KR101351947B1 - High heat-resistance cold-rolled steel sheet having excellent formability, corrosion resistance, surface properties for working and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a high heat-resistant cold-rolled steel sheet and a method for manufacturing the same excellent in workability, discoloration resistance and corrosion resistance, by weight: C: 0.01 to 0.10%, Mn: 0.10 to 0.35%, P: 0.003 to 0.020%, Al : 0.02 ~ 0.08%, Sn: 0.05 ~ 0.25%, Cu: 0.1 ~ 0.4%, N: 0.002 ~ 0.006%, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, balance Fe and other unavoidable impurities The high heat resistant cold rolled steel for processing and its manufacturing method which are excellent in workability, discoloration resistance, and corrosion resistance are made into a technical summary.
According to the present invention, it can be manufactured at low cost compared to the existing stainless steel sheet, has various processing characteristics of elongation flangeability, bending property and deep drawing (excellent room temperature workability), and age-resistant by solid element precipitation This increases the yield point, which does not cause the yield point not only excellent moldability, but also excellent high temperature strength, prolongs the life of the facility by securing the shape freezing properties of high-temperature applications, excellent discoloration resistance at high temperatures, Cu on the surface of the steel sheet By forming a system sulfide, it is possible to manufacture a high heat resistant cold rolled steel sheet having excellent corrosion resistance.

Description

HIGH HEAT-RESISTANCE COLD-ROLLED STEEL SHEET HAVING EXCELLENT FORMABILITY, CORROSION RESISTANCE, SURFACE PROPERTIES FOR WORKING AND MANUFACTURING METHOD THEREOF

The present invention relates to a high heat resistant cold rolled steel sheet and a method of manufacturing the same for use in automobiles, home appliances, boilers, and the like, and more particularly, high heat resistant cold rolled steel for excellent processing resistance and discoloration and corrosion resistance produced by optimizing steel components and process conditions. It relates to a steel sheet and a method of manufacturing the same.

In the past, cast iron was generally used in parts of products such as automobile exhaust systems, household flues, ovens, boilers, etc. An aluminum hot-dip galvanized steel sheet, a stainless steel sheet, etc. were processed and used.

Here, the high temperature characteristic is one of the characteristics when the processed product is used in a high temperature environment, such as sag resistance, high temperature strength and discoloration resistance, and the product characteristics may be deteriorated by local temperature rise when using a product such as an automobile exhaust system. Therefore, high temperature characteristics are required. The sag resistance is a phenomenon in which the steel sheet is repeatedly exposed to high temperature, causing a change in material and sagging. When such a phenomenon occurs, it is difficult to maintain the shape of the molded part, and when the thermal stress is concentrated to a specific place, Since the product shape is deformed or destroyed due to deterioration, it is necessary to satisfy the yield strength of 55 MPa or more at a high temperature of about 700 ° C. in order to secure the shape freezing property. Discoloration resistance, which is a surface property for securing, is required.

In addition, due to the characteristics of repeated high and low temperatures, there is a problem that rust occurs in the outside air and exposed metal parts, and in some cases, a hole is generated, causing corrosion. Therefore, higher corrosion resistance is required to prevent such corrosion. do.

Conventionally, stainless steel sheet has been mainly used for heat-resistance, but stainless steel sheet is not only expensive to manufacture due to the addition of expensive alloy elements such as Cr and Ni, but also the grain of Cr is combined with C when heated at high temperatures. There is a problem in that corrosion resistance is inferior due to grain boundary corrosion in the Cr depleted zone formed by chromium carbide precipitation.

In addition, in order to secure oxidation resistance at high temperatures, an aluminum hot dip galvanized steel sheet may be used. However, when the aluminum hot dip galvanized steel sheet is heated to a high temperature of 400 ° C. or higher, an alloy layer of an interface is grown due to the interdiffusion reaction between Fe and Al. There is a problem in that the application can be applied because it loses the gloss of the surface in a short time and the color change is insufficient heat resistance.

In addition, the heat-resistant steel sheet is manufactured to accommodate products in a limited space in addition to the above-described high temperature characteristics, such as automobile exhaust system, home communication, oven and boiler, and formed into a complicated shape by various methods to expand or bend after pipework. Because the process is required, room temperature processability is required.

