KR20190077753A - Aluminium plated ferritic stainless steel with improved corrosion resistance for water condensation and method for manufacturing the same - Google Patents

Abstract

The present invention relates to ferrite-based stainless steel for an exhaust system of a vehicle, having excellent corrosion resistance of condensate water, and a manufacturing method for the same. According to an embodiment of the present invention, the ferrite-based stainless steel for an exhaust system of a vehicle includes stainless steel base material and an aluminum-plated layer formed on the stainless steel base material. The stainless steel base material includes: 0.01 wt% or less (excluding 0) of C; 0.1-0.5 wt% of Si; 0.5 wt% or less of Mn; 0.035 wt% or less of P; 0.01 wt% or less of S; 11-15 wt% of chrome (Cr); 0.15-0.5 wt% of Ti; 0.013 wt% or less of N; 0.03-0.5 wt% of Sb; 0.05-0.4 wt% of Cu; and residues including Fe and inevitable impurities. A plated compound including Al_17Fe_32Mn_0.8Si_2 (Aluminum iron manganese silicon) and Cu_3Ti_3O (copper titanium oxide) is included between an interface between the stainless steel base material and the aluminum-plated layer.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an aluminum-coated ferritic stainless steel having excellent corrosion resistance against condensation water, and a method for manufacturing the ferritic stainless steel.

The present invention relates to a ferritic stainless steel and a method of manufacturing the ferritic stainless steel, and more particularly, to a ferritic stainless steel for an automobile exhaust system excellent in corrosion resistance against condensation water and a method for manufacturing the ferritic stainless steel.

Among stainless steels, ferritic stainless steel cold rolled products are excellent in high temperature characteristics such as thermal expansion rate and thermal fatigue characteristics, and are resistant to stress corrosion cracking. Accordingly, ferritic stainless steels are widely used in automotive exhaust system parts, household appliances, structures, household appliances, elevators and the like.

Generally, an automobile exhaust system member is divided into a hot part and a cold part according to the temperature of the exhaust gas. Exhaust manifolds, converters and bellows are used for automotive parts of high-temperature materials. These parts are mainly used at a temperature of 600 or higher, and are excellent in high-temperature strength, high-temperature thermal fatigue and high-temperature salt corrosion resistance Should be. On the other hand, a cold part is a member such as a muffler whose operating temperature is less than 400 and which mainly reduces the noise of automobile exhaust gas.

These low temperature members of automobile exhaust system are made of stainless steel (STS) 409, 409L, 439, 436L or Al-plated stainless steel (STS) because of the condensed water corrosion characteristic generated by the sulfur component in automobile fuel, 409 and the like are used, but aluminum-plated stainless steel is used due to discoloration due to high temperature.

For example, STS 409L steel, the cheapest stainless steel among stainless steels, stabilizes carbon (C) and nitrogen (N) to 11% by weight of chromium (Cr) to prevent sensitization of welds, And is mainly used at a temperature of 700 ° C or less. Also, it is the most used steel type because it has some corrosion resistance against the condensed water component generated in the automobile exhaust system.

In countries such as China, Central and South America, and India, where the rate of automobile penetration has increased rapidly, the sulfur content of gasoline components is considerably larger than that of other advanced countries. For example, in Korea and Japan, the content of sulfur (S) in the gasoline component is specified to be 10 ppm or less, but in China, it is specified to be 500 ppm or less. Actually, have.

The sulfur (S) component of the gasoline component is concentrated by the sulfate ion (SO ₄ ^2- ) in the condensed water component of the exhaust gas of the automobile to form corrosive sulfuric acid (H ₂ SO ₄ ) The corrosion resistance can not be secured. As a result, stainless steel materials of chromium (Cr) content of 17% by weight or more and molybdenum (Mo) -containing high chromium (Cr) system such as STS 439 and 436L are gradually applied. However, There is a problem in that it is required to develop a stainless steel material which does not add expensive elements such as chromium (Cr) and molybdenum (Mo), or which has an excellent condensed water corrosion resistance and an excellent surface appearance by adding only trace elements.

