KR101787283B1 - Steel having excellent corrosion resistance and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a corrosion resistant steel with condensate corrosion resistance having excellent corrosion resistance against condensate of an exhaust gas of an internal combustion engine; and a manufacturing method thereof. According to one embodiment of the present invention, the corrosion resistant steel includes an alloy composition comprising: 0.01-0.10 wt% of carbon (C); 0.01-0.50 wt% of silicon (Si); 0.05-0.15 wt% of manganese (Mn); greater than zero to 0.18 wt% of phosphorus (P); greater than zero to 0.02 wt% of sulfur (S); 0.001-0.01 wt% of niobium (Nb); 0.10-0.30 wt% of copper (Cu); 0.001-0.5 wt% of nickle (Ni); 0.005-0.12 wt% of antimony (Sb); 0.005-0.12 wt% of tin (Sn); and the remainder consisting of iron (Fe) and inevitable impurities. Moreover, the corrosion resistant steel has a tensile strength (TS) of 340-450 MPa, a yield strength (YS) of 200-350 MPa, and an elongation ratio of 30-45%.

Description

TECHNICAL FIELD [0001] The present invention relates to a corrosion resistant steel having corrosion resistance of condensate and a method of manufacturing the corrosion resistant steel. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a corrosion resistant steel having corrosion resistance against condensed water and a method for producing the same, and more particularly to a corrosion resistant steel having excellent sulfuric acid resistance, acid resistance and hydrochloric acid resistance, excellent weldability and component formability, And more particularly, to a corrosion resistant steel for an automobile exhaust system excellent in corrosion resistance against condensation water which can prevent galvanic corrosion caused by contact with metal parts and a manufacturing method thereof.

An internal combustion engine using fossil fuel is provided with a separate exhaust device for exhausting the exhaust gas generated after combustion. For example, an automobile has an exhaust system such as a muffler system to exhaust exhaust gas generated during traveling. The exhaust system in the high-temperature exhaust gas is condensed in accordance with the change in the surrounding environment such as temperature and humidity can cause the condensate, the condensate is a sulfide in the exhaust gas (SO _x), chlorides (Cl), nitride (NO _x ) And the like, and strong acids such as sulfuric acid, hydrochloric acid, and nitric acid.

Such a strong acidic substance promotes corrosion of an automobile exhaust system and serves as a main factor for lowering the durability lifetime. Therefore, stainless steel used in an internal combustion engine such as a power plant has been used for corrosion prevention.

On the other hand, the exhaust apparatus of an automobile is more varied in operating temperature and exposure environment than the exhaust apparatus of the power plant due to the nature of the fuel and the exposed environment, the condensed water contains more various kinds of acidic substances, have.

In recent years, there has been a demand for development of corrosion resistant steel having excellent strength and formability, while being able to substitute stainless steel having a high production cost because of high content of alloy element, .

A related prior art document is Korean Patent Laid-Open Publication No. 10-2010-0101730, which discloses sulfuric acid corrosion resistant steel and a method for producing the same.

It is an object of the present invention to provide a steel sheet which is excellent in sulfuric acid resistance, acid fastness and hydrochloric acid resistance, excellent in weldability and part formability, excellent in sound insulation and capable of inhibiting galvanic corrosion, Which is excellent in corrosion resistance against exhaust gas condensed water of an internal combustion engine, is excellent in economy and productivity, and a method for producing the corrosion resistant steel.

An embodiment of the present invention is a method of manufacturing a semiconductor device comprising the steps of: 0.001 wt% to 0.10 wt% of carbon; 0.01 wt% to 0.50 wt% of silicon; 0.05 wt% to 0.15 wt% of manganese; (Ni): 0.001 to 0.01 wt.%, Cu: 0.10 to 0.30 wt.%, Ni (Ni) : 0.001 wt.% To 0.5 wt.%, Antimony (Sb): 0.005 wt.% To 0.12 wt.%, Tin (Sn): 0.005 wt.% To 0.12 wt.% And balance of iron (Fe) and other unavoidable impurities. A tensile strength (TS) of 340 MPa to 450 MPa, a yield strength (YS) of 200 MPa to 350 MPa and an elongation of 30% to 45%.

The content of silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), niobium (Nb), copper (Cu), nickel (Ni), antimony (Sb) and tin And the total amount of antimony (Sb) and tin (Sn) may be 0.005 wt% to 0.20 wt%.

