KR20150075332A

KR20150075332A - High strength lightweight triple clad steel sheet having excellent stiffness and corrosion resistance properties

Info

Publication number: KR20150075332A
Application number: KR1020130163387A
Authority: KR
Inventors: 조원태; 진광근; 송태진; 전선호; 김성규; 김태호
Original assignee: 주식회사 포스코
Priority date: 2013-12-25
Filing date: 2013-12-25
Publication date: 2015-07-03

Abstract

The present invention relates to a high-strength lightweight triplex clad steel sheet having excellent rigidity, excellent dent resistance, and excellent corrosion resistance; and a manufacturing method thereof. An embodiment of the present invention is composed of a high-manganese steel sheet comprising: 0.01-1.0 wt% of C, 8-30 wt% of Mn, 0.01-3.0 wt% of Al, 0.01-3.0 wt% of Si, 0.1 wt% or less of P, 0.02 wt% or less of S, 0.1 wt% or less of N, and the remainder consisting of Fe and inevitable impurities; and aluminum-based plates formed on both sides of the high-manganese steel sheet. The thickness of the high-manganese steel sheet is 0.1-1.0 mm; the thickness of the aluminum-based plate is 0.1-1.5 mm; the total thickness of the clad steel sheet is 0.7-2.5 mm; and the rigidity of the triplex clad steel sheet is 40 GPa·mm^3 or higher. The high-strength lightweight triplex clad steel sheet of the present invention is light and is capable of remarkably reducing a weight of a product when compared to an existing clad material by obtaining excellent rigidity, strength, and ductility; thereby being desirably applied to vehicle components required to be lightweight. In addition, the present invention is capable of remarkably improving mechanical properties of an exterior panel of a vehicle such as a door, a hood, and an exterior material for a trunk cover currently manufactured of aluminum.

Description

TECHNICAL FIELD [0001] The present invention relates to a high strength lightweight triple clad steel sheet excellent in rigidity and corrosion resistance, and a method of manufacturing the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a high strength and lightweight triple clad steel sheet excellent in rigidity and corrosion resistance and a method of manufacturing the same. More particularly, the present invention relates to a high strength, lightweight triple clad steel sheet for automobiles which can be used for exterior panels and inner plate structural parts such as doors, hoods, trunks, A clad steel sheet and a manufacturing method thereof.

BACKGROUND ART In recent years, in the automobile manufacturing industry, in order to reduce carbon dioxide in exhaust gas in response to environmental regulations, to reduce fuel consumption of fossil fuel cars and to reduce battery consumption of electric vehicles, weight reduction of automobile bodies is continuously being promoted. Particularly, in the case of parts such as doors, hoods, and trunks, which can not be expected to be lighter due to the application of the existing automotive steel sheet, automobile manufacturers can use aluminum, plastic, magnesium There is an increasing tendency to adopt such non-ferrous lightweight materials.

However, these non-ferrous lightweight materials are expensive, and paintability and mechanical properties are not enough to be applied to automotive steel sheets, so that there is a disadvantage that it is necessary to develop new alternative technologies. Particularly, since aluminum is light and excellent in corrosion resistance, its application range has been expanded. However, there is a real problem that it is difficult to substitute steel for use as an automobile material because of low strength and securing workability for part processing.

On the other hand, as a method of reducing the weight of automotive parts using a thin steel plate, there are a method of adding P-doped low carbon steel, Bake Hardenable steel, and Duel Phase Steel (DP steel) There is a method of reducing the weight of parts by designing to reduce the thickness of parts using high strength steel sheets. However, if the thickness of the steel sheet becomes excessively thin, there arises a problem that the part rigidity is lowered, so that the thickness can not be lowered unlimitedly. Therefore, there is a limitation in reducing the thickness of the steel sheet to reduce the parts weight.

On the other hand, clad steel sheets having various thicknesses and physical properties unlike panel high strength steel sheets are also used as automobiles, ships, or multifunctional home appliances. The clad steel sheet is formed by laminating various existing steel materials or nonferrous light-weight materials by various heat treatment and rolling methods, and imparts new properties and properties to the products. When the clad steel sheet is used as an automobile thin plate material, it is possible to produce a product having excellent physical properties and characteristics which can not be realized by conventional steel production methods. Particularly in light of the lightness and securing of rigidity mentioned above, it is believed that the lamination of steel and nonferrous lightweight materials can provide a new answer to the weight reduction of steel parts, which have the problem of securing rigidity.

