KR20130088329A - Steel sheet and method of manufacturing the steel sheet - Google Patents
Steel sheet and method of manufacturing the steel sheet Download PDFInfo
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- KR20130088329A KR20130088329A KR1020120009496A KR20120009496A KR20130088329A KR 20130088329 A KR20130088329 A KR 20130088329A KR 1020120009496 A KR1020120009496 A KR 1020120009496A KR 20120009496 A KR20120009496 A KR 20120009496A KR 20130088329 A KR20130088329 A KR 20130088329A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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Abstract
Description
The present invention relates to a steel sheet and a method for manufacturing the same, and more specifically, chromium (Cr), nickel (Ni), copper (Cu), niobium (Nb) and vanadium (V) are added to have a tensile strength of 490 MPa or more. The present invention relates to a steel sheet having excellent weather resistance and a method of manufacturing the same.
When the steel sheet is used in bridges and the like, the scale of the surface is removed, and after the anti-corrosion coating, the steel is welded to install the structure. However, these operations can be repainted every few years, so maintenance costs can continue to increase.
Therefore, in recent years, the steel plate excellent in weatherability is needed.
Background art related to the present invention is the Republic of Korea Patent Publication No. 10-2000-0043769 (2000.07.15. Publication), the document discloses a hot rolled steel sheet excellent in workability and weather resistance and a method of manufacturing the same.
An object of the present invention is to provide a steel sheet manufacturing method that can improve weather resistance with high strength by adding chromium (Cr), nickel (Ni), copper (Cu), niobium (Nb) and vanadium (V).
Another object of the present invention is to provide a steel sheet manufactured by the above method, having a tensile strength (TS) of at least 490 MPa, a yield strength of at least 355 MPa, and a Charpy average impact absorption energy at 0 ° C. of at least 47 J.
Steel sheet manufacturing method according to an embodiment of the present invention for achieving the above object is carbon (C): 0.1 to 0.2% by weight, silicon (Si): 0.6% by weight or less, manganese (Mn): 0.5 to 1.8% by weight Phosphorus (P): 0.02 wt% or less, Sulfur (S): 0.01 wt% or less, Chromium (Cr): 0.4-1.0 wt%, Nickel (Ni): 0.2-1.0 wt%, Molybdenum (Mo): 0.2- 1.0 wt%, aluminum (Al): 0.03 wt% or less, copper (Cu): 0.2-1.0 wt%, titanium (Ti): 0.01-0.02 wt%, niobium (Nb): 0.005-0.05 wt%, vanadium (V) ): 0.055 ~ 0.10 wt%, Boron (B): 0.0001 ~ 0.0050 wt%, Nitrogen (N): 0.007 wt% or less, Tin (Sn): 0.0002 ~ 0.0015 wt%, Calcium (Ca): 0.000 4 wt% or less And reheating the slab plate made of the remaining iron (Fe) and unavoidable impurities. Hot rolling the reheated plate to a finishing rolling temperature of 850 ° C. to 1050 ° C .; And cooling the rolled sheet material.
Steel sheet according to an embodiment of the present invention for achieving the other object is carbon (C): 0.1 to 0.2% by weight, silicon (Si): 0.6% by weight or less, manganese (Mn): 0.5 to 1.8% by weight, phosphorus ( P): 0.02 wt% or less, Sulfur (S): 0.01 wt% or less, Chromium (Cr): 0.4 to 1.0 wt%, Nickel (Ni): 0.2 to 1.0 wt%, Molybdenum (Mo): 0.2 to 1.0 wt% , Aluminum (Al): 0.03% by weight or less, Copper (Cu): 0.2-1.0% by weight, titanium (Ti): 0.01-0.02% by weight, niobium (Nb): 0.005-0.05% by weight, vanadium (V): 0.055 ~ 0.10% by weight, boron (B): 0.0001 to 0.0050% by weight, nitrogen (N): 0.007% by weight or less, tin (Sn): 0.0002 to 0.0015% by weight, calcium (Ca): 0.000４% by weight or less (Fe) and inevitable impurities.
