JPS6347356A - Production of aluminum plated steel sheet for fuel exhaust having excellent corrosion resistant performance - Google Patents

Abstract

PURPOSE:To obtain a titled steel sheet which exhibits excellent corrosion resistance as a stock for an exhaust pipe of an automobile, etc., by subjecting one face of the steel sheet contg. C, Cr, solAl as essential components to underling plating of Ni and Ni-Fe alloy, then to an aluminum plating treatment. CONSTITUTION:The plating treatment is executed on one face of the steel sheet contg., by weight %, <=0.02% C, 3-20% Cr, 0.005-0.10% solAl, and 0.03-0.5% >=1 kinds among Ti, Nb, Zr, and V in the following manner. The Ni or Ni-Fe alloy layer of 0.5-5g/m<2> in terms of Ni is provided on one face of the steel sheet in order to form the alloy layer having less defects thereon to >=6mu thickness. The steel sheet provided with said alloy layer is then subjected to hot dip coating in an Al-Si alloy plating bath (620-690 deg.C plating bath temp.) contg. 5-13% Si. The aluminum plated steel sheet which has the above-mentioned characteristics and exhibits the excellent corrosion resistance to sprayed salt for preventing freezing of roads, etc., is thus obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention has excellent corrosion resistance as a material for exhaust pipes and mufflers used as leaded gasoline fuel containing a large amount of halogen ions and heavy metals in automobiles, motorcycles, etc. The present invention also relates to a method for producing an aluminized steel sheet that has excellent corrosion resistance against salt sprayed to prevent roads from freezing.

(Prior art and problems to be solved by the invention) The materials used for exhaust systems after fuel combustion (e.g., mufflers, till pipes, center tubes, etc.) of automobiles, two-wheeled motorcycles, etc. have traditionally been aluminized steel sheets. , Cr-containing stainless steel plates, etc. have been used.

However, in recent years, due to improvements in engine efficiency and the use of catalytic converters in line with exhaust gas regulations, changes in exhaust gas temperature, qualitative changes in exhaust gas condensate, and the effects of spraying salt to prevent roads from freezing in the winter, etc. However, with the above-mentioned materials, problems have arisen in which it is difficult to ensure a sufficient corrosion-resistant life.

Although aluminized steel sheets have excellent corrosion resistance against salt sprayed to prevent road icing, when used as a material for exhaust systems, the corrosion resistance life is extremely poor against corrosive factors in exhaust gas condensate, especially leaded steel sheets. When used for gasoline fuel, corrosion from the inside is extremely severe.

On the other hand, although Cr-containing stainless steel sheets have fairly good corrosion resistance against exhaust gas condensate, they are extremely susceptible to red rust when exposed to external corrosive factors such as sprayed salt, and there is also concern about perforation corrosion. It is not always fully satisfactory in terms of commercial value and corrosion resistance life.

In addition, as a solution to these problems, a steel plate with an aluminized layer applied to a Cr-containing steel plate is available, for example in Japanese Patent Application Laid-Open No.
No. 101455 and Japanese Unexamined Patent Publication No. 60-262950.

In other words, in order to obtain aluminized steel sheets with excellent corrosion resistance and isovolume performance, these steel sheets contain 3 to 18% Cr as an essential component.
A method of aluminizing by applying 02 to 2 g/m2ONi plating (Japanese Patent Application No. 101455/1982), a method of aluminum plating by regulating the St content of the plating original plate that promotes the formation of plating defects (Japanese Patent Application No. 1983-101455) 59-116564), etc.

Although each of these steel sheets has achieved excellent performance as a material for fuel exhaust systems for automobiles, particularly as a material for mufflers, they may not always be satisfactory depending on the environment in which they are used.

That is, the aluminized steel sheet contains Ct″″ ions, Pb
When used with leaded gasoline that contains a large amount of 2+ ions, etc., the aluminum plating layer dissolves due to a substitution reaction with lead chloride, resulting in insufficient corrosion resistance against exhaust gas condensate and in preventing roads from freezing in winter. When a large amount of spray salt is sprayed, the corrosion resistance against corrosion on the external surfaces of exhaust pipes, mufflers, etc. has not always been satisfactory.

The present invention addresses these situations, and in particular improves the corrosion resistance of aluminized steel sheets against exhaust gas condensate, and also ensures excellent corrosion resistance against the corrosion of sprayed salt for road anti-icing purposes. The purpose was to provide a method for manufacturing aluminized steel sheets.