The corrosion resistant steel having the corrosion resistance of the condensate may have a corrosion rate (CR) value of 60 mm / year or less.

The weight ratio of copper (Cu): antimony (Sb) in the alloy composition may be 2 to 3.5: 0.5 to 1.

Another embodiment of the present invention is a method of hot rolling a slab comprising the above-described alloy composition; And cold-rolling the steel to a corrosion resistant steel having a corrosion resistance of condensed water.

The hot rolling step may include heating the slab at SRT: 950 ° C to 1,250 ° C, finishing rolling at 800 ° C to 950 ° C, shearing at CT, and winding at 100 ° C to 740 ° C have.

The cold rolling step comprises pickling the hot-rolled steel at 75 to 85 ° C with hydrochloric acid having a concentration of 17% to 90%, subjecting the hot-rolled steel to cold rolling at a reduction ratio of 50% to 80% Annealing, and annealing.

The present invention is to provide a steel sheet which is excellent in sulfuric acid resistance, acid resistance and hydrochloric acid resistance, excellent in weldability and part formability, excellent in sound insulation, can inhibit galvanic corrosion occurring in contact with other metal parts, Corrosion resistance to exhaust gas condensed water of an internal combustion engine is excellent, and a corrosion resistant steel having excellent economy and productivity and a method of manufacturing the corrosion resistant steel can be provided.

1 is a flowchart of a corrosion resistant steel manufacturing method according to an embodiment of the present invention.
2 is a flowchart of a hot rolling step in a corrosion resistant steel making method according to an embodiment of the present invention.
3 is a flowchart of a cold rolling step in a corrosion resistant steelmaking method according to an embodiment of the present invention.
4 shows the corrosion resistance evaluation results of the specimens of Example 1 of the present invention and Comparative Examples 1 and 2.
Fig. 5 shows the degree of hydrogen generation in the immersion liquid for the specimens of Example 1 and Comparative Example 1. Fig.

<Condensation Corrosion Resistant Corrosion resistant steel >

An embodiment of the present invention is a method of manufacturing a semiconductor device comprising the steps of: 0.001 wt% to 0.10 wt% of carbon; 0.01 wt% to 0.50 wt% of silicon; 0.05 wt% to 0.15 wt% of manganese; (Ni): 0.001 to 0.01 wt.%, Cu: 0.10 to 0.30 wt.%, Ni (Ni) : 0.001 wt.% To 0.5 wt.%, Antimony (Sb): 0.005 wt.% To 0.12 wt.%, Tin (Sn): 0.005 wt.% To 0.12 wt.% And balance of iron (Fe) and other unavoidable impurities. And having a tensile strength (TS) of 340 MPa to 450 MPa, a yield strength (YS) of 200 MPa to 350 MPa and an elongation of 30% to 45%.

Accordingly, it is an object of the present invention to provide a method for producing a steel sheet which is excellent in sulfuric acid resistance, acid fastness and hydrochloric acid resistance, excellent in weldability and part formability, excellent in sound insulation and capable of inhibiting galvanic corrosion, It is possible to provide a corrosion resistant steel excellent in corrosion resistance against exhaust gas condensed water of an internal combustion engine, slow in corrosion rate, and excellent in economy and productivity.

Further, the corrosion resistant steel of the present invention can be used for automobile parts. More specifically, the automobile part may be a part for an automobile exhaust system, and more specifically, a part applicable to a muffler system, for example, an automobile baffle, a pipe, an inner shell, and the like.

In addition, the corrosion resistant steel of the present invention is excellent in sound insulation and is more excellent in reducing the vibration sound of the engine, the impact sound of the road surface, and the noise due to the separation when applied to components for an automobile exhaust system.

The corrosion-resistant steel having corrosion resistance against condensation water of the present invention produces condensed water in a complicated corrosive environment including nitric acid, hydrochloric acid and the like in addition to sulfuric acid and provides better corrosion resistance to an automotive exhaust apparatus having a variable running condition , It is possible to realize various high quality appearance and excellent moldability. Particularly, in such applications, the corrosion-resistant steel of the present invention can be supplied at a manufacturing cost of about 20% to 70% of that of the conventional stainless steel, so that it is very economical and the lifetime of parts can be equal to or better than that of the prior art.

Hereinafter, the components included in the alloy composition of the corrosion resistant steel having the corrosion resistance of the condensed water of the present invention will be described in detail.