In order to solve this problem, Japanese Patent Laid-Open No. Hei 8-319548 intends to manufacture a hot-dip aluminum plated steel sheet having excellent high temperature strength by forming a coating layer on the surface of the steel sheet, but improving the plating conditions rather than improving the characteristics of the steel sheet. Since the present invention is not only difficult to adjust when the plating layer is changed, there is a problem that it is difficult to obtain target heat resistance.

In addition, Japanese Laid-Open Patent Publication No. 9-176816 attempts to improve heat resistance and workability by heat-treating a steel sheet after adjusting aluminum content of Al and solid solution N in steel, but the steel sheet is used at a temperature of 550 ° C. or higher. It is difficult to apply it to a member of, and it is not easy to adjust the amount of the steel component to be added.

In addition, U.S. Patent No. 4,675,214 discloses that chromium, silicon, and manganese oxides are reduced on the surface of a stainless steel sheet having corrosion resistance or oxidation resistance under reducing gas atmosphere to clean the surface layer of the steel sheet, and then immersed in a molten aluminum bath to produce plating. Although aluminum plated stainless steel is proposed, a separate facility for reduction is required and the working conditions are complicated, and the formation of an aluminum-iron-based alloy layer is prevented due to the formation of CrN on the surface of the steel sheet, causing a plating failure, and Peeling of an alloy layer tends to occur, and there exists a problem which is difficult to obtain target heat resistance and corrosion resistance.

In order to solve the above problems, the present inventors have repeatedly conducted research and experiments and propose the present invention based on the results, and the present invention has high temperature characteristics and room temperature processability, such as automobile exhaust system, home communication, oven and boiler. At the same time, high heat-resistant cold-rolled steel sheet and its manufacture, which can be manufactured at low cost by optimizing steel components and processing conditions while reducing the addition of low-cost carbon and adding expensive alloying elements, for use in demanding applications. The purpose is to provide a method.

In the present invention, C: 0.01 to 0.10%, Mn: 0.10 to 0.35%, P: 0.003 to 0.020%, Al: 0.02 to 0.08%, Sn: 0.05 to 0.25%, Cu: 0.1 to 0.4%, and N: Provides a high heat resistant cold rolled steel sheet having excellent discoloration resistance and corrosion resistance including 0.002 to 0.006%, Ti: 0.07 to 0.15%, S: 0.003 to 0.010%, balance Fe and other unavoidable impurities.

At this time, the characteristic of the atomic ratio Ti / C of Ti and C is 0.3 to 0.8.

In addition, the cold rolled steel sheet is also characterized in that the Ti-based carbide precipitates are formed.

In addition, the characteristic is that the value of the atomic ratio Cu / S of said Cu and S is 10-25.

In addition, the Cu-based sulfide is formed on the surface of the cold-rolled steel sheet has its characteristics.

Here, the Cu-based sulfide is characterized by being Cu ₂ S.

In addition, the cold rolled steel sheet is characterized in that it is made of an equiaxed ferrite and acicular ferrite structure.

At this time, the volume fraction of the needle-like ferrite structure is also characterized in that 5 to 10%.

In addition, the Sn-based oxide layer formed on the surface of the cold-rolled steel sheet is also characterized.

Here, the Sn-based oxide layer is also characterized by being a Sn ₂ O ₃ layer.

In addition, the present invention is in the weight% C: 0.01 to 0.10%, Mn: 0.10 to 0.35%, P: 0.003 to 0.020%, Al: 0.02 to 0.08%, Sn: 0.05 to 0.25%, Cu: 0.1 to 0.4%, Steel slab containing N: 0.002 ~ 0.006%, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, balance Fe and other unavoidable impurities is heated, hot rolled, cold rolled, and then cold rolled Annealing the steel sheet at a temperature of 750 ℃ or more, and provides a method for producing a high temperature resistant cold rolled steel sheet for processing excellent in color resistance and corrosion resistance characterized in that cooling to the cooling rate of 30 ℃ / sec or more with respect to the annealing steel sheet.

In this case, the steel slab is characterized in that the value of the atomic ratio Ti / C of the Ti and C is 0.3 ~ 0.8.

In addition, the steel slab is characterized by having an atomic ratio Cu / S of Cu to S of 10 to 25.

In addition, the hot rolling is characterized in that it comprises the step of finishing rolling at 880 ~ 950 ℃.

Further, there is also a feature that further comprises the step of cooling the hot rolled hot rolled sheet in the finishing rolling step at a cooling rate of 20 ~ 80 ℃ / sec.