(Means for Solving Problems) The gist of the present invention is as follows: (1) In weight f%, C: 0.02% or less Cr; 3 to 20% Acidizable g Az; 0.005 to 0 .10% Tl,
Nb, Zt, V (7) 0.0 for one or more types
Ni content of 0.5 g/m2 to one side of a steel plate containing 3 to 0.5% and the remainder consisting of iron and unavoidable impurities.
Excellent corrosion resistance, characterized by applying a Ni, Ni-Fe alloy base plating layer of 5gI/m, and then performing aluminum plating using an Al-Si plating bath with a Si content of 5 to 13T. A manufacturing method for aluminized steel sheets for fuel exhaust.

(2) C: 0.02 or less Cr; 3 to 20% Acid-soluble Al: o, oos to 0.10%; one or two of Ti, Nb, Zr, and V; 0. 03～
Ni content of 0.5 ji/m2 is applied to one side of a steel plate containing 0.50% Ni with the remainder being iron and unavoidable impurities.
After applying a Ni or Ni-Fe alloy base plating layer of ~5 g/m2 and applying a Ni or Ni-Fe alloy base plating layer with an Ni amount of 0.5 g/m or less on the other side, S
A method for producing an aluminized steel plate for fuel exhaust with excellent corrosion resistance, characterized by carrying out aluminizing treatment using an Al-Si based plating bath with an i content of 5 to 13%.

(3) C in weight%: 0.02 or less Cr: 3 to 20 Thiric acid soluble Al: 0.005 to 0.10 Tl, Nb, Zr, VO 2 types or 2 or more types 0.03 to
Contains 0.50S, Ni: 3% or less, Mo:
1% or less, Cu: 1% or less, and the balance is iron and unavoidable impurities.
, Aluminum plating for fuel exhaust with excellent corrosion resistance, characterized in that after applying a Ni-Fe alloy base plating layer, aluminum plating is performed using an m-5i plating bath with a Si content of 5 to 13 es. Manufacturing method of steel plate.

(4) C: 0.02% or less Cr: 3-20 Thiric acid soluble Al: 0.005-0.10% One or more of Ti, Nb, Zr, and V with 0.0%. 03～
Contains 0.50'%, Ni: 3% or less, Mo:
1% or less, Cu: 1% or less, and the balance is iron and unavoidable impurities.
, a Ni-Fe alloy base plating layer is applied, and the other side is coated with 0.5117 m2 or less of Ni.

Aluminum plating for fuel exhaust with excellent corrosion resistance, characterized by applying a Ni-Fe alloy base plating layer and then performing aluminization using an Al-8L plating bath with a Si content of 5 to 13%. This is a method of manufacturing steel plates.

Aluminum-plated steel sheets, which are aluminum-plated steel sheets containing 3% or more of Cr, especially 5% or more of Cr, are free from ammonium, ammonium nitrate, ammonium sulfate, and formaldehyde contained in fuel exhaust gas or their condensates. It shows excellent corrosion resistance against aldehydes such as saccharic acid and organic acids such as formic acid.

However, when the exhaust gas or the condensate of the exhaust gas contains many substances such as lead chloride, halogen ions such as Ct- ions, and metal ions that have a higher potential than aluminum, these The aluminized layer is severely corroded by the condensed aqueous solution.

That is, the corrosion-resistant passive film formed on the surface of the aluminum plating layer is destroyed by Ct'' ions and other ions, and a metal more harmful than aluminum is precipitated by a substitution reaction. As a result, corrosion of the aluminized layer is accelerated.

Furthermore, although Cr-containing plated plates exhibit excellent corrosion resistance against sulfuric acid, nitrate ions, organic acids, etc., leaded gasoline, which contains a large amount of C4- ions, causes perforation corrosion and shortens the corrosion resistance life. descend. Therefore, in order to solve these problems, as a result of various studies, we found that Al, Si, and Fa were added to the intermediate layer between the Cr-containing plating original plate and the aluminum plating layer.
It has been found that corrosion resistance can be obtained by forming a Cr-containing alloy layer whose main component is K, even if a large amount of Ct"" ions such as lead chloride and heavy metals are contained.

Figures 1 and 2 show the corrosion resistance of 5L% Cr-containing steel aluminized steel plates with different alloy layer thicknesses in a lead chloride-containing aqueous solution targeting leaded gasoline.

The conditions shown in FIG. 1 are shown below.

1 Al-Si excluding the alloy layer thickness from the total plating thickness
The plating thickness was adjusted to 12μ thick (chromate treatment of 15 In97m on the surface of the aluminized steel plate) 2 Evaluation test method 0, 1 PbC42-0.1% (Ni(4) 2so4
Using a system aqueous solution, immersion at 60℃ for 10 minutes, and immersion at 80℃ for 3 minutes.
Evaluated by the number of pitting cycles of the evaluation material of 0.8 minutes, with drying and heating for 1 minute ◎...Number of pitting corrosion occurrence cycles 2000 cycles or more○・
・・z 1500 cycles or more ~ 2000
Less than cycle Δ...〃 1000 cycles or more ~ 150
Less than 0 cycles X...p Less than 1000 cycles The conditions shown in FIG. 2 are shown below.