Steel sheet according to the present invention can improve the weather resistance through the alloy components of chromium (Cr), nickel (Ni), copper (Cu), niobium (Nb) and vanadium (V).
In addition, the steel sheet according to the present invention can satisfy the tensile strength (TS): 490MPa or more, yield strength: 355MPa or more and Charpy average impact absorption energy at 0 ° C: 47J or more.
1 is a flowchart showing a steel sheet manufacturing method according to an embodiment of the present invention.
2 and 3 is a graph showing the Charpy average impact absorption energy for each temperature of the specimen prepared according to Examples 1 to 2 of the present invention.
4 and 5 are graphs showing the corrosion resistance evaluation results for the specimens prepared according to Examples 1 and 2 and Comparative Examples 1 and 2.
Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.
Hereinafter, a steel sheet according to a preferred embodiment of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.
Steel plate
Steel sheet according to the present invention is carbon (C): 0.1 to 0.2% by weight, silicon (Si): 0.6% by weight or less, manganese (Mn): 0.5 to 1.8% by weight, phosphorus (P): less than 0.02% by weight, sulfur ( S): 0.01 wt% or less, Chromium (Cr): 0.4 to 1.0 wt%, Nickel (Ni): 0.2 to 1.0 wt%, Molybdenum (Mo): 0.2 to 1.0 wt%, Aluminum (Al): 0.03 wt% or less , Copper (Cu): 0.2 to 1.0% by weight, titanium (Ti): 0.01 to 0.02% by weight, niobium (Nb): 0.005 to 0.05% by weight, vanadium (V): 0.055 to 0.10% by weight, boron (B): 0.0001 to 0.0050% by weight, nitrogen (N): 0.007% by weight or less, tin (Sn): 0.0002 to 0.0015% by weight, calcium (Ca): 0.000 4% by weight and the remaining iron (Fe) and inevitable impurities.
At this time, the steel sheet according to the present invention may have a tensile strength (TS): 490 MPa or more, yield strength (YS): 355 MPa or more and elongation (EL): 1% or more.
Hereinafter, the role and content of each component included in the steel sheet according to the present invention will be described.
Carbon (C)
Carbon (C) is added to secure strength and is the most influential element in weldability. In this case, the influence of the alloying elements other than carbon (C) may be expressed as a carbon equivalent (carbon equivalent: CEQ) equivalently converted to carbon (C).
The carbon (C) is preferably added in a content ratio of 0.1 to 0.2% by weight of the total weight of the steel sheet. If the content of carbon (C) is less than 0.1% by weight, it may be difficult to secure sufficient strength. On the contrary, when the content of carbon (C) exceeds 0.2% by weight, it may cause a decrease in toughness, and there is a problem of lowering weldability during electric resistance welding (ERW).
silicon( Si )
In the present invention, silicon (Si) is added as a deoxidizer for removing oxygen in the steel in the steelmaking process. Silicon (Si) also has a solid solution strengthening effect.
However, when the content of silicon (Si) exceeds 0.6 wt% of the total weight of the steel sheet, the weldability of the steel is degraded, and the red scale is generated during reheating and hot rolling, which may cause a problem on the surface quality. have. Further, the plating ability after welding can be inhibited. Thus, in the present invention, the content of silicon (Si) was limited to 0.6 wt% or less of the total weight of the steel sheet.
manganese( Mn )
Manganese (Mn) is an element that is effective for enhancing hardenability of steel by strengthening solid solution strength.
The manganese (Mn) is preferably added in a content ratio of 0.5 to 1.8% by weight of the total weight of the steel sheet. If the content of manganese (Mn) is added less than 0.5% by weight may have a solid solution strengthening effect. On the contrary, when the content of manganese (Mn) is excessively added in excess of 1.8 wt%, not only the weldability is greatly reduced, but also the problem of greatly reducing the ductility of the steel sheet due to the generation of MnS inclusions and the occurrence of center segregation is caused. have.
