JP2002030384A - Corrosion-resistant steel plate for fuel tank excellent in secondary workability and press workability and method for producing the same - Google Patents

Abstract

(57) [Summary] (Corrected) [PROBLEMS] To provide a rustproof steel plate having excellent press workability as a rustproof steel plate for a fuel tank of an automobile, and a method of manufacturing the same. SOLUTION: In mass%, C: 0.01% or less, Si;
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two of Ti and Nb are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, B: 0.0001 to 0.00
5%, in the case of Ti and Nb added steel, one of Cu, Cr and Ni
0.1% or more and 0.5% or less in total of two or more species,
In addition, Ti, Nb, V, Mo, and Zr-added steel and V, Mo,
In the case of Zr-added steel, one or more of Cu, Cr and Ni are contained in a total of 0.002% or more and 0.5% or less,
The rest is on the surface of the steel plate consisting of Fe and unavoidable impurities,
A rust-preventive steel plate for a fuel tank having a coating layer containing 2 to 13% by mass of Si in mass% and a balance of 50% or more of an Al-based chemical component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rustproof steel plate having excellent press workability as a steel plate for a fuel tank of an automobile, and a method for producing the same.

[0002]

2. Description of the Related Art A fuel tank of an automobile is usually designed last in accordance with the design of a vehicle body, and its shape tends to be more and more complicated in recent years. Further, since the fuel tank is an important security part of an automobile, the material used for the fuel tank is required to have not only excellent deep drawing properties but also no cracking due to impact after molding. In addition, it is also important that the material be free from corrosion products that lead to perforated corrosion and filter clogging, be easily and stably welded, and be excellent in the airtightness of the welded portion.

[0003] As a material having these various characteristics, a Pb-Sn alloy-plated steel sheet (Japanese Patent Publication No. 57-61833), which is conventionally called a turn sheet, has been mainly used. This material has stable chemical properties with respect to gasoline, and has excellent press workability due to excellent plating lubricity. In addition, a steel sheet obtained by subjecting a galvanized steel sheet to a thick chromate treatment is also used. Although not as good as a Pb-Sn alloy, it also has excellent workability and corrosion resistance. However, in recent years, materials that do not use Pb have been sought from the viewpoint of load on the environment.

One of the candidate materials for automotive fuel tank materials not using Pb is an aluminum (Al-Si) plated steel sheet. Since aluminum has a stable oxide film formed on its surface, it has good corrosion resistance to organic acids generated when gasoline, alcohol, gasoline and the like are deteriorated. However, there are some problems when using an aluminum-plated steel sheet as a fuel tank material. One of these is workability. Aluminum-plated steel sheets are very hard Fe-Al-Si intermetallic compound layers (hereinafter referred to as alloy layers) generated at the interface between the coating layer and the steel sheets. It is easy to cause plating peeling and plating cracks. To solve this problem, the present inventors set the plating conditions as disclosed in JP-A-9-5 / 95.
Japanese Patent No. 3166 discloses that the problem can be solved by cooling rate after plating and reheating.

[0005] However, there has been almost no knowledge about the stripping of aluminum-plated steel sheets and the generation of cracks in the plating in terms of steel components. Further, as described above, since the automobile fuel tank is an important security part, it is required to have impact resistance after molding. This property is called the secondary workability because it is the processing property after press forming (primary forming). This 2
Japanese Patent Application Laid-Open No.
However, there is no knowledge about the relationship with a plating alloy layer as an automotive fuel tank material.

[0006]

Means for Solving the Problems The present inventors have studied the effect of the steel composition on the peeling properties of the aluminum-plated steel sheet and the occurrence of cracks in the plating. As a result, the optimization of the steel composition, that is, the Cu, Ni, Cr It has been found that the occurrence of cracks in plating due to the properties of the alloy layer is improved and the secondary workability is improved by restricting the addition of the composite and the other elements contained in trace amounts. Although the exact cause is unknown, it is considered as follows. That is, Cu, Ni, Cr and other trace elements are concentrated on the surface during slab reheating in hot rolling or during the annealing step. To grow the alloy layer, Fe
The diffusion behavior of Cu into the plating layer is important, but Cu, Ni, Cr and other trace elements contained on the surface are considered to be barriers to the diffusion of Fe into the plating layer, and these barriers are present. Thus, it is considered that the growth of the alloy layer in the plating step is optimized.

That is, when there is no barrier, a large amount of Fe diffuses into the plating layer and the alloy layer grows excessively,
It is estimated that cracks are likely to occur in the alloy layer after press forming. This crack is the impact resistance after molding.
It is considered that the next workability is deteriorated. Also, when an excessive barrier is present, it is considered that the growth of the alloy layer is excessively suppressed, the adhesion of the plating is reduced, and the corrosion resistance after press molding is reduced. Therefore, it is necessary to limit Cu, Ni, Cr and other trace elements to achieve both the secondary workability and the press workability.

[0008] In addition, for the steel plate for the fuel tank, a steel in which solid solution C and N are fixed by adding a carbonitride forming element such as Ti and Nb in order to obtain deep drawability is used. When V, Mo, or Zr, which has a lower carbonitride forming ability than Ti or Nb, is added, solute V, Mo, and Zr are likely to remain, so that these elements are slab-reheated during hot rolling or during annealing. Examination of the surface enrichment behavior in the process revealed that it enriched on the surface in the same manner as Cu, Ni and Cr. Therefore, the above Cu, Ni,
It is conceivable that the effect of improving the secondary workability by Cr is promoted and works effectively even with a small amount of addition.