Carbon (C)

Carbon (C) contributes to strength improvement and affects the elongation and weldability of the steel.

The carbon is added in an amount of 0.001 wt% to 0.10 wt% of the total weight of the corrosion resistant steel. When the addition amount of carbon is less than 0.001% by weight, it is difficult to secure sufficient strength. On the other hand, when the carbon content exceeds 0.10 wt%, the corrosion resistance, toughness and weldability are deteriorated.

Silicon (Si)

Silicon (Si) serves as a deoxidizer and contributes to improving strength and elongation.

The silicon is added in an amount of 0.01 wt% to 0.50 wt% of the total weight of the corrosion resistant steel. When the addition amount of silicon is less than 0.01% by weight, the effect of the addition is insufficient and it is difficult to secure the elongation. Conversely, when the addition amount of silicon exceeds 0.50% by weight, the corrosion characteristics for the sulfuric acid treatment test at a concentration of 70% at 1% to 40% may be reduced in proportion to the silicon content.

Manganese (Mn)

Manganese (Mn) precipitates the solid sulfur (S) into manganese sulfide, which can prevent the embrittlement of embrittlement due to solid sulfur and increase the strength.

The manganese is added in an amount of 0.05 wt% to 0.15 wt% of the total weight of the corrosion resistant steel. When the content of manganese is less than 0.05% by weight, the effect of the addition is insufficient and it is difficult to secure strength. On the other hand, when the content of manganese exceeds 0.15% by weight, manganese bands develop at the center of the material thickness to lower the elongation rate, which may cause cracks or wrinkles in the corrosion resistant steel, and the sound insulation may be deteriorated.

In (P)

Phosphorus (P) contributes to the improvement of the strength of the corrosion resistant steel by solid solution strengthening, and as an element effective for suppressing the formation of carbide, it can play a role of preventing elongation decrease due to carbide formation upon annealing.

In the present invention, the content of phosphorus is limited to more than 0 to 0.18% by weight of the total weight of the corrosion resistant steel. When phosphorus (P) is added in an amount exceeding 0.18 wt%, the corrosion characteristics for the sulfuric acid treatment test at a concentration of 1% to 40% at 70 캜 can be reduced in proportion to the content of phosphorus (P) Can not be implemented.

Sulfur (S)

Sulfur (S) contributes partly to the strength improvement, but when added in excess, toughness and weldability are impaired and MnS nonmetallic inclusions are increased to inhibit the incombustibility effect of Mn and cause processing cracks. In addition, it contributes to the formation of the FeSO ₄ film, thereby further improving the corrosion resistance.

In the present invention, the content of sulfur is limited to more than 0 to 0.02% by weight of the total weight of the corrosion resistant steel. In this case, the corrosion characteristics for the low concentration sulfuric acid treatment test of 1% to 10% can be improved in proportion to the content of sulfur (S). However, when the sulfur (S) content exceeds 0.02% by weight, the corrosion resistance may decrease in proportion to the sulfur (S) content.

Niobium ( Nb )

Niobium (Nb) is an element that improves strength and toughness without deteriorating corrosion resistance.

Niobium (Nb) is added in an amount of 0.001 wt% to 0.01 wt% of the total weight of the corrosion resistant steel. When the content of niobium (Nb) is less than 0.001% by weight, the effect of improving strength and toughness is insufficient and the sound insulation may be deteriorated. On the other hand, if it exceeds 0.01% by weight, deterioration in toughness of the weld heat affected zone may occur excessively.

Copper (Cu)

Copper (Cu) contributes to solid solution strengthening and enhances strength. Copper (Cu) is converted to copper oxide to stabilize FeSO ₄ , Fe ₂ O ₃ , and Fe ₃ O ₄ to increase the barrier effect on the surface scale and to have a potential higher than the hydrogen reduction potential Improves corrosion resistance.

The copper (Cu) is added in an amount of 0.1 wt% to 0.3 wt% of the total weight of the corrosion resistant steel. If the copper (Cu) content is less than 0.1% by weight, the effect of the addition is insufficient. On the other hand, if copper (Cu) is added in an amount exceeding 0.3 wt%, the corrosion rate is drastically lowered, and the corrosion resistance improvement effect is less than the increase of the addition amount, so that the economical efficiency is low.

nickel( Ni )

Nickel (Ni) contributes to improving the incombustibility and can further improve toughness and weldability.