However, since such a clad steel sheet has a lower elongation than a nonferrous material, there is a limitation in using a soft steel sheet having a high elongation, which limits the strength of the material. Generally, except for extremely low carbon steels, automobile steel plates have a lower elongation rate as the steel sheet is thinned, and steels having a high elongation at 0.2 to 0.6 mm in thickness are not included in high strength steels. There is no special alternative to the production of high strength clad steel sheets for automobiles.

In addition, since the characteristics of aluminum in corrosion resistance is very superior to that of steel, the application of pure aluminum aluminum plate is increasing to secure lighter weight and corrosion resistance, but aluminum alloy has a disadvantage that it is difficult to secure excellent mechanical properties.

Therefore, in automobile parts using steel plates, the effect of weight reduction is higher than that of high-strength steel plates which are limited to be made into a piece, and at the same time, high mechanical properties are utilized while utilizing corrosion characteristics such as aluminum, Therefore, it is necessary to develop steel plates for automobiles with low manufacturing cost.

The present invention relates to a high strength and lightweight triple clad steel sheet having excellent rigidity, strength, workability and corrosion resistance, and capable of maximizing the weight reduction effect of parts by securing a light weight effect of aluminum level, .

An embodiment of the present invention is a steel sheet comprising 0.01 to 1.0% of C, 8 to 30% of Mn, 0.01 to 3.0% of Al, 0.01 to 3.0% of Si, 0.1 to 3.0% of P, , N: 0.1% or less, the balance Fe and unavoidable impurities; And an aluminum-based plate material provided on both sides of the high-manganese steel plate, wherein the high-manganese steel plate has a thickness of 0.1 to 1.0 mm, the aluminum-based plate has a thickness of 0.1 to 1.5 mm, A high strength and lightweight triple clad steel sheet having rigidity of 40 GPa · mm ³ or more and excellent in rigidity and corrosion resistance is provided.

In another embodiment of the present invention, there is provided a steel sheet comprising, by weight%, 0.01 to 1.0% of C, 8 to 30% of Mn, 0.01 to 3.0% of Al, 0.01 to 3.0% of Si, 0.1% , N: 0.1% or less, the balance Fe, and unavoidable impurities to obtain a laminate by providing an aluminum-based plate on both sides of the high manganese steel sheet; Heating the laminate to 200 to 600 占 폚 in a reducing atmosphere; And a step of hot-rolling the heated laminate at a reduction ratio of 1 to 10% to obtain a clad steel sheet. The present invention also provides a method of manufacturing a high strength and lightweight triple clad steel sheet excellent in rigidity and corrosion resistance.

The lightweight clad steel sheet of the present invention is not only light but also has excellent strength and ductility so that the product weight can be remarkably reduced as compared with conventional clad materials and can be suitably applied to automobile parts which are required to be light in weight. , The trunk lid, and the like, can be remarkably improved. Further, since the aluminum-based plate material is provided on the outside, excellent resistance against corrosion caused by the external environment can be secured.

1 is a photograph of a surface of a specimen of Inventive Example 1 observed.
2 is a photograph of the surface of the specimen of Comparative Example 1. FIG.

Hereinafter, the present invention will be described.

First, the alloy composition of the high-strength steel sheet according to the present invention will be described.

C: 0.01 to 1.0 wt%

C is an element that increases the austenite stabilization and stacking fault energy. For the above effect, it is preferable that the C is contained in an amount of 0.01 wt% or more. On the other hand, if it exceeds 1.0% by weight, carbide formation is facilitated in the heat treatment process, thereby providing a place where cracking of hydrogen embrittlement starts, and the delayed fracture characteristic is lowered and the lamination defect energy is excessively increased, The strength is decreased and the elongation rate is lowered. Therefore, it is preferable that the C is in the range of 0.01 to 1.0 wt%.

Mn: 8 to 30 wt%

Mn is an element essential for stably securing the austenite structure and is an element for increasing the stacking defect energy. When the Mn content is less than 8 wt%, martensite deteriorating the formability is formed and the strength is increased, but the ductility is rapidly decreased, the stacking defect energy is lowered, and a part of the austenite is easily transformed into epsilon (?) Martensite Therefore, it is difficult to secure excellent mechanical properties. On the other hand, when the content of Mn exceeds 30 wt%, the production cost due to a large amount of manganese is increased and the slab crack is caused by the increase of the P content in the steel. In addition, as the content of Mn increases, internal calculation of the slab is excessively performed during reheating of the slab, which may cause oxide defects on the surface of the steel sheet, thereby deteriorating the surface characteristics of the steel during hot dip galvanizing. Therefore, the content of Mn is in the range of 8 to 30% .