Embodiments of the present invention provide a ferritic stainless steel for an automobile exhaust system having excellent corrosion resistance against condensation water and a method for manufacturing the ferritic stainless steel.

A ferritic stainless steel for an automobile exhaust system excellent in corrosion resistance against condensation water according to an embodiment of the present invention is characterized by containing C: 0.01% or less (excluding 0), Si: 0.1 to 0.5%, Mn: 0.5% : Not more than 0.035%, S: not more than 0.01%, chromium (Cr): 11 to 15%, Ti: 0.15 to 0.5%, N: not more than 0.013%, Sb: 0.03 to 0.5% A stainless steel base material containing iron (Fe) and other unavoidable impurities, and an aluminum plated layer formed on the stainless steel base material, wherein the interface between the stainless steel base material and the aluminum plated layer is composed of Al ₁₇ Fe ₃₂ Mn _{0 . 8} Si ₂ (Aluminum Iron Manganese Silicon) and Cu ₃ Ti ₃ O (Copper Titanium Oxide).

The Sb may be 0.07 to 0.15%.

The Cu may be 0.07 to 0.3%.

Further, Sb may be concentrated on the surface portion of the stainless steel base material adjacent to the aluminum plating layer by 9 times or more as compared with the entire stainless steel base material.

Also, when evaluating the corrosion characteristics of the condensate, the maximum official depth may be less than 0.3 mm.

The threshold current density in the 5% sulfuric acid atmosphere may be 8 mA or less, and the formula potential may be 144 mV or more.

A method for manufacturing a ferritic stainless steel for an automobile exhaust system having excellent corrosion resistance against condensation water according to an embodiment of the present invention is characterized by containing 0.01% or less of C (excluding 0), 0.1 to 0.5% of Si, 0.5% or less of Mn , P: not more than 0.035%, S: not more than 0.01%, chromium (Cr): 11 to 15%, Ti: 0.15 to 0.5%, N: not more than 0.013%, Sb: 0.03 to 0.5% And the remainder is a step of producing a slab containing iron (Fe) and other unavoidable impurities, hot rolling the slab, cold-rolling the hot-rolled steel sheet, and applying the aluminum plate to the cold- ≪ / RTI >

The hot rolling is reheated at a temperature in the range of 1100 to 1200 占 폚, hot-rolled, and hot-rolled and annealed in a temperature range of 900 to 1100 占 폚. The cold rolling is carried out at a reduction ratio of 60% It is possible to perform cold-rolling annealing in a temperature range.

According to the embodiment of the present invention, copper (Cu) and antimony (Sb) are added to stainless steel corresponding to 11 to 14% by weight of conventional chromium (Cr) in the conventional ferritic stainless steel at a silicon (Si) By weight or more based on the total weight of the ferritic stainless steel.

Accordingly, the ferritic stainless steel according to the embodiment of the present invention can be used as a low-temperature member for an exhaust system such as a muffler for an automobile exhaust system, and can be used in an area of China including a large amount of sulfur (S) It is possible to manufacture a component for an automobile exhaust system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the maximum depth of a concrete in a corrosion solution of an exhaust pipe of an automobile exhaust system of a stainless steel to which copper (Cu) and antimony (Sb) are added according to the present invention and an unused stainless steel.
FIG. 2 is a graph showing the relationship between an interface between stainless steel and an aluminum (Al) plated layer of stainless steel to which copper (Cu) and antimony (Sb) is added according to an embodiment of the present invention and transmission electron microscopy (TEM) energy-dispersive spectroscopy ). Fig.
FIG. 3 is a diagram showing the result of analysis of the base material of stainless steel to which copper (Cu) and antimony (Sb) are added by transmission electron microscopy (TEM) EDS (Energy-Dispersive Spectroscopy) according to an embodiment of the present invention.
4 shows the results of X-ray diffraction (XPD) analysis of the interface between the aluminum (Al) plating layer and the stainless steel base material of stainless steel to which copper (Cu) and antimony (Sb) were added according to an embodiment of the present invention Graph.
5 is a graph showing the results of X-ray diffraction (XPD) analysis of stainless steel after peeling off an aluminum (Al) plating layer of stainless steel to which copper (Cu) and antimony (Sb) were added according to an embodiment of the present invention. to be.
FIG. 6 is a graph showing the results of X-ray diffraction (XPD) analysis of the interface between the aluminum (Al) plating layer and the stainless steel base material of stainless steel to which copper (Cu) and antimony (Sb) were not added.