Phosphorus (P)
Phosphorus (P) is an element contributing to strength improvement.
The phosphorus (P) may deteriorate the weldability and cause a final material deviation due to slab center segregation.
Thus, in the present invention, the content of phosphorus (P) was limited to 0.02% by weight or less of the total weight of the steel sheet.
Sulfur (S)
Sulfur (S) is an element that inhibits the toughness and weldability of steel and combines with manganese (Mn) to form MnS non-metallic inclusions to generate cracks during processing of steel. When the content of sulfur (S) exceeds 0.01% by weight, there is a problem in that low-temperature impact toughness is lowered due to an increase in the fraction of MnS inclusions.
Thus, in the present invention, the content of sulfur (S) was limited to 0.01% by weight or less of the total weight of the steel sheet.
chrome( Cr )
Chromium (Cr) is an element that stabilizes ferrite to improve elongation and contributes to strength improvement.
The chromium (Cr) is preferably added in a content ratio of 0.4 to 1.0% by weight of the total weight of the steel sheet. When the content of chromium (Cr) is less than 0.4 wt%, the above effects cannot be exerted properly. On the contrary, when the content of chromium (Cr) exceeds 1.0% by weight, the balance between strength and ductility may be broken.
nickel( Ni )
Nickel (Ni) fine grains and solidify in the austenite and ferrite to strengthen the matrix. Nickel (Ni) is an effective element for improving impact resistance at low temperatures.
The nickel (Ni) is preferably added in a content ratio of 0.2 to 1.0% by weight of the total weight of the steel sheet. When the nickel (Ni) content is added less than 0.2% by weight, the effect of improving the strength and the low temperature impact toughness due to the addition of nickel cannot be properly exhibited. On the contrary, when the content of nickel (Ni) is added in excess of 1.0% by weight, there is a problem of causing red brittleness and increasing the manufacturing cost.
molybdenum( Mo )
Molybdenum (Mo) contributes to improvement of strength and toughness, and also contributes to ensuring stable strength at room temperature or high temperature.
The molybdenum (Mo) is preferably added in 0.2 ~ 1.0% by weight of the total weight of the steel sheet. When the content of molybdenum (Mo) is less than 0.2% by weight, the effect of improving the strength and toughness due to the addition of molybdenum may not be properly exhibited. On the contrary, when the content of molybdenum (Mo) is added in excess of 1.0% by weight, there is a problem of lowering the weldability and increasing the yield ratio by precipitation of carbide.
aluminum( Al )
Aluminum (Al) is added for deoxidation during steelmaking. When the content of aluminum (Al) is added in a large amount of more than 0.03% by weight there is a problem that the playability is lowered.
Thus, in the present invention, the content of aluminum (Al) was added to 0.03% by weight or less of the total weight of the steel sheet.
Copper( Cu )
Copper (Cu) is added as nickel (Ni) as an element to improve the hardenability and corrosion resistance of the steel.
The copper (Cu) is preferably added in a content ratio of 0.2 to 1.0% by weight of the total weight of the steel sheet. When the content of copper (Cu) is added less than 0.2% by weight, the addition effect is not sufficiently exhibited because the content is insignificant. On the contrary, when the content of copper (Cu) exceeds 1.0% by weight, there is a problem of lowering the surface properties of the steel.
titanium( Ti )
Titanium (Ti) is a strong carbonitride-forming element that precipitates solid carbon and solid nitrogen to improve non-vitrification and processability. In particular, titanium (Ti) prevents Boron (B) from being precipitated as a nitride precipitate, and boron is present in a solid state in the steel so that boron serves to improve the hardenability of the steel.
