600 to 750 °C. For the cold rolled steel sheet after annealing, a zinc-containing plating layer may be applied via electroplating or molten plating as needed. Examples of the zinc-containing plating layer include galvanization, zinc alloy plating, and galvanized nickel alloy. Further, the organic film may be treated after plating. (Example) After the steels of steel No. A to X shown in Table 1 were dissolved, a 230 mm thick flat steel blank was continuously cast. The flat steel blank is reheated by the heating temperature SRT shown in Table 2, and hot rolled to a thickness of 3.2 mm by the completion rolling temperature FDT shown in Table 2, and the coiling temperature shown in Table 2 is used. CT will be taken. After the hot-rolled sheet was cold-rolled to a thickness of 0.8 mm, the annealing temperature AT shown in Table 2 was annealed by CAL, CGL, and BAF, and temper rolling was performed at an elongation of 0.8% to prepare a steel sheet No. 1 To 34. In addition, in CGL, the annealed steel plate is at 460. (: impregnation in a hot-dip galvanizing bath, followed by in-line alloying treatment furnace at 500 °C 16 312XP / invention specification (supplement) / 94-05/94105020 1276692 alloy The coating amount was 45 g/m2 per one side. Thereafter, the r value and TS were measured by the above method. Further, the surface defects were visually inspected and the surface quality was investigated. The results are shown in Table 2. Table 1 and Table 2 [Nb] in the uppermost formula is considered to be 0 when Nb is not added.

In the steel sheets No. 1 to 24 of the examples of the present invention, the TS was obtained from 340 to 40 OMPa, the r value was 1.8 or more, the TS was 400 to 590 MPa, and the r value was 1.6 or more, and the surface quality was also good. Further, when compared with the comparative example of the same strength, it is understood that the r value of the example of the present invention is remarkably high. In particular, if the amount of Μ η exceeds 1%, the effect can be clearly seen. On the other hand, in the steel sheet of the comparative example 2 2 2 25 to 34, the T S was 340 to 400 MPa, the r value was 1.8 or more, the TS was 400 to 590 MPa, and the r value was 1.6 or more. The steel plate No. 27, 28, and 29 of the conventional high-strength cold-rolled steel sheet corresponding to the high η η amount has a low r value. Further, in the steel sheets No. 30, 31, 32, 33, and 34, the ratio of (Nb + Ti) / (C + N), C, Si, Μη, P, sol. Al, and Nb are all outside the scope of the present invention, r The value is low. Among them, the amount of C, (Nb + Ti) / (C + N) ratio is not suitable, and the solid solution C and η η are coexisting steel sheets equivalent to conventional low carbon high strength cold rolled steel sheets. 3 0 Even if s ο 1 . A 1 is raised, a high r value cannot be obtained. Further, Nb or Nb and sol. Al are steel sheets Ν 3 3 1 and 3 4 outside the scope of the present invention, and the surface quality is poor. In addition, the steel sheet No. 25 which is equivalent to the conventional soft cold-rolled steel sheet SPC 2 7 0 F is compared with the steel sheet Νο·26 in which the amount of sol. And add s ο 1 . A 1, increase the r value of 312XP / invention manual (supplement) /94-05/94105020 17 8 1276692 The effect is still small.

312XP/Invention Manual (supplement)/94-05/94105020 18 1276692 $ lQI/[N]laI/s)/(8 inch/[u]+ls/[qN])(ss ¥^^oco οο·ζ