The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

The singular forms " a " include plural referents unless the context clearly dictates otherwise.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. First, the ferritic stainless steel will be described, and then the ferritic stainless steel will be described.

The inventors of the present invention have obtained the following findings through concrete study on the effect of the trace elements on the corrosion resistance of high purity ferritic stainless steels, especially Cu and Sb.

A ferritic stainless steel for an automobile exhaust system according to an embodiment of the present invention comprises 0.01% or less of C, 0.1 to 0.5% of Si, 0.5% or less of Mn, 0.035% or less of P, 0.01% or less of S, , And the balance Fe and other unavoidable impurities are contained in an amount of 0.1 to 15% Cr, 0.15 to 0.5% of Ti, 0.013% or less of N, 0.05 to 0.5% of Sb and 0.05 to 0.5% of Cu.

Hereinafter, the reason for limiting the numerical value of the content of the component component in the embodiment of the present invention will be described. Unless otherwise stated, the unit is wt%.

The content of C is 0.01% or less.

The content of N is 0.013% or less.

Carbon (C) and nitrogen (N) present intrinsically as Ti (C, N) carbonitride forming elements do not form carbonitride of Ti (C, N) do. C and N present in the solid solution lower the elongation and low-temperature impact characteristics of the material, and chromium carbide (C ₆ Cr ₂₃ ) is generated when the material is used for a long time at 600 ° C or less after welding, May be limited to 0.01% in case of C and 0.013% in case of N.

Also, if the content of C and N is increased (C + N), when the Ti content is high, surface defects such as scab are generated due to increase of rigid inclusions, And the elongation and impact characteristics due to the increase in solid solution C and N are lowered. It is therefore desirable to limit the content of (C + N) to 0.02% or less.

The content of Si is 0.1 to 0.5%.

Silicon (Si) is an element to be added as a deoxidizing agent, and it is preferably added at 0.1% or more to improve the stability of the ferrite phase and improve the formaldehyde and oxidation resistance characteristics with the ferrite phase forming element. However, when the content is excessive, problems such as an increase in rigid Si inclusions and surface defects may occur, so that the upper limit can be limited to 0.5%.

The content of Mn is 0.5% or less.

When the content of manganese (Mn) is increased, deposits such as manganese sulfide (MnS) are formed to lower the pitting resistance. However, if the content of Mn is too small, it may cause an increase in purification cost, etc., and therefore it is preferable to control the content of manganese (Mn) to 0.5% or less.

The content of P is 0.035% or less.

The content of S is 0.01% or less.

The phosphorus (P) and sulfur (S) form intergranular segregation and manganese sulfide (MnS) precipitates to lower the hot workability. However, excessive reduction of P and S causes an increase in purification cost and the like, so it is preferable to limit the upper limit to 0.035% for P and to 0.01% for S.

The content of Cr is 11 to 15%.

Chromium (Cr) is the element that is the largest element among the elements for improving the corrosion resistance of stainless steel and is preferably added in an amount of 11% or more for the purpose of manifesting corrosion resistance in a condensed atmosphere. However, when the content is excessive, corrosion resistance and the like are improved, but the strength is high, the elongation and impact are reduced, the effect of adding trace elements (Cu, Sb) is not obtained and the manufacturing cost is increased. Can be limited.

The content of Ti is 0.15 to 0.5%.

Titanium (Ti) is an element that prevents the occurrence of intergranular corrosion by fixing carbon and nitrogen, and when the ratio of Ti / (C + N) is low, corrosion resistance may be deteriorated due to grain boundary corrosion. Accordingly, Ti is preferably added in an amount of 0.15% or more. However, when the content is excessive, surface inclusions such as scabs are generated due to an increase in rigid inclusions, and nozzle clogging occurs during performance, so that the upper limit can be limited to 0.5%.