Moreover, the said winding has the characteristic also when it is performed at 560-680 degreeC.

The annealing treatment is also characterized by being performed at 750 to 900 ° C.

According to the present invention, it can be manufactured at low cost compared to the existing stainless steel sheet, and has various processing characteristics of elongation flangeability, bending property and deep drawing property, which is excellent at room temperature workability, and yield resistance is increased due to the increase in the aging resistance by precipitation of solid elements. Not only does the phenomenon occur, it is not only excellent in formability, but also excellent in high temperature strength, ensuring the shape freezing property of high-temperature applications, extending the life of the equipment, and excellent discoloration resistance at high temperatures. It is possible to manufacture a high heat resistant cold rolled steel sheet for processing having excellent corrosion resistance.

Hereinafter, the cold-rolled steel sheet of the present invention will be described in detail.

The inventors have satisfied various processing characteristics such as stretch-flangeability, bendability, deep drawing and other anti-aging properties at a low cost, and at least 55 MPa at 700 ° C. The present invention has been completed by repeated studies and experiments to secure yield strength and discoloration resistance and corrosion resistance at high temperatures. As a result, the present invention contains a low to medium carbon content and controls the addition amount of Ti and the atomic ratio of Ti and C in the steel component to form fine Ti-based carbide precipitates, and by optimizing the annealing and cooling conditions, the volume fraction of acicular ferrite structure Sn is added to form a Sn-based oxide layer on the surface of the steel sheet, and by controlling the amount of Cu and the atomic ratio of Cu and S to form a Cu-based sulfide on the surface of the steel sheet, heat resistance, corrosion resistance and discoloration resistance and room temperature at high temperature It has the characteristics to manufacture high heat resistant cold rolled steel sheet suitable for product parts such as automobile exhaust system, home communication, oven and boiler, because of its excellent aging resistance and workability.

First, the reasons for limiting components of the present invention will be described.

Carbon (C) is an element added to improve the strength of a steel sheet, and is mainly consumed in the present invention by reaction with Ti for Ti-based carbide formation. As the amount of C added increases, the tensile and yield strength increases, but when added excessively, the workability decreases, so the upper limit is preferably 0.1%. If less than 0.01%, however, sufficient Ti-based carbide precipitates may not be strengthened, and grain size may increase, causing a sharp change in material, so that the C content is limited to 0.01 to 0.1%.

Manganese (Mn) is a solid solution strengthening element, which improves the strength of steel and improves hot workability, but inhibits ductility and workability by MnS formation. Therefore, when Mn is added in excess, the ductility is lowered and the economical efficiency due to the addition of a large amount of alloying elements becomes a cause of generation of center segregation, so that the upper limit is preferably 0.35%. However, if less than 0.10%, the workability is improved, but it is difficult to secure the target high strength, Mn content is limited to 0.10 ~ 0.35%.

Aluminum (Al) is an element added for deoxidation of molten steel and is preferably contained in an amount of 0.02% or more because it is combined with solid solution elements in steel to improve aging characteristics. However, excessive addition of more than 0.08% increases the amount of inclusions in the steel, causing surface defects and lowering the workability, Al content is limited to 0.02 ~ 0.08%.

Phosphorus (P) is an important element that improves the strength and corrosion resistance of steel, and it is preferable to contain 0.003% or more in order to secure these properties. However, if the content exceeds 0.020%, it causes central segregation during casting and lowers workability. The content of is limited to 0.003 ~ 0.020%.

Nitrogen (N) is a solid element inside the steel and is effective for reinforcing the material. If it is contained less than 0.002%, sufficient rigidity cannot be obtained and the precipitate formation site is reduced. As a cause of aging and hardening occurs to deteriorate moldability, the content of N is limited to 0.002 ~ 0.006%.

Sulfur (S) combines with Mn and Cu in the steel to form non-metallic inclusions that serve as a starting point for corrosion and causes red shortness, so it is desirable to reduce the content as much as possible, so the content of S should be less than 0.010%. It is limited. However, in order to form a Cu-based sulfide such as Cu ₂ S on the surface of the steel sheet to ensure high corrosion resistance, a content of 0.003% or more is required, so the content of S is limited to 0.003 to 0.010%.