1 Al-Si excluding the alloy layer thickness from the total plating thickness
The plating thickness was adjusted to 8μ thick (chromate treatment of 15μ/m2 on the surface of the aluminized steel plate) 2. Corrosion reduction was 3011/L Cr05 at 90℃ after the test.
-20 E/l Calculated based on the amount of corrosion products removed by immersion in an aqueous H3PO4 solution for 10 minutes.

As is clear from this result, the thicker the alloy layer is, the better the corrosion resistance is, and particularly when the thickness exceeds 6μ, the corrosion resistance is good.

On the other hand, the external corrosion resistance of the exhaust pipe or muffler, especially the corrosion resistance to sprayed salt for road anti-freezing, is extremely effective in preventing corrosion of the alloy layer of the aluminum plating layer and the plated original plate. Although the corrosion-resistant passive technology film, which is mainly composed of an oxide film formed on the surface of the aluminum plating layer, is destroyed by Ct- ions, the aluminum plating layer has an excellent repair effect, and the alloy layer and plating It is thought to protect the original plate from corrosion.

However, when the alloy layer is thick and the aluminum plating layer is thin, the dissolution rate of the aluminum plating layer increases due to the sacrificial anticorrosion effect on the defective parts of the aluminum plating layer with respect to the alloy layer and the plating original plate, and the corrosion resistance performance deteriorates.

Therefore, it is preferable that the alloy layer be provided with a relatively thin thickness of 6 μm or less.

As described above, the corrosion behavior of aluminized steel plates for fuel exhaust differs significantly between the inner and outer surfaces of the exhaust system, and in order to obtain good corrosion resistance, the coating composition also differs as described above. For this reason, as a result of various studies on how to obtain aluminum plated products that titrate both of these corrosion resistance performances, we found that:
The aluminum plating layer has a sacrificial anti-corrosion effect, preventing plating defects,
A plating base plate containing 3% or more of Cr as an essential component is used to prevent preferential corrosion of the plated base plate/Fe from the end face portion during product use.

(b) On one side of the steel plate intended for the inner surface of the exhaust system,
In order to generate an alloy layer with less defects and a thickness exceeding 6 μm, the amount of Ni is 0.5 g/m to 51//m.
In order to provide an alloy layer of i, Ni-Fe, and an aluminum plating layer consisting of an alloy layer with a thickness of 6μ or less on one side of the hook plate intended for the outer surface of the exhaust system, the amount of Ni was 0.
．． 5g/m or less Ni, Ni-Fe, Ni-
It has been found that the steel sheet targeted by the present invention can be obtained by providing a co alloy layer and performing aluminization treatment in an Al-Si alloy plating bath.

The details of the present invention will be explained below.

In the present invention, the plated original plate contains Cr as an essential component.
A steel plate containing 3% to 20% of is used.

As mentioned above, Cr has an aluminum plating layer that has a sacrificial anticorrosion effect against exhaust gas condensate, and prevents plating defects and
This is effective in preventing deterioration of the corrosion resistance life due to perforation corrosion due to preferential dissolution of Fe from the exposed parts of the plated original plate, such as the flawed parts of the plated layer due to processing or the end faces during use.

However, if the Cr content is less than 3 tres, the potential of the plated original plate with respect to the condensate becomes more base than the aluminum plating layer, and this is not preferable because drilling corrosion occurs from the plated original plate.
Furthermore, if the Cr content exceeds 20%, these effects will be saturated, and workability and weldability will deteriorate, making processing and installation into exhaust pipes and mufflers unfavorable from the viewpoint of work. Therefore, Cr contents in the range of 3 to 20 inches, preferably 5 to 15 inches, are used in the present invention.

As mentioned above, Cr has the greatest effect in terms of corrosion resistance, but in the present invention, from the viewpoint of targeting materials for solvent exhaust pipe systems of automobiles and other vehicles, C and acid-soluble AlO steel components are also considered. Limit content.

As the C content increases, chromium carbide is precipitated and the mechanical properties and corrosion resistance of steel deteriorate.

Therefore, the C content is 0.02% or less, preferably 0.0
1% or less is desirable.

Al is acid-soluble Al (sol, Al
) If the amount of ungrooved steel is o or ooss, it is difficult to prevent the generation of bubbles due to oxygen gas, which significantly increases the incidence of surface defects in steel and becomes the starting point for deterioration of the corrosion resistance of the steel material. In addition, excess acid-soluble Al exceeding 0.10% is
The system oxides are scattered on the steel surface, which is the starting point for deterioration of corrosion resistance, or causes non-plating, pinholes, etc. on the surface of the plating layer applied to the steel sheet, impairing the integrity of the surface of the plating layer.