The content of Sb is 0.03 to 0.5%.

Antimony (Sb) is an essential element for ensuring formal resistance and sulfuric acid corrosion resistance, and it is preferable to add 0.03%. More preferably, the minimum content of Sb can be limited to 0.05%. However, if the content is excessive, a problem may arise in the progress of the manufacturing process, and the upper limit may be limited to 0.5%. More preferably, the content of Sb can be controlled to 0.07 to 0.15%.

The content of Cu is 0.05 to 0.5%.

Copper (Cu) is an indispensable element for ensuring corrosion resistance of condensate, and it is preferable to add 0.05% or more in order to secure the resistance to formaldehyde and the resistance to sulfuric acid. However, if the content is excessive, problems may occur in cost increase and manufacturing process progress, so that the upper limit can be limited to 0.5%. More preferably, the content of Cu can be controlled to 0.07 to 0.3%.

The ferritic stainless steel according to an embodiment of the present invention may be an aluminum (Al) plated ferritic stainless steel, which includes a stainless steel base material and an aluminum plated layer formed on the stainless steel base material.

The ferritic stainless steel according to one embodiment of the present invention is characterized in that the interface between the stainless steel base material and the aluminum plating layer is composed of Al ₁₇ Fe ₃₂ Mn _{0 . 8} Si ₂ (Aluminum Iron Manganese Silicon) and Cu ₃ Ti ₃ O (Copper Titanium Oxide).

In the ferritic stainless steel according to an embodiment of the present invention, antimony (Sb) is concentrated 9 times or more in the surface portion of the base material of the stainless steel adjacent to the aluminum plating layer as compared with the entire stainless steel base material. Antimony (Sb) can be concentrated on the surface of a stainless steel in which oxidation scale is relatively strong due to stronger oxygen affinity than other elements.

The ferritic stainless steel according to an embodiment of the present invention not only has a region in which antimony (Sb) is concentrated in the surface portion but also has an area of Al ₁₇ Fe ₃₂ Mn ₀ .05 in the interface between the stainless steel base material and the aluminum plating layer _. Compared to ferritic stainless steels which do not contain copper (Cu) and antimony (Sb) or which are not concentrated on the surface, including ₈ Si ₂ (Aluminum Iron Manganese Silicon) and Cu ₃ Ti ₃ O (Copper Titanium Oxide) The desired improved condensation water corrosion resistance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the maximum depth of a concrete in a corrosion solution of an exhaust pipe of an automobile exhaust system of a stainless steel to which copper (Cu) and antimony (Sb) are added according to the present invention and an unused stainless steel. 1 is a ferritic stainless steel in which copper (Cu) and antimony (Sb) are added to an aluminum-plated ferritic stainless steel according to an embodiment of the present invention, and a comparative example is a conventional aluminum (Al) The maximum depth of the concrete after the evaluation of the corrosion characteristics of the condensate.

For example, the ferritic stainless steel according to an embodiment of the present invention may have a maximum formal depth of 0.3 mm or less in evaluating the corrosion property of the condensed water. In contrast, conventional Al-coated 409L steels exhibit a maximum formal depth of greater than about 0.47 mm.

The ferritic stainless steel according to one embodiment of the present invention can be manufactured by a general method of manufacturing a steel sheet composed of a ferritic stainless steel.

For example, molten steel having the above composition is refined by the AOD method or the VOD method. Then, molten steel may be produced by a conventional method to produce a slab, followed by hot rolling, hot rolling, pickling, cold rolling, finish annealing, and pickling.

Specifically, the slab may be manufactured by continuously casting molten steel satisfying the above composition, and then subjected to hot rolling, hot rolling, cold rolling, and cold rolling and annealing. Such a manufacturing process may be a conventional STS 409L manufacturing process .

Hot rolling can be performed by reheating the slab at a temperature range of 1,100 to 1,200 ° C. In the present invention, the higher the reheating temperature of the slab is, the more advantageous for recrystallization during hot rolling. However, if the reheating temperature is too high, surface defects will be frequent and if the slab heating temperature is low, surface defects will be generated. can do.