Titanium (Ti) is an effective element for increasing the strength of steel sheet and refining grains, and in the present invention, Ti-based carbide precipitates are combined with solid solution C in steel to improve aging and formability. It is preferably contained at least 0.07% because the strength is increased and the grain growth at a high temperature is suppressed to provide the effect of refining the ferrite particles, but when the content exceeds 0.15%, the material is cured and the operability of the continuous annealing treatment is decreased. Deteriorates the surface properties of the steel sheet, the content of Ti is limited to 0.07 ~ 0.15%.

Tin (Sn) is an element that exists in a solid state inside the steel to improve high temperature characteristics and corrosion resistance, and is heated and oxidized by heat treatment to form Sn-based oxides such as Sn ₂ O ₃ on the surface of the steel sheet, thereby forming an alloying layer on the surface of the steel sheet. It is preferable to add 0.05% or more in order to obtain such effects, but if the content exceeds 0.25%, it is a factor of increase in manufacturing cost rather than contributing to improvement of corrosion resistance or discoloration resistance. Therefore, the content of Sn is limited to 0.05 ~ 0.25%.

In the case of Ti and Cu, it is also important to manage alone, but in order to secure the high temperature and room temperature characteristics targeted by the present invention, it is necessary to consider the effects of precipitate formation and solid solution elements in the steel. To this end, the atomic ratio Ti / C of Ti and C and the atomic ratio Cu / S of Cu and S must be maintained in a certain range to ensure room temperature aging resistance, processability, high temperature characteristics, and corrosion resistance at the same time.

Here, when the value of Ti / C, which is the atomic ratio of Ti and C, is 0.3 to 0.8, solid carbide element C is fixed in the steel by the formation of Ti-based carbide precipitates, thereby ensuring room temperature resistance and workability, and annealing and cooling conditions. By appropriately controlling the growth of fine Ti-based carbide precipitates by suppressing grain growth at high temperatures to control the ferrite microstructure can ensure excellent high-temperature characteristics.

However, when the value of Ti / C, which is an atomic ratio of Ti and C, is less than 0.3, there is a problem that the room temperature aging resistance and workability may be deteriorated due to excessive solid solution elements in the steel, and because the amount of Ti-based carbide precipitates is insignificant, high temperature is excellent. Strength may be difficult to secure. On the other hand, if the value exceeds 0.8, the material may be cured, the temperature of the recrystallization may be increased rapidly, and the surface properties may be degraded, thereby degrading workability of the post process. It is preferable to limit the value of Ti / C to 0.3-0.8.

In addition, when the value of Cu / S, which is an atomic ratio of Cu and S, is less than 10, the formation of Cu-based sulfides that contribute to the improvement of corrosion resistance may be insufficient, and the effect of improving corrosion resistance may be reduced. When the value of Cu / S exceeds 25, The occurrence frequency of surface defects due to the solid solution of Cu in steel may increase, and the value of Cu / S is preferably limited to 10-25.

The cold rolled steel sheet of the present invention comprises the above components and consists of the remainder Fe and other unavoidable impurities. And alloy elements may be further added as needed to improve the properties of the present cold-rolled steel sheet, alloy elements that are not identified in the embodiment of the present invention is not interpreted to be excluded from the scope of the present invention.

On the other hand, the cold-rolled steel sheet of the present invention is characterized by consisting of an equiaxed ferrite (polygonal ferrite) and acicular ferrite (acicular ferrite) tissue, the needle-like ferrite tissue is a kind of bainite grown by nucleation in the mouth of austenite before transformation As the nucleation grows from the fine non-metallic inclusions dispersed in the steel, the ferrite laths are relatively superior in ductility or toughness due to the disordered structure in which the ferrite laths form a high angle boundary with each other.

The present invention secures the volume fraction of the needle-like ferrite structure by 5-10% by appropriately controlling the conditions of the annealing and cooling process to form a high-potential-density type microstructure, thereby suppressing abnormal growth of grains at high temperature, thereby increasing the high temperature strength. It is possible to further improve heat resistance. When the volume fraction of the acicular ferrite structure is less than 5%, it may be difficult to secure very good high temperature strength, so that it may be difficult to obtain target heat resistance, and when the volume fraction of the acicular ferrite structure exceeds 10%, the material is hardened. There is a problem that the workability may deteriorate, and the volume fraction of the needle-like ferrite is limited to 5 to 10%.

Hereinafter, the manufacturing method of the high heat resistant cold rolled steel sheet for processing excellent in workability, heat resistance, and discoloration resistance of this invention is demonstrated in detail.