Therefore, acid-soluble Al-11 in steel ranges from 0.005% to 0.
．． 10%, preferably 0.01 to 0.08 h.

In addition, the present invention includes 0.03 to 0.50 of one or more of Tl, Nb, Zr, and V in the above steel components to combine with C in the steel to increase the effectiveness of Cr contained in the steel. This will further improve moldability and corrosion resistance.

If the content of steel components such as Tl and Nb is less than 0.03%, the effect of preventing chromium carbide precipitation and improving formability and corrosion resistance will be small, and the content will remain below 0.50%. The effect reaches saturation and becomes uneconomical, and the precipitation of these components tends to harden the material and deteriorate moldability. Particularly preferably, the content of these elements is 0.075 to 0.20%
is within the range of

Furthermore, the plated original plate used in the present invention has the above-mentioned C
r1l, C amount and acid-soluble Al! In addition to k, plating properties,
From the viewpoint of corrosion resistance, workability, etc., it is preferable to restrict the following elements, and in order to improve other performances such as pickling properties and material reinforcement, required elements may be added as described below.

For example, the following ranges are preferable for Mu and Si.

Mn is 0.1-1.5%, preferably 0.2-1.0
It is Chi.

MnFi, which increases the pickling properties of the steel surface and increases the uniformity of the Ni-based underplating treatment in the pretreatment of the Ni-based underplating, that is, the pickling activation treatment performed in the present invention. The higher the amount, the better, 0.1%
The content is preferably 0.2% or more. However, a large amount of Mn hardens the steel, deteriorates formability, and tends to cause the aluminum plating layer to peel off during processing.
．． It is preferably 5 inches or less, preferably 1.0 inches or less.

Further, the Si content is 0.4 inch or less, preferably 0.1 inch or less.

If the Si content exceeds 0.4'%, Si and Si oxides will be concentrated and enriched on the surface of the plated original plate during the heating process (annealing and reduction process) of pre-plating treatment, which will inhibit plating properties. Easy to generate plating defects such as pinholes,
Corrosion resistance and plating adhesion are impaired.

In addition, an increase in Ni content hardens the steel, so
It is also not preferable from the viewpoint of moldability.

Therefore, the Si content in the steel is 0.4% or less, preferably 0.1% or less.

Furthermore, in order to further improve corrosion resistance, the present invention uses Ni and Cu in the following ranges.

One or more types of Mo are added to the plated original plate.

Since Nf, Cu, and Mo improve the corrosion resistance of the plated original plate itself, they are advantageous in terms of corrosion resistance life when used as exhaust system materials.

Therefore, Ni is 0.1 to 3%, preferably 0.15 to 1%.
迤, Mo is 0.05 to 1%, preferably o, 1 to 0.5
迤, Cu is 0.1 to 1%, preferably 0.15 to 0.5
% of one type or two or more types are added. Each lower limit is a content that improves the corrosion resistance of steel.

However, if the Ni content exceeds 3, the corrosion resistance improvement effect will be saturated and the surface will not be sufficiently reduced during the reduction/annealing process, resulting in the formation of plating defects such as pits and pinholes. It becomes easier. Therefore, the Ni content is preferably 3% or less, particularly 1% or less.

When Mo and Cu exceed 1%, the material hardens, deteriorating molding processability, and making it easier for the coating layer to peel off during processing.

Therefore, each of Cu and Mo is added in an amount of 1 tre or less, preferably 0.5 tres or less.

Therefore, when a steel plate having the above-mentioned composition is used as it is as a material for a fuel exhaust system, the corrosion resistance performance is insufficient.

Therefore, in the present invention, in order to obtain an aluminized steel sheet having the above-described coating structure, an aluminizing treatment is performed as follows.

That is, on one side of the steel plate that is exposed to exhaust gas or exhaust gas condensate, an alloy layer with a thickness exceeding 6 μm is formed as an intermediate layer between the steel plate surface and the aluminum plating layer.
In addition, in order to ensure external corrosion resistance, the thickness of the alloy layer on one side of the steel plate must be 6 μm or less, as shown in FIG.

As a result of various studies on the method of producing aluminized steel sheets with such a coating structure, we found that (,) the surface of the steel sheet where the alloy layer is thicker than 6 μm and makes it look unsightly has a Ni content of 0.5 fl/m2. ~5g/m2 of Ni, N
i-Fe alloy base plating layer.

(b) For steel plates on which an alloy layer is formed with a thickness of 6μ or less, Ni of 0.5g/m2 or less as Ni,
Ni-Fe alloy base plating layer.