The hot-rolled steel sheet can be hot-rolled and annealed in a temperature range of 900 to 1,100 ° C.

Followed by cold rolling at a reduction ratio of 60% or more. If the cold reduction rate is low, it is difficult to remove surface defects and to secure surface characteristics. On the other hand, if the cold reduction rate is high, it is preferable to improve the workability by increasing the r-bar value.

The cold-rolled steel sheet can be cold-annealed in a temperature range of 800 to 900 占 폚. Thereafter, the cold-rolled steel sheet may be subjected to an aluminum plating process to produce an Al-coated ferrite-based stainless steel.

The method of manufacturing ferritic stainless steel according to an embodiment of the present invention may further include a step of heat-treating aluminum (Al) plated ferritic stainless steel at a temperature of 300 to 500 ° C within 48 hours.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example  One

The ferritic stainless steel prepared as in the developed steel of Table 1 below was dissolved in a 50 Kg vacuum melting plant to prepare a 120 mm thick slab. The prepared slab was hot-rolled in a temperature range of 1100 to 1200 캜 to prepare a hot-rolled steel sheet having a thickness of 3.0 mm. Thereafter, the hot-rolled steel sheet was annealed, pickled, cold-rolled to produce a cold-rolled steel sheet having a thickness of 1.2 mm, subjected to finish annealing, and subjected to a pickling process to perform aluminum (Al) plating.

Example  2

Was prepared in the same manner as in Example 1, except that the composition of Example 2 in the following [Table 1] was used.

Comparative Example

Were prepared in the same manner as in Example 1, except that the compositions of Comparative Examples 1 to 8 in the following [Table 1] were used.

division C Si Mn P S Al Ni Cr Ti N Sb Cu Example 1 dog
foot
River 0.005 0.25 0.27 0.005 0.002 0.034 0.10 11 0.200 0.0070 0.1 0.3 Example 2 0.005 0.25 0.27 0.005 0.002 0.034 0.10 14 0.200 0.0070 0.1 0.3 Comparative Example 1 ratio
School
River 0.005 0.25 0.27 0.005 0.002 0.034 0.10 11 0.200 0.0070 0.1 0 Comparative Example 2 0.005 0.25 0.27 0.005 0.002 0.034 0.10 11 0.200 0.0070 0 0 Comparative Example 3 0.005 0.25 0.27 0.005 0.002 0.034 0.10 11 0.200 0.0070 0 0.3 Comparative Example 4 0.005 0.25 0.27 0.005 0.002 0.034 0.10 11 0.200 0.0070 0.02 0.4 Comparative Example 5 ratio
School
River 0.005 0.25 0.27 0.005 0.002 0.034 0.10 14 0.200 0.0070 0.1 0 Comparative Example 6 0.005 0.25 0.27 0.005 0.002 0.034 0.10 14 0.200 0.0070 0 0.3 Comparative Example 7 0.005 0.25 0.27 0.005 0.002 0.034 0.10 14 0.200 0.0070 0 0 Comparative Example 8 0.005 0.25 0.27 0.005 0.002 0.034 0.10 14 0.200 0.0070 0.02 0.38

The corrosion resistance was evaluated according to the Japanese standard JASO-B M611-92 for condensate corrosion resistance. I.e., Cl ^- concentration: 100ppm, NO ₃ ^- concentration ^- the 80 ℃ in an aqueous solution of 8.0 ± 0.2: Concentration _{600pmm, CH 3 COO:: 800pmm} , pH 20pmm, SO 3 2- concentration: 600pmm, SO ₄ ^2- concentration The maximum official depth was measured after repeating a total of 4 cycles with a cycle of 24 hours holding at 250 < 0 > C for 24 hours.

The corrosion resistance of the stainless steel according to the above Examples and Comparative Examples 1-3 and 5-7 was evaluated according to the above method, and the maximum depth (mm) was measured and shown in Table 2 below.

division 11Cr 14Cr Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 2 Comparative Example 5 Comparative Example 6 Comparative Example 7 Maximum formula depth (mm) 0.292 0.427 0.471 0.372 0.272 0.362 0.326 0.378

The maximum current density and the formula potential of ferrite stainless steels in the sulfuric acid atmosphere of Examples and Comparative Examples were measured and shown in Table 3 below.