Al: 0.01 to 3.0 wt%

Al is usually added for deoxidation of steel, but in the present invention, it can be added for improving ductility and delayed fracture. Although Al is a stabilizing element in the ferrite phase, it increases the stacking fault energy at the slip surface of the steel, thereby suppressing the formation of epsilon (ε) martensite phase to improve ductility and resistance to delayed fracture. Also, Al suppresses the formation of epsilon (ε) martensite phase even in the case of low manganese addition, thus contributing to minimizing addition amount of manganese and improving workability. For the above effect, the Al is preferably contained in an amount of 0.01 wt% or more. On the other hand, if it exceeds 3.0% by weight, the generation of twin will be suppressed to decrease ductility, the casting will be bad in continuous casting, and the surface will be seriously oxidized during hot rolling, By weight.

Si: 0.01 to 3.0 wt%

Si is a solid solution strengthening element, and it reduces the grain size and increases the yield strength. For this purpose, the Si content is preferably 0.01 wt% or more. However, when the content of Si is more than 3% by weight, silicon oxide is formed on the surface of the steel sheet during hot rolling to deteriorate the pickling property to deteriorate the surface quality of the hot-rolled steel sheet, Si is preferably in the range of 0.01 to 3.0% by weight.

P: not more than 0.1% by weight

P is an element that is inevitably contained in the production of steel, and therefore, it is important to manage the upper limit. If the P content exceeds 0.1% by weight, segregation is induced to reduce the workability of steel. Therefore, in the present invention, the upper limit of P is controlled to 0.1% by weight.

S: not more than 0.02% by weight

S, like P, is an element that is inevitably contained in the manufacture of steel, so it is important to manage the upper limit. If S is more than 0.02 wt%, coarse manganese sulfide (MnS) is formed to cause defects such as flange cracks. Therefore, in the present invention, the upper limit of S is controlled to 0.02 wt%.

N: 0.1 wt% or less

N acts on aluminum in the austenite crystal grains during the solidification process to precipitate fine nitrides to accelerate the generation of twin crystals, thereby improving the strength and ductility of the steel sheet. However, when the content exceeds 0.1% by weight, Precipitates to decrease the hot workability and elongation. Therefore, the N content is preferably 0.1 wt% or less.

Meanwhile, the high manganese steel sheet used in the present invention may further include at least one selected from the group consisting of 0.005 to 0.2% of Sn, 0.005 to 0.2% of Sb and 0.0001 to 0.01% of B.

The Sn, Sb, and B are elements for improving the plating property. For this, Sn and Sb are preferably added in an amount of 0.005% or more, and B is added in an amount of 0.0001% or more. However, when Sn and Sb exceed 0.02% or B exceeds 0.01%, internal oxidation occurs during rolling, which deteriorates the plating performance. Therefore, Sn is 0.005 to 0.2%, Sb is 0.005 to 0.2% B is preferably in the range of 0.0001 to 0.01%.

Further, the high manganese steel sheet of the present invention may further include at least one of 0.005 to 2.0% of Ni and 0.005 to 5.0% of Cr.

Ni: 0.005 to 2.0 wt%

Ni contributes to stabilization of the austenite, which is not only advantageous for improvement of elongation but also contributes effectively to improvement of high temperature ductility. When the content of Ni is less than 0.005% by weight, the effect on high temperature ductility is very small. When the content of Ni is increased, the effect of the delayed fracture and the prevention of slab cracking is shown. However, , The content of Ni is preferably in the range of 0.005 to 2.0% by weight.

Cr: 0.005 to 5.0 wt%

Cr reacts with external oxygen during the hot rolling or annealing operation to preferentially form a Cr-based oxide film (Cr ₂ O ₃ ) with a thickness of 20 to 50 μm on the surface of the steel sheet to prevent Mn and Si contained in the steel from leaching into the surface layer Thereby contributing to the stabilization of the surface texture and improving the surface properties of the plating. If the amount of Cr is less than 0.005 wt%, the effect is insignificant. If the Cr content exceeds 5.0 wt%, Cr carbide is formed to deteriorate workability and delayed fracture characteristics. Therefore, the Cr content is in the range of 0.005 to 5.0 wt% .