After reheating the steel slab having the above composition, it is hot rolled, cold rolled after winding, and cooled at a cooling rate of 30 ° C./sec or higher on an annealing steel sheet at a temperature of 750 ° C. or higher to provide excellent workability, heat resistance, and discoloration resistance. High heat resistant cold rolled steel sheet for processing can be produced.

After reheating the steel slab formed as the above-described component system at a normal temperature, the finish rolling temperature during hot rolling is preferably in the range of 880 to 950 ° C. If the finish rolling temperature is less than 880 ° C., hot rolling is performed at a relatively low temperature region. As this is terminated, the final formed grains may be mixed, resulting in deterioration of workability and rolling property, and when the finish rolling temperature exceeds 950 ° C., uniform hot rolling may not be performed throughout the thickness, resulting in insufficient grain refinement. In this case, the impact toughness may be lowered due to grain coarsening, so the finish rolling temperature is preferably limited to 880 to 950 ° C.

After the hot finish rolling, it is preferable to cool the hot rolled steel sheet in a run-out table at a cooling rate of 20 to 80 ° C./sec. If the cooling rate is less than 20 ° C./sec, it is necessary to promote grain growth. This is because coarse crystal grains are formed, which may be a cause of deterioration in strength and workability. When the cooling rate exceeds 80 ° C / sec, there is a possibility of acting as a cause of variation of materials due to the uneven cooling in the width direction.

After cooling in the runout table, the hot rolled steel sheet is preferably wound at a temperature of 560 ~ 680 ℃. At this time, when the coiling temperature is less than 560 ℃, the material of the hot rolled material is somewhat hardened and the load in the cold rolling process, which is the next process, becomes large, and thus it is difficult to secure the rolling property, and the non-uniformity of the widthwise temperature is increased, resulting in low temperature precipitates. Due to the difference in the production behavior of the material deviation may be caused, the workability may be reduced, there is a problem that the high temperature characteristics may also be deteriorated. In addition, when the coiling temperature exceeds 680 ° C, the structure of the final product may be coarse, and there is a problem that the workability and corrosion resistance may be lowered. Therefore, the coiling temperature is preferably limited to 560 to 680 ° C.

After the wound steel sheet is subjected to a pickling process and cold rolling to a target thickness, it is preferable to undergo a continuous annealing process at a temperature of 750 ° C. or higher for recrystallization and microstructure control. The annealing temperature of 750 ℃ or more corresponds to a temperature for sufficiently securing the transformation driving force of the needle-like ferrite structure. Here, when the annealing temperature is less than 750 ℃, it is difficult to obtain the volume fraction of the needle-like ferrite structure present in the microstructure of the target steel sheet, and thus there is a problem that it is difficult to secure very good room temperature and high temperature strength. However, since the surface defects of the steel sheet may increase during high temperature annealing, the annealing temperature is preferably managed at 900 ° C. or lower.

The annealed steel sheet can secure a volume fraction of the target acicular ferrite structure through a cooling process, for which the cooling rate is maintained at 30 ℃ / sec or more. If the cooling rate is less than 30 ° C / sec, it is difficult to obtain the volume fraction of the target needle-like ferrite due to slow cooling.

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

[Example]

Invented steels 1 and 2 and Comparative steels 1 to 5 prepared by melting the composition shown in Table 1 below under the process conditions as shown in Table 2 to produce cold rolled steel invention materials 1 to 5 and comparative materials 1 to 10 After that, the volume fraction of the acicular ferrite structure and the characteristics at room temperature and high temperature were evaluated for each of the prepared cold rolled steel sheets.

Yield elongation phenomenon of the characteristics shown in Table 3 was measured when the yield point elongation was measured and occurred when the elongation occurred, and not occurred when the elongation did not occur, and the bending resistance test was the surface bending after the steel sheet processing. According to the degree of occurrence, the bending index representing this was divided into 5 stages, and 1 to 2 stages with relatively small bending were good, and 3 to 5 stages where the bending occurred to the extent that visual observation can be judged as bad. .

In addition, the sag resistance test was determined to be defective when the sagging of the steel sheet after measuring the sagging of the steel plate after heating the material of 250mm in length, 30mm in width for 100 hours at 700 ℃ using a heat treatment equipment, The high temperature yield strength test was judged to be bad if the yield strength was less than 55MPa at 700 ° C, and higher than that. The high temperature discoloration resistance test showed that the surface glossiness was lowered by more than 30% after maintaining the steel plate at 500 ° C for 48 hours. It was judged to be defective.