9CO °°z oco

I l 11⁄2^ ¥5^生 ¥^越 ΐ^φ ΐπΒφ ΐπΒφ

5S egg s

5S ss ¥SJ± ss

5S is

5S 9

Lo

Locd

L.I rz

l/Z

9CO

Inco 9.1 ulx2+ns

Is u.o 2 inch oo 0 gs oco

IS 900 cooo Z9 ζοο 900 卜 60 0 60

Is

Is 96.0

Is 061

OS 1001 19 ·0 ZO&quot;TNVi ^·0··ΟΪΓΖ·0··ώ lo&lt;?:qs S000 Ό §

8000 · 0 9S 200,0 § Z100 ·0

Locoo 9000 ·0

Locoo 10 ·0 scoo soo ·0 0£ _ 6000‘ggloo soirozol 9000 ·0 i 00000,ο 100 ·0

qN 9200 io 600 ·0 9S0

OIO 600 Ό 600.0 0910 090 090 Ό One CN1I00 ·0 990 ·0 zooo ·0 〇〇0·0 goo ·0〇〇0 9000 ,0 § )100 ·0 9CO0 卜 so .οΙόεο οι 9000.020

9000 Ό ISO 9000 , 0 § § 0,0

SCOOO

Loooo

OIOO 卜 00 9Ϊ00 9100 OOI00 io

ISO zzoo 010· so IZOO ·0

Lolo 1 ZIOO ·0 OOI00 ·0 2:00,0 itzoo ♦0 91000 10 ·0 9S0 ·0 61,0 i ZZOO ♦0

LOIO i ·0

_O

I inch ZOO ·0

Iv.os s 豪·0 oos 9CO.0

Loro Ξ ss 0 Bu·0 9CO.0

6S

Los

Los s.o coo

LOS ΚΓ0

SO coo 6Z.0

Gz.o lz.0 0ΖΌ

0°°I too 900 900 900 900 900 900 900 base d §·0 0 — oso § oso 020 00 bu 0 s ·0 so 1^0 900 900 oog 900 cooo 900 so 900 ocoo 2

I 190 Ό 9900 0090.0 0 990 · 0 0000 0000 G§ 00 Bu 0 09 Bu 0 i .0 1.0 oso 9Ό 6·0 6.1 ΖΊ

i.CNI 9*0 ocvi coCNi 3

LO.I oLOro

!S 10. 10

OCNI oz

OZ oz 09 10

ICNI 3

Logo 00100

ZZOO i )200

OHO onoo οειοο 0ΖΙ00 Ξ Ό 0卜00 iro^oo ΟΟΓ0 so

Is 9CO00 10

OCNIOO ooros 06100 010 ·0 〇〇·0 10 See 00 —0

rCNI

OCNI ocozoo ro οδ.οζ.ε CN1

00 Ό I 8ΙΌ §0·0 Bu I°

r-HooIOO 9100 s 0·0 9Z00 L.o 00 9S0 •ONl I&lt;