The nickel (Ni) is added in an amount of 0.001 wt% to 0.5 wt% of the total weight of the corrosion resistant steel. If the addition amount of nickel (Ni) is less than 0.001% by weight, the effect of addition is insufficient. On the other hand, when the added amount of nickel (Ni) exceeds 0.5% by weight, corrosion resistance and toughness may be deteriorated.

antimony( Sb )

Antimony (Sb) contributes to improvement of the incombustibility and can further improve resistance to corrosion by sulfuric acid having a concentration of 1% to 40%. In particular, antimony (Sb) precipitates on the surface of the steel to form a film, and serves to control the anode. At the same time, it increases the low hydrogen overvoltage of iron, which contributes to the control of the negative electrode which suppresses the corrosion of iron generated by consuming electrons from the anode by hydrogen. That is, antimony lowers the overall corrosion rate and improves the corrosion resistance through the anode control and the cathode control.

The antimony (Sb) is added in an amount of 0.005 wt% to 0.12 wt% of the total weight of the corrosion resistant steel. When the addition amount of antimony (Sb) is less than 0.005% by weight, the effect of addition is insufficient. On the other hand, if the addition amount of antimony (Sb) exceeds 0.12% by weight, it may be concentrated on the surface of the steel to cause surface defects and cause liquid metal brittleness (LME) have.

Tin (Sn)

Tin (Sn) contributes to improvement in entanglement with the copper as an austenite stabilizing element. In addition, tin (Sn) mainly suppresses the consumption of electrons at the cathode, thereby lowering the overall corrosion rate and improving the sulfuric acid corrosion resistance. In particular, tin (Sn) works in combination with antimony (Sb) to increase the low hydrogen overvoltage of iron, thereby suppressing corrosion of iron caused by hydrogen consuming electrons from the negative electrode.

The tin (Sn) is added in an amount of 0.005 wt% to 0.12 wt% of the total weight of the corrosion resistant steel. If the addition amount of tin (Sn) is less than 0.005% by weight, the effect of addition is insufficient. On the other hand, if the addition amount of tin (Sn) exceeds 0.12 wt%, the toughness of the corrosion resistant steel may be deteriorated.

The alloy composition comprises the balance iron (Fe) and other unavoidable impurities. The present invention is to provide a method for producing a steel product which is excellent in sulfuric acid resistance, acid resistance and hydrochloric acid resistance, excellent in weldability and part formability, It is possible to provide an anti-corrosive steel which is capable of suppressing galvanic corrosion occurring when it comes into contact with the exhaust gas, has a low corrosion rate, is excellent in corrosion resistance against exhaust gas condensed water of an internal combustion engine, and is excellent in economy and productivity.

In addition, the above-mentioned alloy components included in the above alloy composition are more likely to be thicker FeSO ₄ , FeSO ₄ and FeSO ₄ when they are exposed under complex corrosive environment including sulfuric acid, hydrochloric acid, nitric acid, SiO ₂ , and Cu-Sb composite coating layer can be formed, thereby reducing the dissolution rate of the material.

The antimony (Sb) and sulfur (S) function in a complex manner to form a dense coating of corrosion resistant steel, thereby preventing corrosion at the anode and acting as a catalyst poisoning. The consumption rate can be further reduced. In this case, resistance to sulfuric acid as well as corrosion resistance to a wider range of acidic environments including nitric acid and hydrochloric acid are better.

Concretely, among the alloy components, copper (Cu) may have a melting point of 1070 캜 to 1100 캜, for example, 1085 캜. Specifically, antimony (Sb) in the alloy component may have a melting point of 615 캜 to 645 캜, for example, 630 캜. Specifically, among the alloy components, iron (Fe) may have a melting point of 1518 캜 to 1553 캜, for example, 1538 캜. In this case, the corrosion resistant steel of the present invention can further improve the surface quality in the manufacturing process following continuous casting, hot rolling and cold rolling, and at the same time, it can realize more excellent corrosion resistance, moldability and high quality appearance.

Specifically, the alloy composition may include silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), niobium (Nb), copper (Cu), nickel (Ni), antimony (Sb) ) May be in the range of 0.2 wt% to 3.0 wt%. In this case, the economical efficiency and productivity can be further improved while realizing mechanical properties and corrosion resistance similar to those of stainless steel containing 11% or more of conventional chromium (Cr).