The titanium (Ti) is preferably added at 0.01 to 0.02% by weight of the total weight of the steel sheet. When the content of titanium (Ti) is less than 0.01% by weight, there arises a problem that aging hardening occurs because of the remaining solid carbon and nitrogen employed without precipitation. On the contrary, when the content of titanium (Ti) exceeds 0.02% by weight, the playability is lowered and there is a problem of increasing the manufacturing cost without any additional effect.
Niobium ( Nb )
Niobium (Nb) combines with carbon (C) and nitrogen (N) at high temperatures to form carbides or nitrides. Niobium carbide or nitride improves the strength and low-temperature toughness of a steel sheet by suppressing crystal grain growth during rolling and making crystal grains finer.
Niobium (Nb) is preferably added in an amount of 0.005 to 0.05% by weight of the total weight of the steel sheet. When the content of niobium (Nb) is added at less than 0.005% by weight, the niobium addition effect may not be properly exhibited. If the content of niobium (Nb) exceeds 0.05% by weight, the strength and low temperature toughness due to the increase in niobium (Nb) content are no longer improved, and there is a risk that the impact toughness is lowered due to the presence of solid solution in the ferrite. .
Vanadium (V)
Vanadium (V) serves to improve the strength of the steel through the precipitation strengthening effect by the formation of precipitates.
The vanadium (V) is preferably added in a content ratio of 0.055 to 0.10% by weight of the total weight of the steel sheet. If the content of vanadium (V) is less than 0.055% by weight, the precipitation strengthening effect due to the addition of vanadium is insufficient. On the contrary, when the content of vanadium (V) exceeds 0.10 wt%, the low-temperature impact toughness deteriorates.
Boron (B)
Boron (B) is a strong hardenable element, and serves to prevent the segregation of phosphorus to improve strength. If segregation of phosphorus (P) occurs, secondary processing brittleness may occur, so that the addition of boron prevents the segregation of phosphorus to increase the resistance to processing brittleness.
The boron (B) is preferably added in an amount of 0.0001 to 0.0050% by weight of the total weight of the steel sheet. When the content of boron (B) is less than 0.0001% by weight, the added amount is insignificant, and thus the above effects cannot be exerted properly. On the contrary, when the content of boron (B) is added in excess of 0.0050% by weight, there is a problem of inhibiting the surface quality of the steel sheet by the formation of boron oxide.
Nitrogen (N)
Nitrogen (N) is an unavoidable impurity, and when it contains a large amount of more than 0.007% by weight, the solid solution of nitrogen increases to reduce the impact characteristics and elongation of the steel sheet and greatly reduce the toughness of the weld.
Thus, in the present invention, the content of nitrogen (N) was limited to 0.007% by weight or less of the total weight of the steel sheet.
Remark( Sn )
Tin (Sn) contributes to improving the strength of the steel sheet through solid solution strengthening.
The tin is preferably added in 0.0002 to 0.0015% by weight of the total weight of the steel sheet. If the amount of tin added is less than 0.0002% by weight, the effect of addition is insufficient. On the contrary, when the addition amount of tin exceeds 0.0015 weight%, there exists a problem of reducing the moldability of a steel plate.
calcium( Ca )
Calcium (Ca) is added for the purpose of improving electrical resistance weldability by inhibiting the formation of MnS inclusions by forming CaS inclusions. That is, calcium (Ca) has a higher affinity with sulfur than manganese (Mn), so CaS inclusions are formed and CaS inclusions are reduced when calcium is added. Such MnS is stretched during hot rolling to cause hook defects and the like in electrical resistance welding (ERW), so that electrical resistance weldability can be improved.
The calcium (Ca) is preferably added at a content ratio of 0.0004% by weight of the total weight. When the content of calcium (Ca) exceeds 0.0004% by weight of the total weight, there is a problem in that the generation of CaO inclusions are excessively degraded electrical resistance weldability.
Steel plate manufacturing method
1 is a flowchart showing a method of manufacturing a steel sheet according to an embodiment of the present invention.