Al-Si with a Si content of 5% to 13T
By carrying out hot-dip plating in a plating bath containing an alloy based on the alloy (with a plating bath temperature of 620 to 690° C.), an aluminized steel sheet having the coating structure and corrosion resistance that is the object of the present invention can be obtained. Compared to a hot-dip aluminum plating bath, the Ni and Ni--Fe alloy plating layer of the present invention has a remarkable effect of improving the wettability and reactivity of the plating bath, even on the steel surface.

Therefore, in the present invention, Ni is added to the surface of the Cr-containing steel sheet.
By applying a system base plating layer, the wettability of the aluminum plating bath is improved, plating defects such as pinholes are extremely reduced, and a metal layer with excellent uniform coverage is produced. Under the same plating conditions, the alloy layer tends to be thick and easily formed.

This tendency is observed when Ni, Ni-Fe plated plates are plated.
As the amount of Ni in the alloy plating layer increases, it becomes significantly larger. Therefore, in order to obtain an aluminized steel sheet having a coating structure in which the front and back sides of the steel sheet have different alloy layer thicknesses, which is the object of the present invention, Ni with different Ni il on the front and back sides, respectively, is applied prior to hot-dip aluminizing. By providing a Ni--Fe alloy plating layer and performing hot-dip aluminum plating, aluminized steel plates with different alloy layer thicknesses on the front and back surfaces can be easily produced under the same hot-dip aluminizing conditions.

Therefore, in the present invention, in order to achieve the desired coating structure and effect, Ni is applied to both the front and back surfaces.
, The thickness of the Ni-Fe alloy base plating layer is important.

As a result of various studies, it was found that the amount of Ni should be 0.51 for one side, which is the inner surface exposed to exhaust gas and exhaust gas condensate.
By providing a Ni, Ni-Fe alloy layer of ~5117m2 and applying hot-dip aluminum plating in an Al-8S plating bath under the above conditions, aluminum with an alloy layer thickness of more than 5μ has improved corrosion resistance on the inner surface. A plated steel plate is obtained.

In other words, the thickness of the base plating layer is 0.5 g as the amount of Ni.
/m2 or less, the effect of uniformly forming an alloy layer by improving the wettability of the aluminum plating bath and the effect of preventing pinholes can be obtained.
It is difficult to create an alloy layer thicker than μ.

On the other hand, Ni exceeds 5 jj/m as Nift.

In the case of base plating made of Ni-Fe alloy, the pinhole prevention effect and the effect of forming a thick alloy layer are saturated, and when the base metal becomes thicker, the alloy layer that is generated and the influence of the base metal cause problems during forming. Cracks are more likely to occur.

Therefore, 0.5 g/m of Ni is added to the base plating layer.
2-5I/m2 preferably 0.717m2-3.5y/
, 2, a base plating layer of Ni, Ni-Fe alloy is provided.

On the other hand, on one side, which is intended for corrosion resistance against sprayed salt for preventing road icing, N
i. A base plating layer of Ni-Fe alloy is provided.

When the amount of Ni is 0.5 g/m2 or more, as described above, the thickness of the produced alloy layer exceeds 5 μm, which reduces the free aluminum plating layer and deteriorates the corrosion resistance of the outer surface against sprinkled salt.

Furthermore, if Ni-based surface treatment is not performed, it is difficult to prevent the formation of plating defects such as pinholes, but a good corrosion-resistant life can be obtained due to the combined effect of the plating original plate and the aluminized plating layer.

Therefore, in order to ensure the corrosion resistance of the outer surface, the alloy layer thickness is 6 μm.
Below, preferably 4μ or less, Ni amount is 0.5g/m
Below, preferably 0.05 to 0.4 Ji'/m 2
A base plating layer of Ni and Ni-Fe alloy is provided.

It should be noted that the method of providing these Ni and Ni--Fe base coating layers is not particularly specified.

For example, surface cleaning such as degreasing and pickling of the plated original plate surface,
After performing the activation treatment, it is provided by an electroplating method, an aqueous solution coating method, or the like.

Further, Co, S, etc. may be contained as impurities from the chemicals, electrodes, etc. used in the above-mentioned surface treatment. In particular, although Co metal is contained in a relatively large amount in the Ni source, N
Approximately 25 units may be included since almost the same effect as i can be obtained.

Regarding the composition of the Ni-Fe alloy base plating layer,
From the viewpoint of improving the wettability of the aluminum plating bath for these base plating layers and uniformly forming an alloy layer, Ni containing 10% or more of Ni is used.
-Fe alloy plating layer is desirable.