The gist of the present invention is as follows: (1) In mass%, C: 0.01% or less, Si: 0.2%
Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less, Ti, N
One or two kinds of b in total (C + N) in an atomic equivalent or more and 0.5% or less, B: 0.0001 to 0.005%, C
0.1% in total of one or more of u, Cr and Ni
0.5% or less, the balance being on the surface of a steel sheet composed of Fe and unavoidable impurities, Si: 2 to 13% by mass%.
A rust-preventive steel sheet for fuel tanks having excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component having an Al content of 50% or more.

(2) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
% Or less, acid-soluble Al: 0.1% or less, N: 0.01% or less, and one or two of Ti and Nb in total at least the atomic equivalent of (C + N) and 0.5% or less, B: 0.0001-0.
005%, one or more of Cu, Cr and Ni in total of 0.1% or more and 0.5% or less, and Hf, Ta,
W, Tc, Re, Ru, Os, Co, Rh, Ir, P
d, Pt, Ag, Au, Zn, Cd, Hg, Ge, S
One or more of n, Pb, As, Sb, Bi, Se, Te, and Po contain 0.02% or less by mass%, with the balance being Fe and unavoidable impurities. Secondary workability and press workability, characterized by having a coating layer composed of an Al-based chemical component containing 2 to 13% of Si by mass% and the remaining 50% or more of Al. Excellent rust-proof steel plate for fuel tanks.

(3) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
% Or less, acid-soluble Al: 0.1% or less, N: 0.01% or less, and one or two of Ti and Nb in total at least the atomic equivalent of (C + N) and 0.5% or less, B: 0.0001-0.
005%, containing one or more of Cu, Cr, and Ni in total of 0.1% or more and 0.5% or less;
The sum of one or more of Y and REM is 0.1% by mass.
Al-based chemical component containing not more than 01%, the balance being Si: 2 to 13% by mass on the surface of a steel sheet consisting of Fe and unavoidable impurities, and the balance having an Al content of 50% or more. A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of:

(4) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
% Or less, acid-soluble Al: 0.1% or less, N: 0.01% or less, and one or two of Ti and Nb in total at least the atomic equivalent of (C + N) and 0.5% or less, B: 0.0001-0.
005%, one or more of Cu, Cr and Ni in total of 0.1% or more and 0.5% or less, and Hf, Ta,
W, Tc, Re, Ru, Os, Co, Rh, Ir, P
d, Pt, Ag, Au, Zn, Cd, Hg, Ge, S
n, Pb, As, Sb, Bi, Se, Te, Po, or a sum of at least two of them in mass% is 0.02% or less;
The sum of one or more of g, Ca, Y, and REM contains 0.01% or less by mass%, and the balance is expressed by Si: 2% by mass on the surface of a steel sheet composed of Fe and unavoidable impurities. 1
3%, the balance being Al having an Al content of 50% or more
A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of a system chemical component.

(5) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, one or two of Ti and Nb and one of V, Mo, and Zr
At least 0.5% or less of the atomic equivalent of (C + N) in total of two or more species, B: 0.0001 to 0.005%, C
at least one of u, Cr and Ni
2% or more and 0.5% or less, the balance being on the surface of a steel sheet composed of Fe and inevitable impurities, Si: 2 to 1 by mass%.
3%, the balance being Al having an Al content of 50% or more
A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of a system chemical component.

(6) In mass%, C: 0.01% or less,
Si: 0.2% or less, Mn: less than 0.6%, P: 0.0
4% or less, acid-soluble Al: 0.1% or less, N: 0.01%
Hereinafter, one or two or more of Ti and Nb and one or two or more of V, Mo, and Zr are used in total, and the atomic equivalent of (C + N) amount is 0.5% or more and B: 0.0001 to 0.005. %, C
at least one of u, Cr and Ni
Hf, Ta, W, T
c, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
The sum of at least one of b, As, Sb, Bi, Se, Te, and Po contains 0.02% or less by mass%, and the balance is expressed on the surface of the steel sheet composed of Fe and unavoidable impurities. % Of Si: 2 to 13%, with the balance having a coating layer composed of an Al-based chemical component having an Al content of 50% or more, which is excellent in secondary workability and press workability. Rustproof steel plate for fuel tank.

(7) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, one or two of Ti and Nb and one of V, Mo, and Zr
At least 0.5% or less of the atomic equivalent of (C + N) in total of two or more species, B: 0.0001 to 0.005%, C
at least one of u, Cr and Ni
Mg, Ca, Y, RE containing 2% or more and 0.5% or less
One or more of M contains 0.01% or less by mass% of Si, and the balance contains Si: 2 to 13% by mass on the surface of the steel sheet composed of Fe and unavoidable impurities; A rust-preventive steel sheet for a fuel tank having excellent secondary workability and press workability, characterized in that the remainder has a coating layer made of an Al-based chemical component having an Al content of 50% or more.

(8) In mass%, C: 0.01% or less,
Si: 0.2% or less, Mn: less than 0.6%, P: 0.0
4% or less, acid-soluble Al: 0.1% or less, N: 0.01%
Hereinafter, one or two or more of Ti and Nb and one or two or more of V, Mo, and Zr are used in total, and the atomic equivalent of (C + N) amount is 0.5% or more and B: 0.0001 to 0.005. %, C
at least one of u, Cr and Ni
Hf, Ta, W, T
c, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
one or more of b, As, Sb, Bi, Se, Te, and Po is 0.02% or less by mass%, Mg, C
The sum of one or more of a, Y, and REM contains 0.01% or less by mass%, and the balance is Si: 2 to 13% by mass on the surface of a steel sheet composed of Fe and unavoidable impurities. A rust-preventive steel sheet for fuel tanks having excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component having an Al content of 50% or more.