Referring to FIG. 1, the illustrated steel sheet manufacturing method includes a slab reheating step S110, a rolling step S120, and a cooling step S130.
Reheat slab
In the slab reheating step (S110), the composition, that is, carbon (C): 0.1 to 0.2% by weight, silicon (Si): 0.6% by weight or less, manganese (Mn): 0.5 to 1.8% by weight, phosphorus (P): 0.02 % By weight, sulfur (S): 0.01% by weight or less, chromium (Cr): 0.4 to 1.0% by weight, nickel (Ni): 0.2 to 1.0% by weight, molybdenum (Mo): 0.2 to 1.0% by weight, aluminum (Al ): 0.03 wt% or less, Copper (Cu): 0.2 ~ 1.0 wt%, Titanium (Ti): 0.01 ~ 0.02 wt%, Niobium (Nb): 0.005 ~ 0.05 wt%, Vanadium (V): 0.055 ~ 0.10 wt% , Boron (B): 0.0001 ~ 0.0050% by weight, nitrogen (N): 0.007% by weight or less, tin (Sn): 0.0002 ~ 0.0015% by weight, calcium (Ca): less than 0.05% by weight and the rest of iron (Fe) and Slab plate in the state of semi-manufactured products made of unavoidable impurities is reheated to SRT (Slab Reheating Temperature): 1150 ~ 1200 ℃. The slab plate having the composition can be obtained through a continuous casting process after obtaining a molten steel of the desired composition through a steelmaking process. Through reheating of the slab sheet, the segregated components are cast again during casting.
If the slab reheating temperature (SRT) is less than 1150 ° C., there is a problem in that the segregated components are not reusable sufficiently during casting. On the contrary, when the slab reheating temperature (SRT) exceeds 1200 ° C., the austenite grain size may be increased to secure strength, and the manufacturing cost of the steel sheet may increase due to the excessive heating process.
Hot rolling
In the hot rolling step (S120), the slab plate is hot rolled.
In the hot rolling step (S120), the finish rolling temperature (FDT) is preferably 850 ~ 1050 ℃. When hot rolling is finished in the above temperature range, the structure of the steel sheet before cooling after hot rolling may become an austenite phase. If the finish rolling temperature exceeds 1050 ° C., the austenite grains are coarsened, so that the ferrite grains may not be sufficiently refined after the transformation, thereby making it difficult to secure the strength. On the contrary, when the finishing temperature is lower than 850 ° C., problems such as a mixed structure caused by abnormal reverse rolling may occur.
Cooling
In the cooling step (S130) to cool the hot rolled plate.
Cooling may be applied by air cooling.
In addition, the cooling may be a soft colling method, which is a method of cooling the surface by spraying a small amount of water at the front or rear of the cooling table. In this case, productivity can be improved by reducing the cooling time with respect to the steel plate with a relatively thick thickness.
Example
Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.
Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.
1. Preparation of specimens
The specimens according to Examples 1 to 3 and Comparative Examples 1 to 3 were produced under the composition shown in Table 1 and the process conditions shown in Table 2.
[Table 1] (unit:% by weight)
[Table 2]
2. Evaluation of mechanical properties
Table 3 shows the evaluation results of the mechanical properties of the specimen prepared according to Comparative Examples 1-2 and Examples 1-2.
[Table 3]
Referring to Tables 1 to 3, in the case of the specimen prepared according to Examples 1 to 2 it can be seen that the tensile strength (TS), yield strength (YS) and elongation (EL) satisfy all the target values.
For specimens prepared according to Examples 1 and 2, it can be seen that all of the tensile strength (TS), yield strength (YS) and elongation (EL) corresponding to the target value.
2 and 3 are graphs showing Charpy average impact absorption energy according to temperature for specimens prepared according to Examples 1 to 2 of the present invention.