In addition, the high manganese steel sheet of the present invention may further comprise at least one selected from the group consisting of 0.005 to 0.5% of Ti, 0.005 to 0.5% of Nb, 0.005 to 0.5% of V and 0.005 to 1% of W .

Ti: 0.005-0.5 wt%

Ti is a strong carbide-forming element that forms a carbide by bonding with carbon. The carbide is an element effective in refining crystal grains by inhibiting grain growth. Also, when the boron compound is added in combination, a high-temperature compound is formed in the columnar phase boundary to prevent grain boundary cracking. If the amount of Ti is less than 0.005% by weight, the above effect is difficult to expect. If the amount of Ti is more than 0.5% by weight, excess Ti is segregated in grain boundaries to cause intergranular embrittlement or excessively coarsening of the precipitated phase, The Ti content is preferably in the range of 0.005 to 0.5% by weight.

Nb: 0.005-0.5 wt%

Nb is a carbide-forming element that combines with carbon to form carbide, and is an effective element for increasing the strength and refining the grain. Since Nb forms a precipitation phase at a temperature lower than Ti, the crystal grain size is miniaturized and precipitation strengthening effect by precipitation phase formation is large. When the content of Nb is less than 0.005 wt%, the effect is insignificant. When the content of Nb exceeds 0.5 wt%, excessive Nb segregates in grain boundaries to cause intergranular embrittlement or excessively coarsening of the precipitated phase, And the rolling load is increased by delaying the recrystallization in the hot rolling step, it is preferable that the Nb is in the range of 0.005 to 0.5 wt%.

0.005 to 0.5% by weight of V and 0.005 to 1% by weight of W,

V and W are elements which form carbonitride by combining with C and N, such as Ti. In the present invention, since a fine precipitate phase is formed at a low temperature, the precipitation strengthening effect is large and plays an important role in securing austenite. When the content of V and W is less than 0.005% by weight, the above effect is insignificant. When V is 0.5% by weight and W is more than 1.0% by weight, the precipitation phase becomes excessively coarse, , It is preferable that V is 0.005 to 0.5 wt% and W is 0.005 to 1.0 wt% because it causes hot brittleness.

The high manganese steel sheet used in the present invention is preferably a TWIP steel having austenitic single phase structure. By using the TWIP phenomenon of the austenite structure, it is possible to effectively secure high strength and high elongation. In the case of the conventional clad steel sheet, the elongation at the time of increasing the strength is lowered, and the strength and elongation (TS x El) of the clad steel sheet applied are only 20,000 MPa%. However, the high manganese steel sheet has a tensile strength of 600 to 1000 MPa When it is applied to the clad steel sheet of the present invention having an elongation of 30% or more, the strength x elongation is as high as 60,000 MPa%, which makes it possible to secure high strength and high elongation which are difficult to secure in the past.

The clad steel sheet of the present invention is provided with both sides of the high manganese steel sheet as described above with an aluminum-based plate material having a low specific gravity and excellent corrosion resistance. The aluminum-based plate material is provided with an aluminum oxide film on the surface thereof and can impart excellent corrosion resistance to the clad steel plate. On the other hand, in the present invention, since all types of aluminum-based plate materials can be used, the kind of the aluminum-based plate material is not particularly limited. However, in order to prevent defects such as scratches, a 6000- or 7000-series aluminum-based plate material having relatively high strength can be preferably applied to the present invention.

On the other hand, the high-manganese steel sheet constituting the clad steel sheet of the present invention preferably has a thickness of 0.1 to 1.0 mm and a thickness of the aluminum-based plate of 0.1 to 1.0 mm. If the thickness of the high manganese steel sheet is less than 0.1 mm or the thickness of the aluminum manganese sheet exceeds 1.0 mm, sufficient strength, ductility and rigidity can not be ensured. If the thickness of the high manganese steel sheet exceeds 1.0 mm, The thickness can not be effectively reduced when the thickness is less than 0.1 mm. The total thickness of the clad steel sheet of the present invention is preferably 0.7 to 2.5 mm. When the thickness is less than 0.7 mm, sufficient rigidity can not be secured. When the thickness is more than 2.5 mm, the clad steel sheet is used for automobile parts It is difficult to carry out the present invention.

The triple-structure clad steel sheet of the present invention, which is provided as described above, can have a rigidity of 40 GPa · mm ³ or more and can be suitably applied to automotive parts requiring excellent mechanical properties. On the other hand, the stiffness can be calculated by the following relational expression 1, and the following elastic modulus means a value obtained by dividing the inherent elastic modulus of each of the high manganese steel sheet and the aluminum-based sheet material by the volume ratio as applied to the clad steel sheet.