(9) In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, and one or more of V, Mo and Zr in total (C
+ N) not less than the atomic equivalent of the amount and not more than 0.5%, B: 0.000
1 to 0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% to 0.5%,
The rest is on the surface of the steel plate consisting of Fe and unavoidable impurities,
Excellent secondary workability and press workability, characterized by having a coating layer containing 2 to 13% by mass of Si by mass% and the balance having an Al content of 50% or more and made of an Al-based chemical component. Anti-corrosion steel plate for fuel tanks.

(10) In mass%, C: 0.01% or less,
Si: 0.2% or less, Mn: less than 0.6%, P: 0.0
4% or less, acid-soluble Al: 0.1% or less, N: 0.01%
In the following, one or more of V, Mo, and Zr are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, and B: 0.0
001-0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% or more and 0.5% or less, and Hf, Ta, W, Tc, Re, Ru, Os, Co,
Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, H
g, Ge, Sn, Pb, As, Sb, Bi, Se, T
e, the sum of one or more of Po is 0.0% by mass.
Al based chemical component containing 2% to 13% by mass of Si on the surface of a steel sheet containing 2% or less, the balance being Fe and unavoidable impurities, and the balance being 50% or more. A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of:

(11) In mass%, C: 0.01% or less,
Si: 0.2% or less, Mn: less than 0.6%, P: 0.0
4% or less, acid-soluble Al: 0.1% or less, N: 0.01%
Hereinafter, one or two or more of V, Mo, and Zr are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%;
001 to 0.005%, containing one or more of Cu, Cr, Ni in a total of 0.002% to 0.5%, and one or more of Mg, Ca, Y, REM Is 0.01% by mass or less and the balance is Fe and unavoidable impurities.
A fuel tank protection excellent in secondary workability and press workability characterized by having a coating layer containing 2 to 13% and the balance being an Al-based chemical component having an Al content of 50% or more. Rust steel plate.

(12) In mass%, C: 0.01% or less,
Si: 0.2% or less, Mn: less than 0.6%, P: 0.0
4% or less, acid-soluble Al: 0.1% or less, N: 0.01%
In the following, one or more of V, Mo, and Zr are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, and B: 0.0
001-0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% or more and 0.5% or less, and Hf, Ta, W, Tc, Re, Ru, Os, Co,
Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, H
g, Ge, Sn, Pb, As, Sb, Bi, Se, T
e, the sum of one or more of Po is 0.0% by mass.
2% or less, the sum of one or more of Mg, Ca, Y, and REM contains 0.01% or less by mass%, and the balance is F
e and unavoidable impurities, the surface of the steel sheet contains 2 to 13% of Si by mass%, and the balance has an Al content of 50%.
A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component of at least 0.1%.

(13) The steel ingot of the steel component shown in the above (1) to (12) is heated at a temperature of 1000 ° C. or more, then hot-rolled at a temperature of Ar ₃ or more, cooled, and rolled at a temperature of 800 ° C. or less. The hot rolled steel sheet was pickled, cold rolled at a rolling reduction of 50% or more, then heated at a recrystallization temperature or higher in a hot dipping line and cooled after the steel sheet was recrystallized.
The secondary processing is characterized in that, after plating with a chemical component containing an Al-based chemical component having an Al content of 50% or more, the amount of Al is controlled by gas wiping. The present invention relates to a method for producing a rust-preventive steel plate for a fuel tank having excellent heat resistance and press workability.

Hereinafter, the present invention will be described in detail. First, the reasons for limiting the steel components will be described. C: In the present invention, it is necessary that the steel sheet has a deep drawability capable of being processed into a complicated shape such as a fuel tank, and the smaller the C content, the better. If C exceeds 0.01%, the formability is high. , The value% is set as the upper limit. When higher moldability is required, 0.003% or less is desirable. Si: Si has a strong affinity for oxygen, and easily forms a stable oxide film on the surface in a hot-dip aluminum plating process. When the oxide film is formed, the Al-Fe reaction in the plating bath is inhibited, and a plating defect called non-plating is easily formed during aluminum plating. Further, since this element is also an element that hardens the steel sheet, it is preferable that the element is small as the steel sheet requiring high formability as in the present invention, and the content is 0.2% or less.
It is more preferably at most 0.1%.

Mn: Mn is an element effective for increasing the strength of a steel sheet, but the present invention aims at a soft steel sheet, and the smaller the number, the better. If Mn is 0.6% or more, it is difficult to harden the steel to produce a steel sheet with high ductility, so Mn is set to less than 0.6%. Desirably, it is 0.4% or less. P: P is an element that segregates the grain boundary to embrittle the grain boundary, and also an element that inhibits the ductility of the steel sheet. Further, although the reason is not clear, the effect on the secondary workability is great, and when added over 0.04%, the secondary workability is greatly reduced even if B is added. Therefore, in the present invention, it is limited to 0.04% or less. Desirably 0.02%
It is as follows.

Al: Al, like Si, is an element having a high affinity for oxygen and tends to make hot-dip aluminum plating difficult. Further, in order to inhibit the workability of the steel sheet by forming Al ₂ O ₅ -based inclusions, the content is set to 0.1% or less as the acid-soluble Al.
Although the lower limit is not particularly set, it is preferable to add a small amount to suppress the generation of surface flaws due to Ti oxide.
-007% is a preferable addition range. N: For the same reason as for C, it is preferable that N is also small, and the upper limit of N is set to 0.01% from the viewpoint of ensuring moldability.