V

OQ 0 a 0

H 0 d

H s

I il Λ

Ik

X 0ss56/s46/ip}s)_^^SRa®/dxzIe 8 1276692 Table 2 Steel Plate No. Steel No. Hot Rolling Condition Annealing Condition Annealing Streamline Mechanical Properties Surface Quality Zhao 580+0.17/((0. 6[ Nb]+ [Ti]+0. 08x[sol. Al]) χ[Ρ]Γ Remarks SRT (°C) FDT CC) CT CC) AT CC) r value TS (MPa) 1 A 1250 890 640 840 CGL 1.89 347 〇 666 Inventive Example 2 1250 890 540 720 BAF 1.86 342 〇 666 Inventive Example 3 1280 990 640 840 CGL 1.85 345 〇 666 Inventive Example 4 1220 850 640 840 CGL 1.90 349 〇 666 Inventive Example 5 1220 780 640 840 CGL 1.77 340 〇 666 Inventive Example 6 B 1220 870 620 770 CGL 1.83 408 〇 622 Inventive Example 7 1220 870 620 840 CGL 1.87 395 〇 622 Inventive Example 8 1220 870 620 870 CGL 1.88 390 〇 622 Inventive Example 9 1300 975 620 870 CGL 1.85 385 〇 622 Inventive Example 10 1220 840 620 870 CGL 1.90 392 〇 622 Inventive Example - 1220 760 620 870 CGL 1.85 387 〇 622 Inventive Example C 1220 850 580 820 CGL 1.81 446 〇 618 Inventive Example 13 1220 850 615 820 CGL 1.85 444 〇 618 Inventive Example 14 D 1220 850 620 820 CGL 1. 66 440 〇630 Inventive Example 15 E 1250 940 600 830 CGL 1. 73 442 〇 603 Inventive Example 16 F 1220 860 680 800 CGL 1.75 403 〇 - Invention Example 17 G 1290 840 580 860 CAL 1.60 530 〇 599 Inventive Example 18 H 1220 890 670 850 CGL 1.90 340 〇 698 Inventive Example 19 I 1220 840 600 820 CGL 1.90 440 〇 611 Inventive Example 20 J 1220 830 580 790 CAL 1.85 445 〇 602 Inventive Example 21 K 1220 830 600 830 CGL 1.96 440 〇 609 Inventive Example 22 L 1220 850 600 840 CGL 1.89 442 〇613 Inventive Example 23 M 1220 850 600 840 CGL 1.85 449 〇608 Inventive Example 24 N 1220 850 600 830 CGL 1.82 445 〇 611 Inventive Example m 0 1200 910 680 830 CGL 1.82 289 〇 - Comparative Example 26 P 1200 930 680 830 CGL 1.83 294 〇 793 Comparative Example 27 Q 1230 880 640 830 CGL 1.69 340 〇697 Comparative Example 28 R 1220 880 640 820 CGL 1.62 392 〇642 Comparative Example. 29 S 1220 840 640 800 CGL 1.46 440 〇 632 Comparative Example 30 T 1220 890 680 770 CGL 1.12 405 〇 682 Comparative Example 31 U 1270 950 640 820 CAL 1.40 480 X A comparative example ^32 V 1270 840 640 800 CAL 1.43 450 〇641 Comparative Example 33 w 1270 950 600 820 CAL 1.49 475 〇599 Comparative Example '34 X 1 290 1000 600 820 CAL 1.52 444 X 595 Comparative Example XI: Those exceeding 800 °C are considered to be -. *2: The surface of the crucible is free from defects or within the allowable range; X is deteriorated due to surface defects of the scale. 312XP/Invention Manual (Supplement)/94·05/94105020 1276692 [Simplified Schematic Description] Fig. 1 is a view showing the relationship between the amount of sol. A1 and the r value and TS. Fig. 2 is a graph showing the relationship between [Si] + 10x [P] and r value.

312XP/Invention Manual (supplement)/94-05/94105020 21

Claims (1)