5% H ₂ SO ₄ aqueous solution, temperature condition The anodic polarization characteristics of the stainless steel were measured at 30 ° C. The corrosion resistance after the test was evaluated by the maximum corrosion current density in the active area. In addition, the formal resistance was measured at a Cl ^- concentration of 1% solution and a temperature condition of 30 ° C.

Critical current density
(mA / cm ² ) Official potential
(mV) Example 1 8 144 Example 2 5 187 Comparative Example 1 40 119 Comparative Example 3 32 125 Comparative Example 5 24 142 Comparative Example 7 18 159

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the maximum depth of a concrete in a corrosion solution of an exhaust pipe of an automobile exhaust system of a stainless steel to which copper (Cu) and antimony (Sb) are added according to the present invention and an unused stainless steel.

Referring to FIGS. 1 and 2, ferritic stainless steels according to an embodiment of the present invention exhibit a corrosion resistance of about 0.292 mm when the maximum official depth is 11% of chromium (JASO-B M611-92) And 0.272 mm when chromium is contained by 14%. On the contrary, the maximum official depths of conventional aluminum (Al) -plated 409L steel are 0.471mm and 0.378mm, respectively.

Accordingly, it can be confirmed that the corrosion resistance of the condensed water is improved in the case of aluminum (Al) plated stainless steel to which copper (Cu) and antimony (Sb) are added according to the embodiments of the present invention.

Also, referring to Table 3, in the case of Examples 1 and 2 which satisfied both the copper (Cu) and antimony (Sb) contents, the critical current density was measured as low as 8 mA / cm ² and 5 mA / cm ² .

In the case of copper, only one of Comparative Examples 1 and 5, addition of antimony (Sb) without the addition of (Cu), the critical current density were measured respectively as high as ^{40mA / cm 2, 24mA / cm} 2.

In Comparative Example 3 in which the content of chromium (Cr) was as low as 11% by weight and only copper (Cu) was added without adding antimony (Sb), the critical current density was as high as ³² mA / cm ² .

As shown in Table 3, it was found that the embodiments in which copper (Cu) and antimony (Sb) were both added decreased the critical current density and the sulfuric acid corrosion resistance by increasing the formal potential compared with the comparative examples.

The ferritic stainless steel according to one embodiment of the present invention is critical corrosion current density in the automotive exhaust system condensate solution is 8mA / cm ^r Or less, and the formal potential may be 144 mV or more.

FIG. 2 and FIG. 3 are schematic cross-sectional views showing the interface between an aluminum (Al) plated layer of stainless steel and a stainless steel base material to which copper (Cu) and antimony (Sb) are added according to an embodiment of the present invention, , TEM) and Energy-Dispersive Spectroscopy (EDS).

Table 4 below shows measurement results of major components in the surface layer concentrated layer of the stainless steel base material and the stainless steel base material adjacent to the aluminum plating layer according to one embodiment of the present invention.

Element (wt.%) Interface Base material Fe 75.39 88.52 Cr 11.01 10.69 Al 10.12 0.07 Si 2.21 0.34 Sb 0.93 0.11 Cu 0.34 0.26 Total 100 100

 In the ferritic stainless steel according to one embodiment of the present invention, copper (Cu) and antimony (Sb) on the surface portion of the stainless steel base material adjacent to the aluminum plating layer are 1.5 times and 9 times It can be confirmed that it is concentrated more than twice.

4 shows the results of X-ray diffraction (XPD) analysis of the interface between the aluminum (Al) plating layer and the stainless steel base material of stainless steel to which copper (Cu) and antimony (Sb) were added according to an embodiment of the present invention Graph.

As shown in FIG. 4, the surface of the stainless steel base material and the aluminum plating layer was coated with Al ₁₇ Fe ₃₂ Mn _{0 . 8} Si ₂ (Aluminum Iron Manganese Silicon), and Al (Aluminum).