Ti: Nb is an element for fixing solid solution C and N, and a steel sheet fixing C and N with these elements to substantially eliminate solid solution C and N is known as IF steel. Such IF steel is not only soft but also excellent in deep drawability. In the present invention, Ti and Nb are added for this purpose. It is necessary that the amount added be at least (C + N) atomic equivalents, and this value is the lower limit. If the amount is too large, the effect is saturated, and particularly, Ti is an element that promotes Al-Fe. If the amount is too large, the alloy layer tends to be thick, and the plating adhesion is impaired. Excessive addition lowers the ductility and the press workability. Therefore, the upper limit is set to 0.5%.

V, Mo, and Zr are elements that fix solid solution C and N as well as Ti and Nb, and in order to obtain sufficient deep drawability, the amount of Ti, Nb, V, Mo, and Zr must be ( C +
N) or more. Further, if the amount is too large, the effect is saturated, and excessive addition lowers the ductility and the press workability. Therefore, the upper limit is set to 0.5%. In addition, since these elements concentrate on the surface during heating of the hot-rolled slab or during the annealing step, C
There is an effect of promoting the secondary workability improvement effect by u, Ni, and Cr. B: It is known to improve the secondary workability and fatigue strength when B is subjected to external force again after deep drawing once. To exert this effect, 0.0001% or more is required, and stable performance can be obtained with 0.0003% or more. However, if the added amount is too large, the processability is reduced. Therefore, the upper limit is 0.0050%, desirably 0.00
30%.

Cu, Ni, Cr: These elements are considered to concentrate on the surface of the steel sheet during hot rolling and annealing, and control the diffusion of Fe into the plating layer. When the addition amount of one or more of these elements is 0.1% or less, the barrier effect is poor and the alloy layer grows, so that cracks are likely to occur after press working, and the secondary workability is not improved.
When one or more of V, Mo, and Zr are added as carbonitride forming elements, these elements are concentrated in the surface layer, so that the barrier effect of Cu, Ni, and Cr is increased. Is promoted. For this reason, the secondary workability is improved with an addition amount of 0.002% or more. Further, if added in an amount of 0.5% or more, the barrier effect works excessively, the growth of the alloy layer is excessively suppressed, and the plating adhesion decreases.

Hf, Ta, W, Tc, Re, Ru, O
s, Co, Rh, Ir, Pd, Pt, Ag, Au, Z
n, Cd, Hg, Ge, Sn, Pb, As, Sb, B
i, Se, Te, Po: These elements are also concentrated on the surface of the steel sheet during hot rolling and annealing to become a barrier. When the total of one or more of these elements is 0.02% or more, the above-mentioned barrier effect works excessively, the growth of the alloy layer is excessively suppressed, and the plating adhesion decreases. Other trace elements include:
Mg, Ca, Y, REM as oxide / sulfide forming elements
However, since the ductility to be added excessively decreases, the sum of these elements is set to 0.01% or less.

Next, the reason for limiting the coating layer will be described. The amount of Si added to the plating coating layer is usually about 10% for the purpose of thinning the alloy layer. As described above, the alloy layer formed by hot-dip aluminum plating is very hard and brittle, so that it is likely to be a starting point of destruction, and also impairs the ductility of the steel sheet itself. Even with a normal alloy layer of about 2 to 3 μm, the ductility of the steel sheet is reduced by about 3 points. Therefore, the thinner this alloy layer is, the more advantageous it is for processing. Unless Si is added in an amount of 2% or more, the effect of reducing the alloy layer is small, and if it exceeds 13%, the effect is saturated and, in addition, Si is easily electrochemically used as a cathode. This leads to a reduction in the corrosion resistance of the layer. For this reason, the amount of Si is limited to 2 to 13%.

As another component, Mg may be added from the viewpoint of improving corrosion resistance. At that time, the amount added
20% or less is desirable because dross in the molten aluminum bath increases. It should be noted that Fe and Cr inevitably dissolve from a steel plate, equipment in a plating bath, and the like as impurity elements in the plating layer, and Cu and Cu as impurities in Al metal.
Ni, Ca, Mg, etc. may be present, Fe may contain about 0.5%, and other elements may contain about 0.01 to 0.1%.
The inclusion of these elements does not impair the spirit of the present invention.

Other conditions of the aluminum plating are not particularly limited. As the coating weight increases, corrosion resistance increases, while plating adhesion and weldability tend to decrease. 50g / m ² per side as an automotive fuel tank material requiring strict molding and various welding
It is desirable that the thickness be as follows, and that the thickness be uniform. The thickness of the alloy layer is preferably thin as described above. After plating, chromate treatment for primary rust prevention, annealing treatment for modifying the plating layer, temper rolling for adjusting surface condition and material, resin coating for imparting lubricity and weldability However, in the present invention, these are not particularly limited. However, in order to obtain stable weldability, it is desirable to have a thin organic coating layer of about 0.3 to 1 μm on the outermost surface.

Although the method of manufacturing a hot-dip aluminum-coated steel sheet for a fuel tank having the features of claims 1 to 12 is not impaired by any method, the method of claim 13 is economically advantageous. Method. The reasons for limiting the manufacturing method are described below. Heating temperature of hot rolling is 100
The reason why the temperature is set to 0 ° C. or higher is that if the temperature is not higher than 0 ° C., the deformation resistance in rolling increases, which is uneconomical. A for hot rolling
The reason for the performed at r ₃ above temperature is lower than this at a temperature remained coarse grain and processed grain hot rolled sheet cold rolled - in order to degrade the deep drawability after recrystallization annealing. 800 ° C winding
The reason why the heat treatment is performed at the following temperature is that if the temperature is higher than this temperature, the scale thickness of the hot-rolled coil becomes hot, which is uneconomical in the pickling step. The reason why the cold rolling rate is set to 50% or more is that if the cold rolling rate is less than this, the deep drawability required for press working of the fuel tank cannot be obtained. The reason why the annealing temperature in the hot-dip plating line is equal to or higher than the recrystallization temperature is that if it is lower than this temperature, ductility and deep drawability required for press working of the fuel tank cannot be obtained.