2 and 3, in the case of specimens prepared according to Examples 1 and 2, it can be seen that the Charpy average impact absorption energy measured at a temperature of -60 ° C. or more has 47 J or more.
3. Corrosion resistance evaluation
Corrosion resistance was evaluated using a 5% sodium chloride solution having a pH of 6.5 to 7.2 at 25 ° C., and a corrosion rate after a predetermined time after brine spraying at 35 ° C.
To determine the corrosion rate, the weight of the specimen was measured before and after removal of the corrosion product. Here, the specimen was taped on the back, side, top, and bottom.
That is, the actual weight loss was measured, and the corrosion rate measurement and the corrosion characteristics were compared by using the following equation.
Where W is weight loss (mg), D is density (g / cm 3 ), A is exposure area (cm 2 ), and T is time (hr).
Table 4 shows the corrosion resistance results for the specimen prepared according to Comparative Examples 1 and 2 and Examples 1 and 2.
[Table 4]
4 and 5 are graphs showing the results of the salt spray test for the specimens prepared according to Examples 1-2 and Comparative Examples 1-2.
Referring to Table 4, FIG. 4 and FIG. 5, in the case of the specimens prepared according to Examples 1 and 2, the corrosion degree was similar when the specimens prepared according to Comparative Examples 1 and 2 passed 22 days.
On the other hand, in the case of the specimen prepared according to Examples 1 to 2 when 46 days have elapsed compared to the specimen prepared according to Comparative Examples 1 and 2, Examples 1 to 2 did not have a large change in the corrosion rate, In the case of Comparative Examples 1 to 2 it can be seen that the corrosion rate increased sharply.
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.
S110: Slab reheating step
S120: Hot rolling step
S130: cooling step
Claims (7)
Hot rolling the reheated plate to a finishing rolling temperature of 850 ° C. to 1050 ° C .; And
Cooling the rolled sheet material; steel sheet manufacturing method comprising a.
In the hot rolling step,
Slab Reheating Temperature (Slab Reheating Temperature) is a steel sheet manufacturing method characterized in that 1150 ~ 1200 ℃.
In the cooling step,
Cooling is a steel sheet manufacturing method characterized in that the air cooling method is applied.
In the cooling step,
Cooling is a steel sheet manufacturing method characterized in that the soft cooling (soft colling) is applied.
The steel sheet
A steel sheet having a tensile strength (TS) of 490 MPa or more, a yield strength (YS) of 355 MPa or more, and an elongation (EL) of 1% or more.
The steel sheet
Charpy average impact absorption energy at 0 ° C .: Steel sheet having 47J or more.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020120009496A KR20130088329A (en) | 2012-01-31 | 2012-01-31 | Steel sheet and method of manufacturing the steel sheet |
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020120009496A KR20130088329A (en) | 2012-01-31 | 2012-01-31 | Steel sheet and method of manufacturing the steel sheet |
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| KR20130088329A true KR20130088329A (en) | 2013-08-08 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101657421B1 (en) * | 2015-09-22 | 2016-09-13 | 현대제철 주식회사 | Chain steel and manufacturing method thereof |
| CN113585928A (en) * | 2021-07-29 | 2021-11-02 | 尤利卡（江苏）集成电气有限公司 | Damping door plate for box-type substation and machining process of damping door plate |
-
2012
- 2012-01-31 KR KR1020120009496A patent/KR20130088329A/en not_active Application Discontinuation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101657421B1 (en) * | 2015-09-22 | 2016-09-13 | 현대제철 주식회사 | Chain steel and manufacturing method thereof |
| CN113585928A (en) * | 2021-07-29 | 2021-11-02 | 尤利卡（江苏）集成电气有限公司 | Damping door plate for box-type substation and machining process of damping door plate |
| CN113585928B (en) * | 2021-07-29 | 2023-07-04 | 尤利卡（江苏）集成电气有限公司 | Damping door plate for box-type transformer substation and processing technology thereof |
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