The total content of the antimony (Sb) and tin (Sn) may be 0.005 wt% to 0.2 wt%. Within the above range, the efficiency of the anode control and the cathode control can be further improved while being balanced. In addition, when large atomic radius and low melting point components such as antimony (Sb) and tin (Sn) are added in the above range, permeation of oxygen can be suppressed by a blocking effect.

The weight ratio of copper (Cu): antimony (Sb) in the alloy composition may be 2 to 3.5: 0.5 to 1. Within this range, the corrosion rate can be further reduced.

Specifically, the corrosion resistant steel having the corrosion resistance of the condensed water may have a corrosion rate (CR) value of 60 mm / year or less.

Corrosion rate is a value which is influenced not only by the composition and physical properties of steel but also by the application environment and the shape of parts. The corrosion-resistant steel with corrosion resistance of the present invention can exhibit excellent corrosion resistance even in a condensed water environment having a sulfuric acid concentration of 65% or less containing a large amount of H ₂ O, HSO ₄ ^- , and SO ₃ ^2- ions, for example.

<Condensation Corrosion Resistant Corrosion resistant steel  Manufacturing method>

Another embodiment of the present invention is a method of hot rolling a slab comprising the above-described alloy composition; And cold-rolling the steel to a corrosion resistant steel having a corrosion resistance of condensed water.

Accordingly, it is an object of the present invention to provide an exhaust gas condensate water purification device capable of suppressing galvanic corrosion, which is excellent in sulfuric acid resistance, acid fastness and hydrochloric acid resistance, excellent in weldability and part formability, Corrosion resistance is low, corrosion rate is low, and corrosion resistance is excellent in economy and productivity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a corrosion resistant steel having corrosion resistance against condensation water of the present invention will be described with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the specification.

1 is a process flow diagram illustrating a method for manufacturing a corrosion resistant steel having corrosion resistance against condensation water according to an embodiment of the present invention. Referring to FIG. 1, the method for manufacturing a corrosion resistant steel having corrosion resistance according to the present invention includes a hot rolling step (S100) and a cold rolling step (S200).

Hot-rolled  In step S100,

FIG. 2 is a process flowchart showing the step of hot rolling (S100) in the manufacturing method for an automotive part according to the present invention. 2, the hot rolling step comprises reheating the slab at a temperature of 950 to 1,250 ° C (SRT), performing hot rolling (S120) at an FDT of 800 to 950 ° C, (S130) at 100 占 폚 to 740 占 폚.

When the SRT reheating temperature is lower than 950 占 폚, the alloy components such as copper (Cu) are not sufficiently dissolved, which makes it difficult to secure the corrosion resistance, and the reheating temperature may be low and the rolling load may become large. Conversely, when the SRT exceeds 1,250 占 폚, the mechanical properties of the steel may be deteriorated with excessive energy consumption.

In the hot rolling (S120), the reheated steel slab is subjected to finish hot rolling under the conditions of FRT (Finishing Rolling Temperature): 800 ° C to 950 ° C. This finishing rolling temperature is a temperature at which the antimony (Sb) reacts with copper (Cu) and nickel (Ni) at a temperature set by having the melting point temperature before the hot rolling of the reheated steel slab to have a melting point temperature of 1100 캜 or more. . As a result, the rolling load at the time of rough rolling can be reduced by increasing the melting point temperature before hot rolling, and surface cracking can be prevented.

If the final hot rolling temperature is less than 800 ° C, there may occur problems such as generation of blisters due to abnormal reverse rolling. On the other hand, when the finish hot rolling temperature exceeds 950 占 폚, the austenite grains are coarsened and the ferrite grains are not sufficiently refined after the transformation, which may make it difficult to secure the strength.

After finishing rolling, the steel sheet can be cooled (S130) by cooling. When the coiling temperature exceeds 740 DEG C, it is difficult to control the degree of oxidation at the surface layer portion. On the other hand, if it is less than 100 캜, surface defects tend to occur.

After the hot rolling, the microstructure may include ferrite.

Cold-rolled  In step S200,

FIG. 3 is a process flowchart showing the cold rolling step (S200) in more detail in the manufacturing method for an automotive part according to the present invention. Referring to FIG. 3, the cold rolling step S200 includes a step of pickling (S210) the hot-rolled corrosion resistant steel with hydrochloric acid having a concentration of 17% to 90% at a temperature of 75 ° C to 85 ° C, (S220), followed by annealing (S230) at a temperature of 600 占 폚 to 860 占 폚.