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

EXAMPLES The steels shown in Tables 1 to 7 and 16 to 18 were smelted by ordinary converter-vacuum degassing to obtain slabs, which were then subjected to hot rolling and cold rolling under ordinary conditions. Thus, a cold-rolled steel sheet (sheet thickness 0.8 mm) was obtained. Using this as a material, hot-dip aluminum plating was performed. For the hot-dip aluminum plating, a non-oxidizing furnace-reduction furnace type line was used, and annealing was also performed in this hot-dip plating line. The annealing temperature was 800 to 850 ° C. After plating, plating thickness is about 60 g / m ² on both sides by gas wiping method.
Was adjusted to At this time, the plating temperature was 660 ° C., the plating bath composition was basically Al-2% Fe, and Si was added thereto. The Fe in the bath is supplied from plating equipment or strips in the bath. The performance of the aluminum-plated steel sheet manufactured in this manner as a fuel tank was evaluated. The evaluation items are shown below.

(1) Evaluation of secondary workability Using a hydraulic forming tester, a punch diameter of 40 mmφ, a punch shoulder R5 mm, a die diameter of 42.8 mmφ, and a die shoulder R5 mm
The cup formed with a wrinkle holding force of 1000 kgf and a draw ratio of 2.0 was cooled using a mold of
7 degrees) Put a cup on the punch with 5m from 1m height
g weight was dropped. At that time, evaluation was made based on the temperature at which the brittle crack occurred. [Evaluation criteria] ◎: -120 ° C or less ○: -100 ° C or less △: -70 ° C or less ×: -70 ° C or more-: Molding not possible

(2) Evaluation of press workability and plating adhesion Using a hydraulic molding tester, a punch diameter of 40 mmφ, a punch shoulder R5 mm, a die diameter of 42.8 mmφ, and a die shoulder R5 mm were used.
The limiting drawing ratio (LDR) was determined at a wrinkle holding force of 1000 kgf using the mold described in the above. The evaluation of formability was based on the following index. [Evaluation Criteria] A: L. D. R ≧ 2.2 ○: 2.0 ≦ L. D. R <2.2 Δ: 1.8 ≦ L. D. R <2.0 ×: L. D. R <1.8 At this time, the state of plating peeling when deep drawing was performed at the limit drawing ratio was visually observed, and the plating peeling property was evaluated. [Evaluation criteria] ○: No plating peeling ×: Plating peeling

(3) Evaluation of Corrosion Resistance The corrosion resistance to gasoline was evaluated. The method was as follows. A test solution was poured into a sample obtained by drawing a flat-bottomed cylinder having a flange width of 20 mm, a diameter of 50 mm, and a depth of 25 mm using a hydraulic molding tester, and the sample was covered with glass via a silicon rubber ring.
This was left standing at room temperature for 3 months, and the state of corrosion was visually observed. Test liquid: gasoline + distilled water 10% + formic acid 200 ppm [Evaluation criteria]-: Unable to evaluate because molding is impossible ○: Less than 0.1% of red rust generated △: 0.1 to 5% of red rust generated or white rust generated ×: Red rust occurrence of more than 5% or white rust remarkable

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

[0043]

[Table 7]

[0044]

[Table 8]

With respect to Nos. 1 to 313, liquids of steel components were examined. The experimental results are shown in Tables 2 to 5. Nos. 1 to 47 are the amounts of C, Ti, and Nb that affect the properties of Ti and Nb-added steel.
The effects of the amount, Cu, Cr, Ni amount, and B amount were examined. Table 8 shows the results. At this time, S in the plating bath
The amount of i added was 9.4%. Also, Hf, Ta, W, T
c, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
The sum of b, As, Sb, Bi, Se, Te, and Po is% by mass.
0.005 to 0.019%, Mg, Ca, Y, REM
Was 0.0001 to 0.0099% by mass%. In Nos. 1, 6, and 9, since the amounts of Ti and Nb added were equal to or less than the equivalent of C + N, the moldability was reduced. No5,8,1
In No. 2, since the sum of the added amounts of Ti and Nb exceeded the limit, plating adhesion and formability were reduced.

Nos. 13, 23, 33 and 39 are Cu, C
Since the sum of the added amounts of r and Ni was less than the limit, the secondary workability was not improved. Nos. 22 and 32 are Cu, Cr,
Since the sum of the added amounts of Ni was more than the limit, the plating adhesion was lowered and the corrosion resistance was deteriorated. In Nos. 34 and 40, since the amount of B added was less than the limit, the secondary workability was reduced.
In Nos. 38 and 44, since the amount of B added was more than the limit,
Moldability decreased. Since other experiments were within the scope of the present invention, a hot-dip aluminized steel sheet for a fuel tank having good secondary workability and press workability could be produced.