Next, the material to be plated, on which the base Ni-based plating layers were provided with different thicknesses on the front and back sides, had a Si content of 5 to 50%.
In a 13-chi Al-Si plating bath, the temperature is 620-69
Hot-dip plating is applied at 0° C. for a dipping time of 1 to 10 seconds, followed by controlling the amount of plating and cooling to produce an aluminized steel sheet. As is conventionally known, the Si content in an aluminum plating bath is important for ensuring the effect of suppressing the growth of the alloy layer. It is difficult to

Furthermore, if the Si content is 13 or more, the alloy layer is not formed uniformly, but is formed in an uneven manner, which is not preferable in terms of corrosion resistance and plating adhesion. Therefore, an Al-Si bath with a Si content of 5 to 13, preferably 6 to 12, is used, and Fe, Cr, and Even if Ni or the like is dissolved or mixed into the plating bath as an impurity, it is not a big problem.

In addition, the plating temperature and dipping time during plating were 620°C, respectively.
Hot-dip plating is carried out at a temperature of ~690°C for a dipping time of 1 to 10 seconds, but due to the mutual effect with the amount of the Ni-based undercoating layer provided before the aluminum plating process, each of the present invention Plating conditions within this range are adopted in order to generate the desired alloy layers with different thicknesses on the front and in the middle of winter.

That is, if the plating temperature is less than 620° C. or the dipping time is less than 1 second, it is difficult to obtain a thick alloy layer of more than 6 μm even if the Ni-based base plating is applied as described above.

Furthermore, if the plating temperature exceeds 690°C or the immersion time exceeds 10 seconds, it is difficult to obtain a thin alloy layer of 6μ or less even if the amount of Ni-based undercoating is controlled as described above. becomes difficult.

Therefore, the plating temperature is 620-690°C, preferably 620-690°C.
40-680℃, immersion time is 1-10 seconds, preferably 2
．． It is desirable to perform the plating treatment within a range of 5 to 7.5 seconds.

In addition, the product is made by air cooling or water cooling after plating, but in this process, especially on one side where a thin alloy layer is formed, there is a method that strengthens the cooling effect to reduce the amount of alloy layer formed. may be adopted.

As described above, the aluminized steel sheet manufactured by the method of the present invention not only ensures a corrosion-resistant life on one side exposed to exhaust gas or its condensate due to the excellent corrosion resistance of the alloy layer, but also By ensuring the corrosion-resistant life of one side exposed to sprayed salt and the like with a free aluminum plating layer, a steel plate with extremely excellent corrosion resistance can be obtained.

Incidentally, in order to further improve the corrosion resistance of these exhaust system materials, particularly to improve the corrosion resistance against corrosion from sprayed salt, etc., a chromate treatment may be applied to the surface of the steel plate produced by the method of the present invention.

For this chromate-based treatment, an aqueous solution containing Cr'+ as an essential component, or an aqueous solution to which ions are added, for example, a CrO3 aqueous solution containing silicate, F.
- 1 or 2 ions, SO4 ions, PO4 ions, etc.
immersion treatment, electrolytic treatment, or immersion treatment using an aqueous solution to which a water-soluble resin or more has been added, or a water-soluble resin to these aqueous solutions.
A chromate coating treatment is performed by a method such as a tt spray treatment.

Therefore, excellent effects can be obtained by applying a chromate coating with a chromate coating amount of 10 to 150 µ/rrs (per one side), preferably 15 to 100 µ/rr. ,preferable.

(Example) Examples of the present invention will be described below.

Example-I Using cold-rolled materials (As Cotti materials) having the steel composition shown in Table 1, a predetermined amount of Ni base plating was applied to each material by electroplating after degreasing and pickling, surface cleaning, and activation treatment. After heating at 840°C for 30 seconds in a reducing atmosphere,
Using an aluminum paste St-containing alloy plating bath, hot-dip aluminized steel plates having different thicknesses of front and mid-winter alloy layers were obtained.

In addition, for the aluminized steel plate, 20 ji/lC
A chromate treatment was performed using an rO3-60yA colloidal silica bath with a Cr coating amount of I) 15 F4/ln per side. The performance evaluation results of this aluminized steel sheet are shown in Table 2, and the present invention showed superior corrosion resistance performance compared to the comparative material.

Regarding the performance evaluation, the evaluation was carried out using the evaluation material having a plate thickness of 1.2 sheets and using the performance evaluation test and evaluation criteria shown below.

When applied to a corrosion-resistant exhaust system targeting exhaust gas condensate, the corrosion-resistant performance of the evaluation material was evaluated using the following method on one side of the inner surface. That is, an evaluation test was conducted using the following accelerated test for leaded gasoline and unleaded gasoline, and each was relatively evaluated using the evaluation criteria shown below.