In addition, the corrosion resistance test was determined that the corrosion loss after the salt spray experiment with 5% NaCl for 480 hours is less than 0.05g / cm ² , if it is higher than that, the workability test is a crack that occurs during normal temperature processing It was judged as bad in the case.

At this time, in Table 1, the value of the atomic ratio Ti / C of Ti and C and the value of the atomic ratio Cu / S of Cu and S refer to the ratio of the value obtained by dividing the weight percent of each element by its atomic weight.

Table 1 Components of Inventive and Comparative Steels

[Table 2] Condition of Manufacturing Process by Steel Plate

[Table 3] Evaluation of properties by steel plate

As shown in Table 3, Inventive Materials 1 to 5 in which the steel component and the process conditions satisfy the scope of the present invention had no yield point stretching phenomenon and good bending resistance, which was excellent in aging resistance, and Ti-based carbide precipitates. The yield strength at high temperatures and the sag resistance after heat treatment (sag resistance) were good due to the formation of and the optimization of the volume fraction of the needle-like ferrite structure, and the Sn-based oxide layer was formed on the surface of the steel sheet to reduce the surface glossiness at 30%. The discoloration resistance was good to less than, Cu-based sulfide was formed on the surface of the steel sheet, and the corrosion resistance was also good.

On the other hand, although the steel components of Table 1 and the like are the invention steels satisfying the scope of the present invention, Comparative Materials 1 to 5, in which some of the process conditions of Table 2 are outside the scope of the present invention, are mostly low in volume fraction of acicular ferrite structure. It did not have high temperature characteristics, and workability and aging resistance, including corrosion resistance, were also often worse than Inventions 1 to 5.

In addition, although the process conditions of Table 2 satisfy the scope of the present invention, Comparative Materials 6 to 10 in which the steel component and the atomic ratio of Table 1 are out of the range of the present invention are low in volume fraction of acicular ferrite structure, and have high temperature and high temperature characteristics. There were many bad cases.

Among them, comparative material 8 had no yield point stretching phenomenon and good bending resistance and workability, but poor sag resistance, high temperature yield strength and high temperature discoloration resistance and corrosion resistance corresponding to high temperature characteristics. This is because not only the workability deteriorated, the properties of the steel sheet surface were deteriorated, and Cu-based sulfides were not formed by addition of Cu, so that the target corrosion resistance could not be secured. In addition, Comparative Materials 6, 7, 9, and 10 were not only poor in workability and aging resistance, but also had a low Ti / C value, which resulted in a small amount of Ti-based carbide precipitates and a low volume fraction of acicular ferrite structure. In particular, the comparative material 9 had a high Cu / S value, and thus the frequency of occurrence of surface defects was increased by solid solution solid solution Cu. Comparative materials 6 and 10 had poor corrosion resistance because Cu-based sulfides were not formed without Cu addition.

Eventually, the compositional conditions of the steel and the conditions of the manufacturing process (particularly annealing and cooling conditions) can be optimized to form fine Ti-based carbide precipitates, the volume fraction of the acicular ferrite structure can be controlled, and Sn is added to the steel sheet surface. By forming a type oxide and forming Cu type sulfide by adding Cu, it was possible to manufacture a high heat resistant cold rolled steel sheet for processing that satisfies both discoloration resistance and corrosion resistance at low cost.

The above-described embodiments are illustrative examples of the present invention are not limited thereto. Anything having substantially the same constitution as the technical idea described in the claims of the present invention and achieving the same operational effect is included in the technical scope of the present invention.

Claims (17)