Nos. 48 to 232 indicate the amounts of C and T that affect the properties of steel to which Ti and Nb are added and to which V, Mo, and Zr are added.
i, Nb, V, Mo, Zr amount, Cu, Cr, Ni amount, B
The effect of volume was considered. Tables 9 to 1 show the results.
It is shown in FIG. At this time, the amount of Si added in the plating bath was 9.4%.
And Also, Hf, Ta, W, Tc, Re, Ru, O
s, Co, Rh, Ir, Pd, Pt, Ag, Au, Z
n, Cd, Hg, Ge, Sn, Pb, As, Sb, B
The sum of i, Se, Te and Po is 0.005 to 0.5% by mass.
019%, and the sum of Mg, Ca, Y, and REM is 0.1% by mass.
0001-0.0099%. No. 111, 11
4, 117, 122, 125 and 128 are Ti, Nb,
Since the addition amounts of V, Mo, and Zr were equal to or less than the equivalent of C + N, the moldability was reduced. No. 50, 53, 56, 59,
62, 65, 68, 78, 81, 84, 87, 90, 9
In No. 3,96, the sum of the amounts of Ti, Nb, V, Mo, and Zr exceeded the limit, so that the plating adhesion and the formability decreased.

No. 141, 151, 161, 171, 1
81, 191, 201, 211, 222 and 228 are C
Since the sum of the added amounts of u, Cr and Ni was less than the limit,
Secondary workability did not improve. No. 150, 160, 1
70, 180, 190, 200, 210 and 220 are C
Since the sum of the added amounts of u, Cr and Ni was more than the limit, the plating adhesion was lowered and the corrosion resistance was deteriorated. No2
In Nos. 21 and 227, since the amount of B added was less than the limit, the secondary workability was reduced. In Nos. 226 and 232, since the amount of B added was more than the limit, the moldability was reduced. Since other experiments were within the scope of the present invention, a hot-dip aluminized steel sheet for a fuel tank having good secondary workability and press workability could be produced.

[0049]

[Table 9]

[0050]

[Table 10]

[0051]

[Table 11]

[0052]

[Table 12]

Nos. 233 to 313 indicate the amounts of C, V, Mo, Zn, Cu, and C that affect the respective properties of V, Mo, and Zr-added steels.
The effects of the amounts of r, Ni and B are examined. Tables 13 and 14 show the results. At this time, the Si in the plating bath
The addition amount was 9.4%. Also, Hf, Ta, W, T
c, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
The sum of b, As, Sb, Bi, Se, Te, and Po is% by mass.
0.005 to 0.019%, Mg, Ca, Y, REM
Was 0.0001 to 0.0099% by mass%. No. 233, 237, 241, 245, 249,
In 253 and 257, since the added amounts of V, Mo, and Zr were equal to or less than the equivalent of C + N, the green formability decreased. No.236,2
40, 244, 248, 252, 256 and 260 are V,
Since the sum of the added amounts of Mo and Zr exceeded the limit, plating adhesion and formability were reduced.

No. 268, 278, 288, 298, 3
In No. 09, the sum of the added amounts of Cu, Cr and Ni was less than the limit, and the secondary workability was not improved. No. 277, 2
In 87, 297, 307, the sum of the added amounts of Cu, Cr, and Ni was more than the limit, so that the plating adhesion was lowered and the corrosion resistance was deteriorated. In No. 308, since the amount of B added was less than the limit, the secondary workability was reduced. In No. 313, since the amount of B added was more than the limit, the moldability was reduced. Since other experiments were within the scope of the present invention, a hot-dip aluminized steel sheet for a fuel tank having good secondary workability and press workability could be produced.

[0055]

[Table 13]

[0056]

[Table 14]

In Nos. 314 to 335, Si in the plating bath
The effect of concentration was studied. Table 15 shows the results. No
Mg was added to 316 and 325 as another component of Al and Si. The experimental results are shown in Tables 6 and 7. Steel C,
The study was performed using AV, HZ, J, BQ, CA, and IP. No. 314, 319, 324, 328, 330, 3
In Nos. 32 and 334, the adhesion of plating was reduced because the Si concentration in the plating bath was lower than the limit. Therefore, the corrosion resistance also decreased. No. 318, 323, 327, 329, 33
In 1,333 and 335, the corrosion resistance was lowered because the Si concentration in the plating bath was higher than the limit. In other experiments, the plating adhesion and the corrosion resistance were good, and an aluminum-plated steel sheet for a fuel tank having good secondary workability and press workability could be produced.

[0058]

[Table 15]

For Nos. 336 to 426, the effects of trace elements in steel were examined. Steel C, AV, HZ, J, B as base steel
Hot-dip aluminum-coated steel sheets for fuel tanks were manufactured using steels containing Q, CA, and IP, and trace elements added thereto.
Tables 16 to 18 show the amounts of the added trace elements and the experimental results. No. 334-348, 357-361, 370-3
74,383-387,396-400,409-41
3,422 to 426 are Hf, Ta, W, Tc, Re, R
u, Os, Co, Rh, Ir, Pd, Pt, Ag, A
u, Zn, Cd, Hg, Ge, Sn, Pb, As, S
Since the sum of b, Bi, Se, Te, and Po exceeded the limit, the plating adhesion was reduced. Therefore, the corrosion resistance also decreased. No. 343, 355, 369, 382, 395
For 408 and 421, since the sum of Mg, Ca, Y and REM was more than the limit, the formability was lowered. Since other experiments were within the scope of the present invention, hot-dip aluminized steel sheets for fuel tanks having good secondary workability and press workability could be produced.