[Relational expression 1] = (elastic modulus) x (thickness) ³

In addition, the clad steel sheet of the present invention can be suitably applied to parts for automobiles which require light weight and excellent mechanical properties due to a density of 5.5 g / cm ³ or less, a tensile strength of 490 MPa or more, a yield strength of 330 MPa or more and an elongation of 20% have.

Hereinafter, the production method of the present invention will be described.

First, an aluminum-based plate material is provided on both sides of a high manganese steel sheet having the above-described alloy composition to obtain a laminate.

Thereafter, the laminate is heated to 200 to 600 占 폚 in a reducing atmosphere. When the heating temperature is lower than 200 ° C, the high manganese steel sheet and the aluminum plate can not be joined together. If the heating temperature is higher than 600 ° C, aluminum is melted or melted to cause melting of aluminum. Meanwhile, the reducing atmosphere may be formed using a reducing gas commonly used in the related art. Accordingly, the type and composition of the reducing atmosphere gas are not particularly limited in the present invention.

Thereafter, the heated laminate is hot-rolled at a reduction rate of 1 to 10% to obtain a hot-rolled clad steel sheet. Through the application of the above-mentioned reduction ratio, an additional effect of increasing the strength due to the high work hardening rate of the additional TIWP steel can be obtained. However, if the reduction rate is less than 1%, the above effects can not be sufficiently obtained and the production of the hot-rolled clad steel sheet may be difficult. The higher the reduction ratio, the better the effect to be obtained by the present invention, but it is difficult to exceed 10% due to limitations in the manufacturing facility.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only illustrative of the present invention in more detail and do not limit the scope of the present invention.

(Example)

The aluminum plate materials as shown in Table 3 were provided on both sides of the high manganese TWIP steel having the alloy composition shown in the following Table 1 to obtain a laminate. The laminate was heated to 350 캜 in a reducing atmosphere, 3 to obtain a clad steel sheet. The thus obtained clad steel sheet was measured for mechanical properties and corrosion resistance, and the results are shown in Tables 3 and 4 below. On the other hand, the mechanical properties of the high manganese steel sheet and the aluminum-based plate applied to the clad steel sheet were as shown in Table 2 below, and the weight reduction ratio was calculated based on Comparative Example 1. On the other hand, the corrosion resistance evaluation was performed by confirming whether or not corrosion was caused by exposure to salt water spray for 120 hours.

division Alloy composition (% by weight) C Mn Al Si P S N Grade 1 0.5 15 0.01 0.5 0.015 0.001 0.01 Gangjong 2 0.8 20 1.2 0.5 0.015 0.001 0.01

division High manganese steel plate division Aluminum-based sheet material Tensile Strength (MPa) Yield strength (MPa) Elongation (%) Tensile Strength (MPa) Yield strength (MPa) Elongation (%) Grade 1 836 454 50 Plate 1 524 461 11 Gangjong 2 967 647 44 Plate 2 260 118 22 Plate 3 186 78 20 Plate 4 137 132 10

division Applicable material Reduction rate
(%) Thickness (mm) The tensile strength
(MPa) Yield strength
(MPa) Elongation
(%) High manganese steel plate Aluminum-based sheet material Total thickness Comparative Example 1 Grade 1 0 0.4 - 0.8 836 454 50 Comparative Example 2 Grade 1+ Plate 1 3 0.2 0.2 0.6 480 270 31 Inventory 1 Gangjong 2 + Plate 2 4 0.38 0.2 0.78 634 402 33 Inventory 2 Grade 2 + Plate 3 3 0.6 0.4 1.4 550 380 29 Inventory 3 Steel 2+ Plate 4 3 0.6 0.4 0.4 528 401 23

division Elastic modulus (GPa) Rigidity (GPa · mm ³ ) Density (g / cm ³⁾ Lightweighting rate (%) Corrosion resistance Comparative Example 1 185 12 7.5 0 corrosion Comparative Example 2 110 24 4.3 43 Good Inventory 1 127 60 5.0 33 Good Inventory 2 120 330 4.8 37 Good Inventory 3 120 330 4.8 37 Good

As can be seen from Tables 1 to 4, in Examples 1 to 3 satisfying the conditions of the present invention, a rigidity of 40 GPa · mm ³ or more, a density of 5.5 g / cm ³ or less, a tensile strength of 490 MPa or more, It can be confirmed that the yield strength and elongation of 20% or more are secured and excellent corrosion resistance is secured.