The pickling treatment (S210) may be performed to remove the scale of the hot-rolled steel sheet before cold rolling. The pickling treatment with hydrochloric acid having a concentration of 17% to 90% at 75 to 85 캜 is advantageous in controlling the thickness of the oxide coating layer while being excellent in scale removal efficiency.

Thereafter, the pickled hot-rolled steel sheet is cold rolled (S220) and processed to the final thickness of the steel sheet. The reduction rate of the cold rolling can be set to about 50 to 70% depending on the thickness of the hot-rolled steel sheet and the final thickness of the steel sheet to be targeted.

The annealing heat treatment (S230) may be performed for about 30 seconds to 150 seconds by heating to 600 to 860 占 폚. Through the annealing, the austenite phase fraction can be controlled, thereby achieving the desired strength.

< Example >

Hereinafter, the structure and operation of the present invention will be described in more detail with reference to specific examples of the present invention. It should be understood, however, that the present invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Preparation of specimens

The slabs containing the alloy compositions shown in Table 1 were subjected to hot rolling and cold rolling under the conditions shown in Table 2 below to prepare specimens.

(weight%) C Si Mn P S Nb Cu Cr Ni Sb + Sn Ti Example 1 0.07 0.03 0.1 0.18 0.006 0.005 0.2 - 0.10 0.010 - Comparative Example 1 0.006 0.62 0.39 0.02 0.002 - - 11.28 0.12 - 0.2 Comparative Example 2 0.007 0.13 0.16 0.31 0.002 - - 17.63 0.20 - 0.34

fair
Hot rolling Pickling treatment Cold rolling SRT
(° C) FDT
(° C) Cooling rate
(° C / s) CT
(° C) group thickness Concentration of hydrochloric acid (%) Temperature
(° C) Reduction rate (%) Annealing temperature (캜) Heat treatment method Example 1 950 800 Shear cooling 100 FP 3 to 4 mm 17 75 ~ 85 ℃ 55 600 BAF Comparative Example 1 1250 800 Shear cooling 800 FP 3 to 4 mm 17 75 ~ 85 ℃ 55 500 BAF Comparative Example 2 1250 950 Shear cooling 850 FP 3 to 4 mm 17 75 ~ 85 ℃ 55 900 CAL

2. Property evaluation

Tables 3 and 4 show the results of evaluation of mechanical properties and corrosion resistance for the specimens according to Example 1 and Comparative Examples 1 and 2.

1) Mechanical properties: Tensile strength, yield strength and elongation were measured for the specimens according to Example 1 and Comparative Examples 1 and 2.

2) Corrosion: The specimens according to Example 1 and Comparative Examples 1 and 2 were cut to a size of 60 mm (width) * 25 mm (length) * 5 mm (thickness) by plasma cutting and then immersed in an immersion solution 10 wt% H ₂ SO ₄ and trace amounts of organic acid) in a filled beaker for 2 hours and then washed with distilled water. After the immersion, the corrosion state of the specimen was visually confirmed.

TS (MPa) YS (MPa) Elongation (%) Corrosion resistance Formability Example 1 360 260 40 Excellent (not lost) Great Comparative Example 1 290 189 27 Bad (loss) Wrinkle Comparative Example 2 330 195 19 Bad (loss) Cracking

The results of the corrosion test for the specimens of Example 1 and Comparative Examples 1 and 2 are shown in FIG. 4, (A1), (A2), and (B2) show the results obtained before and after immersion of the specimen of Example 1, (C1) shows the state before immersion of the specimen of Comparative Example 2, and (C2) shows the state after immersion of the specimen of Comparative Example 2, respectively.

As can be seen from FIG. 4, the specimen of Example 1 of the present invention had excellent corrosion resistance and was not corroded by the immersion liquid. On the other hand, in the specimens of Comparative Example 1 and Comparative Example 2, the portions where the immersion liquid and the specimen contacted with each other were lost by corrosion.

3) Change of immersion liquid: The specimens according to Example 1 and Comparative Example 1 were cut by plasma cutting to a size of 60 mm (width) * 25 mm (length) * 5 mm (thickness) (10 wt% H ₂ SO ₄ and trace amount of organic acid), and then the change of the immersion liquid was visually observed before the immersion, 30 minutes after immersion, and 120 minutes after immersion. The results of the change of the immersion liquid are shown in Table 4 and FIG.