[0060]

[Table 16]

[0061]

[Table 17]

[0062]

[Table 18]

Nos. 427 to 458 are steels C, J, HZ, I
The effect of manufacturing conditions was examined using P. Table 19 shows the results. At this time, the amount of Si added in the plating bath was 9.4%. Also, Hf, Ta, W, Tc, R
e, Ru, Os, Co, Rh, Ir, Pd, Pt, A
g, Au, Zn, Cd, Hg, Ge, Sn, Pb, A
The sum of s, Sb, Bi, Se, Te, and Po is 0.1% by mass.
005 to 0.019%, and the sum of Mg, Ca, Y and REM was 0.0001 to 0.0099% by mass%. In this case, the pickling cost was also examined, but the case where the cost increased by 50% or more based on the case where the winding temperature was 650 ° C. was evaluated as x. No. 428, 429, 436, 437, 444, 4
Nos. 45, 452 and 453 tended to have slightly poor formability because the hot rolling finish rolling temperature was out of the limit. No43
0, 438, 446, and 454 have a winding temperature.
Since it was out of the range of 3, the pickling cost increased. No4
32, 440, 448 and 456 have a cold rolling reduction ratio.
Since the ratio was out of the range of 3, the moldability tended to be slightly inferior. In Nos. 434, 442, 450 and 458, the moldability tended to be slightly inferior because the annealing temperature was outside the range of claim 13. In other experiments, the manufacturing conditions were within the scope of claim 13, and the plating adhesion and corrosion resistance were good, and an aluminum-plated steel sheet for a fuel tank with good secondary workability and press workability could be manufactured.

[0064]

[Table 19]

[0065]

According to the present invention, there is provided a hot-dip aluminized steel sheet having both corrosion resistance and press workability required for a fuel tank material of an automobile, and excellent secondary workability essential for an automobile fuel tank which is an important safety component. It will be Pb in the future
It is very promising as a new fuel tank material when the system material becomes difficult due to environmental problems, and has a great industrial contribution.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masahiro Futa 1-1, Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Yawata Works F-term (reference) 4K027 AA02 AA23 AB02 AB05 AB48 AC12 AC52 AE03 AE12

Claims (13)