By weight% C: 0.01 ~ 0.10%, Mn: 0.10 ~ 0.35%, P: 0.003 ~ 0.020%, Al: 0.02 ~ 0.08%, Sn: 0.05 ~ 0.25%, Cu: 0.1 ~ 0.4%, N: 0.002 ~ 0.006 %, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, remainder Fe and other unavoidable impurities, high heat resistant cold rolled steel sheet for processing, excellent in discoloration resistance and corrosion resistance, Cu-based sulfides formed on the surface. The method of claim 1,
A high heat resistant cold rolled steel sheet having excellent discoloration resistance and corrosion resistance, wherein the atomic ratio Ti / C of Ti and C is 0.3 to 0.8. The method of claim 1,
The cold rolled steel sheet is a high heat resistant cold rolled steel sheet for processing excellent in color resistance and corrosion resistance characterized in that the Ti-based carbide precipitates are formed. The method of claim 1,
A high heat resistant cold rolled steel sheet for processing having excellent discoloration resistance and corrosion resistance, wherein the Cu and S have an atomic ratio Cu / S of 10 to 25. delete 5. The method according to any one of claims 1 to 4,
The Cu-based sulfide is Cu ₂ S high heat resistance cold rolled steel sheet excellent in discoloration resistance and corrosion resistance. By weight% C: 0.01 ~ 0.10%, Mn: 0.10 ~ 0.35%, P: 0.003 ~ 0.020%, Al: 0.02 ~ 0.08%, Sn: 0.05 ~ 0.25%, Cu: 0.1 ~ 0.4%, N: 0.002 ~ 0.006 %, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, remainder Fe and other unavoidable impurities, high heat resistant cold rolled steel for excellent discoloration and corrosion resistance, characterized by consisting of an isometric ferrite and acicular ferrite structure Grater. The method of claim 7, wherein
A high heat resistant cold rolled steel sheet for processing excellent in discoloration and corrosion resistance, characterized in that the volume fraction of the acicular ferrite structure is 5 ~ 10%. The method according to any one of claims 1 to 4 and 6 to 8,
A high heat resistant cold rolled steel sheet having excellent discoloration resistance and corrosion resistance, characterized in that a Sn-based oxide layer is formed on the surface of the cold rolled steel sheet. By weight% C: 0.01 ~ 0.10%, Mn: 0.10 ~ 0.35%, P: 0.003 ~ 0.020%, Al: 0.02 ~ 0.08%, Sn: 0.05 ~ 0.25%, Cu: 0.1 ~ 0.4%, N: 0.002 ~ 0.006 %, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, remainder Fe and other unavoidable impurities, high heat resistant cold rolled steel sheet for processing, excellent in discoloration and corrosion resistance, Sn ₂ O ₃ layer formed on the surface. By weight% C: 0.01 ~ 0.10%, Mn: 0.10 ~ 0.35%, P: 0.003 ~ 0.020%, Al: 0.02 ~ 0.08%, Sn: 0.05 ~ 0.25%, Cu: 0.1 ~ 0.4%, N: 0.002 ~ 0.006 Steel slab containing%, Ti: 0.07 ~ 0.15%, S: 0.003 ~ 0.010%, balance Fe and other unavoidable impurities is heated and hot rolled, cold rolled after winding, and then cold rolled steel sheet Annealing at a temperature, and then cooled to a cooling rate of 30 ℃ / sec or more with respect to the annealed steel sheet, Cu-based sulfide is formed on the surface of the cooled steel sheet, high heat resistance cold-rolled steel sheet for processing excellent in color resistance and corrosion resistance Manufacturing method. 12. The method of claim 11,
The steel slab is a method of manufacturing a high heat resistance cold rolled steel sheet having excellent discoloration resistance and corrosion resistance, characterized in that the value of the Ti / C atomic ratio Ti / C of 0.3 ~ 0.8. 12. The method of claim 11,
The steel slab is a method for producing a high heat resistance cold rolled steel sheet having excellent discoloration resistance and corrosion resistance, characterized in that the Cu / S atomic ratio of Cu / S value of 10 to 25. The method according to any one of claims 11 to 13,
The hot rolling is a manufacturing method of a high heat resistant cold rolled steel sheet for excellent color resistance and corrosion resistance comprising the step of finish rolling at 880 ~ 950 ℃. 15. The method of claim 14,
The method of manufacturing a high heat resistant cold rolled steel sheet having excellent discoloration resistance and corrosion resistance, further comprising the step of cooling the hot rolled hot rolled sheet in the finishing rolling step at a cooling rate of 20 to 80 ° C./sec. The method according to any one of claims 11 to 13,
The winding is carried out at 560 ~ 680 ℃ manufacturing method of high heat resistant cold rolled steel sheet excellent in discoloration resistance and corrosion resistance. The method according to any one of claims 11 to 13,
The annealing treatment is carried out at 750 ~ 900 ℃ a manufacturing method of a high heat-resistant cold-rolled steel sheet for processing excellent in discoloration and corrosion resistance.