■Evaluation test■ Targeting exhaust gas condensate, 1. OgA(NH4)2SO4
-O,511/l NH4No5-0.59/l Pb
Using a Cl2-based aqueous solution, place the above solution and the evaluation material in a sealed container, and adjust the solution temperature to 80°C so that half of the evaluation material is immersed in the solution and the upper half is exposed to the gas phase.
A 30-day side test was conducted and evaluated using the following evaluation criteria.

◎...The maximum drilling corrosion depth of the corroded part is less than 0.2 y O
... I O 12 wins or more - less than 0.40 m Δ... I 0.40 m or more - 0.
Less than 60 meters
An evaluation test was conducted at 80° C. for 30 days under the same test conditions as above using a PbCl2-0.5 thiformic acid-0.5 tisucic acid aqueous solution. The evaluation criteria were as follows.

◎・・・Maximum drilling corrosion depth of corroded part is less than 0.15m○
-/l O, 15m or more ~ less than 0.30m Δ...
・ r 0.30++am or more ~ 0.5
Less than 0m+×・・・ I O, 50m
Above ■ Evaluation test ■ Targeting exhaust gas condensate, 1 jj/II (NH4)2
SO4-1, 5gl/l NH4N03-0.51/l
Using the NH4C2-0,05 thiformin-based aqueous solution, an evaluation test was carried out at 80 DEG C. for 30 days in the same manner as described above, and the evaluation test was evaluated based on the evaluation criteria of ◎.

The corrosion resistance performance of one side of the exhaust system, which is intended to be applied to the external surface of a corrosion-resistant exhaust system that targets corrosion caused by spray fields, etc., was evaluated using the following method.

(2) Corrosion resistance by salt spray test The corrosion loss after 30 days of the salt spray test was measured and evaluated using the following evaluation criteria.

◎・・・Corrosion loss is less than 5g/m2 per side○・-・t
p S 17m2 or more - less than 10y/rn2 Δ-
・-tt 10! Vfn or more~25,! i'
Less than /mX ・-・I 251/lm or more■
Corrosion resistance by cyclic collodion test (C, C, T) An evaluation test was carried out for 120 cycles, with the cycle conditions shown below as one cycle, and the corrosion resistance was evaluated using the following evaluation criteria.

◎・・・Corrosion loss is 10117m2 per side without groove ○-1
101/lm or more to less than 15 g/mΔ... p
15 g/m2 or more to less than 25 ladle

Example - Cold rolled material (As Co1d material) with steel composition shown in Table 3
After degreasing, surface cleaning by pickling, and activation treatment, a predetermined amount of Ni base plating was applied to each by electroplating, and after heat treatment at 780°C for 60 seconds in a reducing atmosphere, aluminum-based Al- Using a Si-based alloy plating bath,
Hot-dip aluminized steel plates with different alloy layer thicknesses were obtained in the middle of winter.

30 ji/l Cr0 for the aluminized steel plate
5-101/l colloidal silica-51/l titanium fluorosilicide-0.51 i/l 7 Using an aqueous solution containing hydrogen fluoride, chromate treatment was performed to give a coating weight of 25 to 1/m on one side.

The performance evaluation and results of this aluminized steel sheet are shown in Table 4, and the present invention showed superior corrosion resistance performance compared to the comparative material.

Regarding performance evaluation, evaluation was carried out using the evaluation material with a plate thickness of 0.8 cm according to the performance evaluation test and evaluation criteria shown below.

When applied to a 9-corrosion resistant exhaust system targeting exhaust gas condensate, the corrosion resistance performance of the evaluation material was evaluated using the following method on one side, targeting the inner surface. That is, an evaluation test was conducted using the following accelerated test for leaded gasoline and unleaded gasoline, and each was relatively evaluated using the evaluation criteria shown below.

■Evaluation test■ Targeting exhaust gas condensate, 1.0 E/l (NH4)2
So4-0.51//l NH4No5-0.59/l
Using a PbCl2-based water solution, place the above solution and the evaluation material in a sealed container, and bring the solution temperature to 80°C so that half of the evaluation material is immersed in the solution and the upper half is exposed to the gas phase. A side test was carried out at ℃ for 45 days, and the evaluation was made according to the following evaluation criteria.

◎...The maximum drilling corrosion depth of the corroded part is less than 0.2 ta○...fl 0.2 m or more
0.40m ungrooved Δ.../F O, 4
0m or more - less than 0.60■...1
0.60w or more ■ Evaluation test ■ Test similar to the above using 0.1% H2So4-0.1% PbCl2-0.5% thiformic acid-0.5% tysuccinic acid based aqueous solution for exhaust gas condensate. An evaluation test was conducted at 60° C. for 60 days. The evaluation criteria were as follows.