5 is a graph showing the results of X-ray diffraction (XPD) analysis of stainless steel after peeling off an aluminum (Al) plating layer of stainless steel to which copper (Cu) and antimony (Sb) were added according to an embodiment of the present invention. to be.

Referring to FIG. 5, it can be confirmed that Cu ₃ Ti ₃ O (Copper Titanium Oxide) is included as a plating compound at the interface between the stainless steel base material and the aluminum plating layer.

FIG. 6 is a graph showing the results of X-ray diffraction (XPD) analysis of the interface between the aluminum (Al) plating layer and the stainless steel base material of stainless steel to which copper (Cu) and antimony (Sb) were not added.

As shown in FIG. 6, the interface between the stainless steel base material and the aluminum (Al) plating layer is composed of Al ₁₇ Fe ₃₂ Mn _{0 . 8} Si ₂ (Aluminum Iron Manganese Silicon) and Cu ₃ Ti ₃ O (Copper Titanium Oxide) are not formed.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited thereto. Those skilled in the art will recognize that other embodiments may occur to those skilled in the art without departing from the scope and spirit of the following claims. It will be understood that various changes and modifications may be made.

Claims (8)

(C): 0.01% or less (excluding 0), Si: 0.1 to 0.5%, Mn: 0.5% or less, P: 0.035% or less, S: 0.01% The balance being a stainless steel base material containing 0.15 to 0.5% of Ti, 0.013% or less of N, 0.03 to 0.5% of Sb, 0.05 to 0.4% of Cu and the balance of Fe and other unavoidable impurities, In a ferritic stainless steel comprising an aluminum plated layer formed,
And a plating compound including Al ₁₇ Fe ₃₂ Mn _0.8 Si ₂ (Aluminum Iron Manganese Silicon) and Cu ₃ Ti ₃ O (Copper Titanium Oxide) at the interface between the stainless steel base material and the aluminum plating layer Ferritic stainless steel for automobile exhaust system. The method according to claim 1,
Ferritic stainless steel for automobile exhaust systems excellent in condensation water corrosion resistance, wherein Sb is 0.07 to 0.15% by weight. The method according to claim 1,
The ferritic stainless steel according to claim 1, wherein the Cu is 0.07 to 0.3% by weight, and the corrosion resistance of the ferritic stainless steel is excellent. 3. The method according to claim 1 or 2,
Wherein the stainless steel base material adjacent to the aluminum plating layer has a concentration of Sb of at least 9 times higher than that of the stainless steel base material as compared with the entire surface of the stainless steel base material, and exhibits excellent corrosion resistance against corrosion of the ferritic stainless steel. 3. The method according to claim 1 or 2,
Ferritic stainless steel for automotive exhaust systems with excellent corrosion resistance of condensate with a maximum formal depth of less than 0.3mm when assessing condensate corrosion characteristics. 3. The method according to claim 1 or 2,
Ferritic stainless steels for automotive exhaust systems that have a critical current density of 8 mA or less in a 5% sulfuric acid atmosphere, and excellent corrosion resistance of a condensate with a formal potential of 144 mV or more. (C): 0.01% or less (excluding 0), Si: 0.1 to 0.5%, Mn: 0.5% or less, P: 0.035% or less, S: 0.01% 0.1 to 0.5% of Ti, 0.013% or less of N, 0.03 to 0.5% of Sb, 0.05 to 0.4% of Cu, and the balance of Fe and other unavoidable impurities;
Hot rolling the slab;
Cold rolling the hot-rolled steel sheet; And
And performing aluminum plating on the cold-rolled steel sheet. The method of manufacturing a ferritic stainless steel for an automobile exhaust system having excellent resistance to condensation water corrosion. 8. The method of claim 7,
The hot-rolling is reheated to a temperature range of 1100 to 1200 ° C, hot-rolled, and hot-rolled and annealed in a temperature range of 900 to 1100 ° C .; the cold-rolling is progressed at a reduction ratio of 60% Which is excellent in corrosion resistance of sulfuric acid.

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