—— _~ 2ϋΒ6 - 4 SEP Year of the year 7 曰 repair (more) original &amp; owe ten, the scope of application for patent: -^ 1. A high-strength cold-rolled steel sheet characterized by a mass% of C: 0 0 1 5 % or less, S i : 1 · 5 % or less, Μ η ·· (K 4 to 3%, PU 5 % or less, S: 0 · 0 2 % or less, acid soluble A 1 (hereinafter referred to as s ο 1 · A 1 ) : 0 . 1 to 1 %, N : 0 . 0 1 % or less, T i : 0 . 2 % or less, the residual portion is F e and unavoidable impurities, and the following formula is satisfied (1); 1 ^ ([Ti ]/48)/( [C]/12 + [N]/14) (1) where [M] represents the content of the element ( (% by mass). The high-strength cold-rolled steel sheet of the first item of the patent range, wherein the mass ° / 之 s ο 1 · A 1 ·· 0 · 2 to 0.7%. 3. High-strength cold rolling as in claim 1 Steel sheet which satisfies the following formula (2); 0.3^ [Si] + 10x [P]^ 1.4 (2) wherein [M] represents the content of the element ( (% by mass). The high-strength cold-rolled steel sheet of item 2, which satisfies the following formula (2); 0.3^ [Si] + 10x [P]^ 1.4 (2) [M] represents the content of the element ( (% by mass). 5. The high-strength cold-rolled steel sheet of claim 1 which further contains N% of mass %: 0 · 0 0 2 to 0. 0 2 %, and satisfy the following formula (3); ([Nb]/93+[Ti]/48)/([C]/12+[N]/14) (3) where [M] represents an element Content of bismuth (% by mass) 6. High-strength cold-rolled steel sheet according to item 4 of the patent application, further containing N% of mass %: 0. 0 0 2 to 0. 0 2 %, and satisfying the following Equation (3); 22 326\Total file\94\94105020\94105020 (replacement)-1 1276692 ([Nb]/93+[Ti]/48)/([C]/12+[N]/14) (3) where [M] represents the content (% by mass) of the element M. 7. The high-strength cold-rolled steel sheet according to item 1 of the patent application, further containing % by mass: 0. 0 0 0 1 To 0. 0 0 3 ° / 〇 8. The high-strength cold-rolled steel sheet according to claim 6 of the patent application, further containing 5% by mass: 0. 0 0 0 1 to 0. 0 0 3 %. 9. The high-strength cold-rolled steel sheet according to item 1 of the patent application, further comprising Cm 0 · 0 3 to 0 · 5 % by mass %, N i : 0 · 0 3 to 0.5%, Cr: At least one element selected from 0.03 to 0.5%, Μ〇: 0.05 to 0.3%, and V: 0. 0 0 5 JL 0.5%. 1 0. The high-strength cold-rolled steel sheet according to item 8 of the patent application, further comprising C κκ 0 . 0 3 to 0 · 5 % by mass %, N i : 0 · 0 3 to 0.5%, Cr : 0. 03 ^ (L5%, M〇: 0.05 to 0.3% and at least one of [0.005 to 0.5% selected). 1 1 . The high-strength cold-rolled steel sheet according to item 1 of the patent application, further comprising at least one element selected from the group consisting of 31% by mass: 0.002 to 0.2% and 811: 0.002 to 0.2%, and satisfying The formula (4); 0. 0 0 2 ^ [Sb] + [Sn]/2^ 0. 2 (4) where [M] represents the content of the element Μ (% by mass). 1 2 . The high-strength cold-rolled steel sheet of claim 10, further comprising S b from 0% to 0. 2% and S η: 0. 0 0 2 to 0.2. At least one element selected from %, and satisfying the following formula (4); 0.0 0 2 ^ [Sb] + [Sn]/2^ 0. 2 (4) where [M] represents the content of the element Μ (quality%). 23 326\总档\94\94105020\94105020 (replacement)-1 1276692 1 3 . A method for manufacturing a high-strength cold-rolled steel sheet, characterized by having: one of claims 1 to 12 a flat steel embryo consisting of heating in a temperature of 1 800 to 1 350 ° C; to make the above-mentioned heated flat steel embryo, (A r3 metamorphosis point - 2 0 ) to (A r3 metamorphic point + a step of forming a hot-rolled steel sheet by hot rolling at a finishing rolling temperature of 10.5; and a step of winding the hot-rolled steel sheet to satisfy a coiling temperature CT of the following formula (5) or (6); a step of cold-rolling the hot-rolled steel sheet after the coiling at a rolling reduction ratio of 50 to 90% to form a cold-rolled steel sheet; and continuously annealing the cold-rolled steel sheet at 750 to 870 ° C or at 600 The step of closed-box annealing to 750 °C; 480 SCTS 580 + 0· 17/{([Ti] + 0. 08x[sol. Α1])χ[Ρ]} ”·(5) 480 ^CT^ 580 + 0. 17/{(0. 6x[Nb] + [Ti ] + 0. 08x[sol. A1 ] )χ[Ρ]} --(6) where [M] represents the content of the element M (quality) %). 24 326\main file\94\94105020\94105020 (replace)-1