[Claims] C .: 0.01% by mass or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two of Ti and Nb are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, B: 0.0001 to 0.00
5%, a total of 0.1% or more and 0.5% or less of one or more of Cu, Cr and Ni, with the balance being Si : 2
Rust prevention for fuel tanks excellent in secondary workability and press workability, characterized in that it has a coating layer composed of an Al-based chemical component having an Al content of at least 50% and a balance of 50% or more. steel sheet. 2. In mass%, C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.040%
Hereinafter, acid-soluble Al: 0.1% or less, N: 0.01% or less, the total of one or two of Ti and Nb in the atomic equivalent or more of (C + N) amount and 0.5% or less, B: 0 .0001-0.
005%, one or more of Cu, Cr and Ni in total of 0.1% or more and 0.5% or less, and Hf, Ta,
W, Tc, Re, Ru, Os, Co, Rh, Ir, P
d, Pt, Ag, Au, Zn, Cd, Hg, Ge, S
One or more of n, Pb, As, Sb, Bi, Se, Te, and Po contain 0.02% or less by mass%, with the balance being Fe and unavoidable impurities. Secondary workability and press workability, characterized by having a coating layer composed of an Al-based chemical component containing 2 to 13% of Si by mass% and the remaining 50% or more of Al. Excellent rust-proof steel plate for fuel tanks. 3. The method according to claim 1, wherein C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two of Ti and Nb are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, B: 0.0001 to 0.00
5%, containing one or more of Cu, Cr, and Ni in a total of 0.1% or more and 0.5% or less, and containing Mg, Ca, Y,
The sum of one or more REM is 0.01% by mass.
% On the surface of a steel sheet consisting of Fe and inevitable impurities, the balance containing Si: 2 to 13% by mass.
A rust-preventive steel sheet for a fuel tank having excellent secondary workability and press workability, characterized in that the remainder has a coating layer made of an Al-based chemical component having an Al content of 50% or more. 4. In mass%, C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two of Ti and Nb are used in a total of (C + N) equivalents of not less than the atomic equivalent and not more than 0.5%, B: 0.0001 to 0.00
5%, containing one or more of Cu, Cr, and Ni in total of 0.1% or more and 0.5% or less;
Tc, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
one or more of b, As, Sb, Bi, Se, Te, and Po is 0.02% or less by mass%, Mg, C
The sum of one or more of a, Y, and REM contains 0.01% or less by mass%, and the balance is Si: 2 to 13% by mass on the surface of a steel sheet composed of Fe and unavoidable impurities. A rust-preventive steel sheet for fuel tanks having excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component having an Al content of 50% or more. 5. C: 0.01% or less by mass%, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two or more of Ti and Nb and one or two or more of V, Mo, and Zr have a total of (C + N) equivalents of at least 0.1 atomic equivalent.
5% or less, B: 0.0001 to 0.005%, Cu, C
One or two or more of r and Ni are contained in a total of 0.002% or more and 0.5% or less, and the balance is Si: 2 to 13% by mass% on the surface of a steel sheet composed of Fe and unavoidable impurities. A rust-preventive steel sheet for fuel tanks having excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component having an Al content of 50% or more. 6. Mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
% Or less, acid-soluble Al: 0.1% or less, N: 0.01% or less, one or two of Ti and Nb and one of V, Mo and Zr
At least 0.5% or less of the atomic equivalent of (C + N) in total of two or more species, B: 0.0001 to 0.005%, C
at least one of u, Cr and Ni
Hf, Ta, W, T
c, Re, Ru, Os, Co, Rh, Ir, Pd, P
t, Ag, Au, Zn, Cd, Hg, Ge, Sn, P
The sum of at least one of b, As, Sb, Bi, Se, Te, and Po contains 0.02% or less by mass%, and the balance is expressed on the surface of the steel sheet composed of Fe and unavoidable impurities. % Of Si: 2 to 13%, with the balance having a coating layer composed of an Al-based chemical component having an Al content of 50% or more, which is excellent in secondary workability and press workability. Rustproof steel plate for fuel tank. 7. In mass%, C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two or more of Ti and Nb and one or two or more of V, Mo, and Zr have a total of (C + N) equivalents of at least 0.1 atomic equivalent.
5% or less, B: 0.0001 to 0.005%, Cu, C
One or more of r and Ni are contained in a total of 0.002% or more and 0.5% or less, and 1% of Mg, Ca, Y, and REM are contained.
Species or the sum of two or more contains 0.01% or less by mass%, the balance contains Si: 2 to 13% by mass on the surface of a steel sheet composed of Fe and unavoidable impurities, and the balance contains Al
A rust-preventive steel sheet for a fuel tank having an excellent secondary workability and press workability, comprising a coating layer comprising an Al-based chemical component having a content of 50% or more. 8. In mass%, C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One or two or more of Ti and Nb and one or two or more of V, Mo, and Zr have a total of (C + N) equivalents of at least 0.1 atomic equivalent.
5% or less, B: 0.0001 to 0.005%, Cu, C
Hf, Ta, W, Tc, R containing one or more of r and Ni in a total content of 0.002% or more and 0.5% or less.
e, Ru, Os, Co, Rh, Ir, Pd, Pt, A
g, Au, Zn, Cd, Hg, Ge, Sn, Pb, A
The sum of one or more of s, Sb, Bi, Se, Te, and Po is 0.02% or less by mass%, Mg, Ca, Y,
The sum of one or more REM is 0.01% by mass.
% On the surface of a steel sheet consisting of Fe and inevitable impurities, the balance containing Si: 2 to 13% by mass.
A rust-preventive steel sheet for a fuel tank having excellent secondary workability and press workability, characterized in that the remainder has a coating layer made of an Al-based chemical component having an Al content of 50% or more. 9. In mass%, C: 0.01% or less, Si:
0.2% or less, Mn: less than 0.6%, P: 0.04% or less, acid-soluble Al: 0.1% or less, N: 0.01% or less,
One, two or more of V, Mo, and Zr are (C +
N) Atomic equivalent or more of the amount and 0.5% or less, B: 0.0001
0.005%, one or two or more of Cu, Cr and Ni are contained in a total amount of 0.002% or more and 0.5% or less, and the balance is expressed on the surface of a steel sheet composed of Fe and inevitable impurities. % Of Si: 2 to 13%, with the balance having a coating layer composed of an Al-based chemical component having an Al content of 50% or more, which is excellent in secondary workability and press workability. Rustproof steel plate for fuel tank. 10. In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, one or more of V, Mo and Zr in total (C
+ N) not less than the atomic equivalent of the amount and not more than 0.5%, B: 0.000
1 to 0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% to 0.5%,
Hf, Ta, W, Tc, Re, Ru, Os, Co, R
h, Ir, Pd, Pt, Ag, Au, Zn, Cd, H
g, Ge, Sn, Pb, As, Sb, Bi, Se, T
e, the sum of one or more of Po is 0.0% by mass.
Al based chemical component containing 2% to 13% by mass of Si on the surface of a steel sheet containing 2% or less, the balance being Fe and unavoidable impurities, and the balance being 50% or more. A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of: 11. In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, and one or more of V, Mo and Zr in total (C
+ N) not less than the atomic equivalent of the amount and not more than 0.5%, B: 0.000
1 to 0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% to 0.5%,
The sum of one or more of Mg, Ca, Y, and REM contains 0.01% or less by mass%, and the balance is on the surface of a steel sheet composed of Fe and unavoidable impurities.
A containing 13%, with the balance being 50% or more of Al
A rust-preventive steel sheet for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer composed of an l-type chemical component. 12. In mass%, C: 0.01% or less, S
i: 0.2% or less, Mn: less than 0.6%, P: 0.04
%, Acid-soluble Al: 0.1% or less, N: 0.01% or less, one or more of V, Mo and Zr in total (C
+ N) not less than the atomic equivalent of the amount and not more than 0.5%, B: 0.000
1 to 0.005%, containing one or more of Cu, Cr and Ni in a total amount of 0.002% to 0.5%,
Hf, Ta, W, Tc, Re, Ru, Os, Co, R
h, Ir, Pd, Pt, Ag, Au, Zn, Cd, H
g, Ge, Sn, Pb, As, Sb, Bi, Se, T
e, the sum of one or more of Po is 0.0% by mass.
2% or less, the sum of one or more of Mg, Ca, Y, and REM contains 0.01% or less by mass%, and the balance is F
e and unavoidable impurities, the surface of the steel sheet contains 2 to 13% of Si by mass%, and the balance has an Al content of 50%.
A rust-preventive steel plate for a fuel tank having an excellent secondary workability and press workability, characterized by having a coating layer comprising an Al-based chemical component of at least 0.1%. 13. A hot-rolled steel ingot of the steel composition according to claim 1 which is heated at a temperature of at least 1000 ° C., then hot-rolled at a temperature of at least Ar ₃ , cooled and wound up at a temperature of 800 ° C. or less. After the steel sheet is pickled and cold rolled at a rolling reduction of 50% or more, the steel sheet is heated to a temperature higher than the recrystallization temperature in a hot-dip plating line and cooled after the steel sheet is recrystallized.
The second workability and the press workability are characterized in that after plating is made of an Al-based chemical component having an Al content of 50% or more, the balance is controlled by gas wiping. An excellent method for producing rust-proof steel plates for fuel tanks.