This level of physical properties shows that the strength and elongation are not significantly lowered compared with Comparative Example 1 which is a TWIP steel single steel, but the weight is considerably increased.

On the other hand, in the case of Comparative Example 2 which does not satisfy the cladding steel sheet thickness range of the present invention, it can be seen that the rigidity of 40 GPa-mm ³ or more can not be secured.

Figs. 1 and 2 are photographs of the surfaces of specimens of Inventive Example 1 and Comparative Example 1, respectively. 1 and 2, it can be seen that the clad steel sheet of Inventive Example 1 was not corroded and had excellent surface quality, but in Comparative Example 1, it was confirmed that the corrosion was severe.

Claims

0.01 to 3.0% of Si, 0.1% or less of P, 0.02% or less of S, 0.1% or less of N, 0.01 to 3.0% of Cr, 0.01 to 1.0% of C, A high manganese steel plate containing the remainder Fe and unavoidable impurities; And an aluminum-based plate material provided on both sides of the high-manganese steel sheet,
The high manganese steel sheet has a thickness of 0.1 to 1.0 mm, the aluminum-based sheet material has a thickness of 0.1 to 1.0 mm,
The total thickness of 0.7 ~ 2.5mm and, 40GPa · mm ³ or more rigid having rigidity and corrosion resistance of the clad sheet having excellent high-strength light-weight 3.

The method according to claim 1,
Wherein the high-manganese steel sheet further comprises at least one member selected from the group consisting of 0.005 to 0.2% of Sn, 0.005 to 0.2% of Sb, and 0.0001 to 0.01% of B and having a high rigidity and a high corrosion- .

The method according to claim 1,
Wherein the high-manganese steel sheet further comprises at least one of 0.005 to 2.0% of Ni and 0.005 to 5.0% of Cr, and further has excellent rigidity and corrosion resistance.

The method according to claim 1,
The high manganese steel sheet preferably has a rigidity and corrosion resistance further comprising at least one selected from the group consisting of 0.005 to 0.5% of Ti, 0.005 to 0.5% of Nb, 0.005 to 0.5% of V and 0.005 to 1% of W Excellent high strength lightweight triple clad steel.

The method according to claim 1,
The high manganese steel sheet has austenite single phase structure and is excellent in rigidity and corrosion resistance.

The method according to claim 1,
The high-manganese steel sheet has a tensile strength of 600 to 1000 MPa and an elongation of 30% or more, and is excellent in rigidity and corrosion resistance.

The method according to claim 1,
The clad steel sheet has a density of 5.5 g / cm ³ or less, a tensile strength of 490 MPa or more, a yield strength of 330 MPa or more, and an elongation of 20% or more. The clad steel sheet is excellent in rigidity and corrosion resistance.

0.01 to 3.0% of Si, 0.1% or less of P, 0.02% or less of S, 0.1% or less of N, 0.01 to 3.0% of Cr, 0.01 to 1.0% of C, Providing an aluminum-based plate material on both sides of a high manganese steel sheet containing the remainder Fe and unavoidable impurities to obtain a laminate;
Heating the laminate to 200 to 600 占 폚 in a reducing atmosphere; And
And a step of hot-rolling the heated laminate at a reduction ratio of 1 to 10% to obtain a clad steel sheet. The method for producing a high strength and lightweight triple-clad steel sheet excellent in rigidity and corrosion resistance.

The method of claim 8,
Wherein the high-manganese steel sheet further comprises at least one member selected from the group consisting of 0.005 to 0.2% of Sn, 0.005 to 0.2% of Sb, and 0.0001 to 0.01% of B and having a high rigidity and a high corrosion- &Lt; / RTI >

The method of claim 8,
Wherein the high manganese steel sheet further comprises at least one of 0.005% to 2.0% of Ni and 0.005% to 5.0% of Cr, and has excellent rigidity and corrosion resistance.

The method of claim 8,
The high manganese steel sheet preferably has a rigidity and corrosion resistance further comprising at least one selected from the group consisting of 0.005 to 0.5% of Ti, 0.005 to 0.5% of Nb, 0.005 to 0.5% of V and 0.005 to 1% of W (EN) METHOD FOR PREPARING EXCELLENT HIGH - STRENGTH AND LIGHT -