Immediately after immersion Immersion for 30 minutes Immersion 120 minutes elapsed Example 1 Hydrogen generation Hydrogen generation Trace of hydrogen generation Comparative Example 1 Hydrogen spike generation Hydrogen spike generation Destruction of specimen by complete erosion

5, the immersion liquid immediately after the specimen of Example 1 was immersed in (A0), the immersion liquid after 30 minutes of immersion was (A30), and the immersion liquid after 120 minutes of immersion was (A120) The immersion liquid immediately after immersion was (B0), the immersion liquid after (B30) immersion for 30 minutes, and the immersion liquid after (120 minutes after immersion) was (B120).

4) Corrosion rate: The specimens according to Example 1 and Comparative Example 1 were dipped in 3500 cc of an artificial condensate at 50 ° C for 2 hours, left to stand for 22 hours, 1500cc of the artificial condensed water was drained, 1500 cc of condensate was newly added to measure the corrosion rate at the point of 1 day and 2 days. The results are shown in Table 5 below.

1 day elapsed time of artificial condensate test Two days after the artificial condensate test Example 1 0.8 0.05 Comparative Example 1 3.9 3.4

(Unit: 10 ^-3 mm / hr)

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Such changes and modifications are intended to fall within the scope of the present invention unless they depart from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

Claims (8)

(P): more than 0 to 0.18% by weight; (P): 0.001 to 0.10% by weight of carbon; 0.01 to 0.50% by weight of silicon; 0.05 to 0.15% 0.001 wt% to 0.01 wt% of copper, 0.10 wt% to 0.30 wt% of nickel, and 0.001 wt% to 0.5 wt% of nickel (Ni) 0.005 to 0.12 wt.% Of antimony (Sb), 0.005 wt.% To 0.12 wt.% Of tin (Sn) and an alloy composition of the balance iron (Fe) and other unavoidable impurities,
Corrosion resistant corrosion resistant steel having a tensile strength (TS) of 340 MPa to 450 MPa, a yield strength (YS) of 200 MPa to 350 MPa and an elongation of 30% to 45%.
The method according to claim 1,
The content of silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), niobium (Nb), copper (Cu), nickel (Ni), antimony (Sb) and tin The total amount is 0.2% by weight to 3.0% by weight,
Wherein the total content of antimony (Sb) and tin (Sn) is from 0.005% to 0.20% by weight of corrosion resistant steel.
The method according to claim 1,
Wherein said corrosion resistant steel is a corrosion resistant steel having a corrosion resistance CR of less than or equal to 60 mm / year.
The method according to claim 1,
Wherein the weight ratio of copper (Cu) to antimony (Sb) in the alloy composition is from 2 to 3.5: 0.5 to 1.
(P): more than 0 to 0.18% by weight; (P): 0.001 to 0.10% by weight of carbon; 0.01 to 0.50% by weight of silicon; 0.05 to 0.15% 0.001 wt% to 0.01 wt% of copper, 0.10 wt% to 0.30 wt% of nickel, and 0.001 wt% to 0.5 wt% of nickel (Ni) Hot rolling a slab of an alloy composition comprising at least one of iron (Fe), antimony (Sb) at 0.005 wt% to 0.12 wt%, tin (Sn) at 0.005 wt% to 0.12 wt%, and balance of iron (Fe) and other unavoidable impurities ; And cold rolling,
Wherein the hot rolling comprises: heating the slab at a temperature between 950 DEG C and 1,250 DEG C for SRT, finishing rolling at 800 DEG C to 950 DEG C, shearing at a temperature of CT: 100 DEG C to 740 DEG C, A method of manufacturing a corrosion resistant steel having corrosion resistance.
6. The method of claim 5,
The cold rolling step comprises pickling the hot-rolled steel at 75 to 85 ° C with hydrochloric acid having a concentration of 17% to 90%, subjecting the hot-rolled steel to cold rolling at a reduction ratio of 50% to 80% A method for manufacturing a corrosion resistant steel having a corrosion resistance of condensed water including annealing heat treatment.
6. The method of claim 5,
Wherein the corrosion resistant steel has a corrosion resistance CR of 60 mm / year or less.
6. The method of claim 5,
Wherein the corrosion resistant steel has a tensile strength (TS) of 340 MPa to 450 MPa, a yield strength (YS) of 200 MPa to 350 MPa, and an elongation percentage of 30% to 45%.

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