◎・・・Maximum drilling corrosion depth of corroded part is less than 0.15m○
... IO, 15m or more ~ 0.
Less than 30+ms+ Δ... I O
, 30van or more - less than 0.50■...
s O, 50m or more ■ Evaluation test ◎ Targeting exhaust gas condensate, 111/l (Book 4) 2804
-1,5 g/l NH4No3-0.5 VI Ni
(Using a 4Ct-0,05 thiformin-based aqueous solution, an evaluation test was carried out at 80° C. for 45 days in the same manner as described above, and the evaluation was performed according to the evaluation criteria of evaluation test ①.

Corrosion resistance against corrosion caused by sprayed salt, etc. The corrosion resistance performance of one side of the exhaust system, which is intended for application to the external surface, was evaluated by the following method.

■ Corrosion resistance by salt spray test Corroded area after 30 days of salt spray test 1. was measured and evaluated using the following evaluation criteria.

◎...Corrosion loss is less than 5 g/m2 per side○...
tt S 17m or more~10j! /m
Less than Δ...' 10 g/m2 or more to less than 25 g/n2×... 1 25 g/
m or more ■ Cyclic coro-zoo test (C, C
, T) A 120-cycle evaluation test was conducted using the cycle conditions shown below as one cycle, and the corrosion resistance was evaluated using the following evaluation criteria.

◎・・・Corrosion loss is less than 10 Vrn2 per side ○-#
10 g/m2 or more - less than 15,9/rn2 Δ...p 15 g, 4 or more - 25I
Less than 24 ×... 1 25 El/ln
FIG. 4 shows the cycle test conditions.

[Brief explanation of the drawing]

Figure 1 shows the alloy layer thickness and corrosion resistance against exhaust gas condensate of a Cr-containing T5 aluminum plated steel plate with Nf undercoating, and Figure 2 shows the alloy thickness of the same steel plate and the salt spray test ( 3 and 4 are diagrams showing the cycle test conditions of Example Kb. ■ ○ 〈 × Rhinoceros 4g Prisoner H Pak n or Y) → Kure Tsubasa Asahi - Tooth No. 3 @ Zuitsuru Confronting Darkness No. 4 Figure Buifuru @ Darkness

Claims (4)

[Claims] (1) In weight%, C: 0.02% or less Cr: 3-20% Acid-soluble Al: 0.005-0.10% One or more of Ti, Nb, Zr, and V with 0. 03～
On one side of a steel plate containing 0.5% Ni and the remainder consisting of iron and unavoidable impurities, an amount of 0.5 g/m^2 to 5
Corrosion resistance performance characterized by applying a Ni, Ni-Fe alloy base plating layer of g/m^2 and then aluminum plating using an Al-Si plating bath with a Si content of 5 to 13%. A method of manufacturing an aluminized steel plate for fuel exhaust with excellent performance. (2) C in weight%; 0.02% or less Cr; 3 to 20% Acid-soluble Al; 0.005 to 0.10% Ti, Nb, Zr, and one or more of V and 0.03 ~
Ni content of 0.5 g/m^2 to one side of a steel plate containing 0.50% and the remainder consisting of iron and unavoidable impurities.
After applying a Ni or Ni-Fe alloy base plating layer of 5 g/m^2 and applying a Ni or Ni-Fe alloy base plating layer with an Ni content of 0.5 g/m^2 or less on the other side, Si A method for producing an aluminized steel sheet for fuel exhaust with excellent corrosion resistance, characterized by carrying out aluminizing treatment using an Al-Si based plating bath having a content of 5 to 13%. (3) C in weight%; 0.02% or less Cr; 3 to 20% Acid-soluble Al; 0.005 to 0.10% Ti, Nb, Zr, and one or more of V and 0.03 ~
Contains 0.50%, further Ni: 3% or less, Mo: 1
% or less, Cu: 1% or less, on one side of a steel plate containing one or more types, the remainder consisting of iron and inevitable impurities,
Ni amount of 0.5 g/m^2 to 5 g/m^2,
Aluminum plating for fuel exhaust with excellent corrosion resistance, characterized by applying a Ni-Fe alloy base plating layer and then performing aluminum plating using an Al-Si plating bath with a Si content of 5 to 13%. Manufacturing method of steel plate. (4) C in weight%; 0.02% or less Cr; 3 to 20% Acid-soluble Al; 0.005 to 0.10% Ti, Nb, Zr, and one or more of V and 0.03 ~
Contains 0.50%, further Ni: 3% or less, Mo: 1%
Below, Ni
Ni in an amount of 0.5g/m^2 to 5g/m^2, Ni
- After applying a Fe alloy base plating layer and applying a NiNi-Fe alloy base plating layer with a Ni content of 0.5 g/m^2 or less on the other side, Al-S with a Si content of 5 to 13%
A method for producing an aluminized steel sheet for fuel exhaust with excellent corrosion resistance, characterized by carrying out aluminization using an i-series plating bath.