WO2016105145A1 - 린 듀플렉스 스테인리스강 및 그 제조방법 - Google Patents
린 듀플렉스 스테인리스강 및 그 제조방법 Download PDFInfo
- Publication number
- WO2016105145A1 WO2016105145A1 PCT/KR2015/014235 KR2015014235W WO2016105145A1 WO 2016105145 A1 WO2016105145 A1 WO 2016105145A1 KR 2015014235 W KR2015014235 W KR 2015014235W WO 2016105145 A1 WO2016105145 A1 WO 2016105145A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- stainless steel
- steel
- phase
- duplex stainless
- lean duplex
- Prior art date
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/055—Cooling the moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Definitions
- the present invention relates to a lean duplex stainless steel having a ferritic-austenite-based structure and a method of manufacturing the same.
- austenitic stainless steel having good processability and corrosion resistance contains iron (Fe) as a base metal, and contains chromium (Cr) and nickel (Ni) as main raw materials, and molybdenum (Mo) and copper (Cu), etc. It is developed in various steel grades to suit various purposes by adding other elements of.
- the 300-based stainless steel having excellent corrosion resistance and workability includes expensive raw materials such as Ni and Mo.
- 200- and 400-based stainless steels have been discussed.
- the moldability and corrosion resistance is less than 300-based stainless steel.
- duplex stainless steel mixed with the austenite phase and the ferrite phase has all the advantages of the austenitic and ferritic bars, and various types of duplex stainless steel have been developed to date.
- the present invention is to control the content of the alloy components to reduce the cost, while controlling to satisfy the lamination defect energy value present in lean duplex stainless steel, lean duplex stainless steel that can ensure excellent elongation and corrosion resistance and its manufacturing method To provide.
- the present invention provides a lean duplex stainless steel and a method of manufacturing the same, which are capable of securing excellent elongation and corrosion resistance by controlling to satisfy a value of critical strain for strain induced martensite formation.
- the present invention provides a lean duplex stainless steel and a method for manufacturing the same, which can solve the problem of the large amount of nitrogen gas discharged due to the drastic reduction of the nitrogen solubility during solidification from liquid to solid phase during casting.
- Lean duplex stainless steel according to an embodiment of the present invention is a ferritic austenitic stainless steel, the austenitic lamination defect energy (SFE) value represented by the following [Formula 2] is 19 ⁇ 37, calcined organic martens It is preferable that the range of the critical strain value at which the site phase is formed is 0.1 to 0.25.
- SFE austenitic lamination defect energy
- Ni, Cu, Cr, N, Si, Mn means the total content (wt%) of each component element
- K (x) is the distribution coefficient of each component element (x)
- Equation 3 V ( ⁇ ) is the austenite phase fraction (range 0.45 ⁇ 0.75).
- K (Cr) 1.16
- K (Ni) 0.57
- K (Mn) 0.73
- K (Cu) 0.64
- K (N) and K (Si) are N and Si.
- wt%) Depending on the content (wt%) can be the following values.
- the elongation of the said stainless steel is 45% or more.
- the stainless steel is by weight, C: 0.08% or less (excluding O%), Si: 0.2 to 3.0%, Mn: 2 to 4%, Cr: 18 to 24%, Ni: 0.2 to 2.5%, N: 0.15 ⁇ 0.32%, Cu: 0.2-2.5%, balance Fe and other unavoidable impurities.
- the stainless steel may further include at least one of W: 0.1 to 1.0% and Mo: 0.1 to 1.0% by weight.
- the stainless steel may further include at least one of Ti: 0.001 to 0.1%, Nb: 0.001 to 0.05%, and V: 0.001 to 0.15% by weight.
- a method of manufacturing a lean duplex stainless steel is a method of manufacturing a ferritic austenitic lean duplex stainless steel, the process of preparing molten steel;
- the molten steel is treated with stainless steel so that the lattice defect energy (SFE) value of the austenite phase represented by the following [Formula 2] is 19 to 37, and the critical strain value at which the calcined organic martensite phase is formed is 0.1 to 0.25. It may include the process of doing.
- SFE lattice defect energy
- Ni, Cu, Cr, N, Si, Mn means the total content (wt%) of each component element
- K (x) is the distribution coefficient of each component element (x)
- Equation 3 V ( ⁇ ) is the austenite phase fraction (range 0.45 ⁇ 0.75).
- the process of treating the molten steel to stainless steel the step of temporarily storing the molten steel in a tundish while maintaining a high temperature 10 ⁇ 50 °C higher than the theoretical solidification temperature; Injecting molten steel into the mold in the tundish and passing the mold first while maintaining a cooling rate of 500 to 1500 ° C./min;
- the first cooling may include a step of secondary cooling while drawing molten steel having a solidified shell formed therein through the segment.
- a ratio of air to cooling water is 1.0 to 100 to 125 l / kg ⁇ min to the surface of the cast steel. It may further comprise a third step of cooling by spraying to mix to ⁇ 1.2.
- the process of treating the molten steel with stainless steel including the step of solidifying the molten steel while passing between a pair of casting rolls to produce a strip, the nitrogen solubility limit contained in the molten steel in the step of producing the strip
- the above nitrogen may be discharged to the outside of the solidification shell through the casting roll.
- a plurality of gas discharge channels formed in the casting roll used in the step of manufacturing the strip is formed with a width 50 ⁇ 500 ⁇ m, depth 50 ⁇ 300 ⁇ m, the interval between the adjacent gas discharge channels are 100 ⁇ 1000 ⁇ m.
- the molten steel is in weight%, C: 0.08% or less (excluding O%), Si: 0.2 to 3.0%, Mn: 2 to 4%, Cr: 18 to 24%, Ni: 0.2 to 2.5%, N: 0.15 to 0.32%, Cu: 0.2 to 2.5%, balance Fe and other unavoidable impurities.
- the molten steel may further include at least one or more of W: 0.1 to 1.0% and Mo: 0.1 to 1.0% by weight.
- the molten steel may further include at least one of Ti: 0.001 to 0.1%, Nb: 0.001 to 0.05%, and V: 0.001 to 0.15% by weight in the process of preparing the molten steel.
- the content of the high-value element Ni, Si and Cu alloy components it is possible to significantly reduce the resource savings and raw material costs, in particular to ensure the corrosion resistance and excellent elongation higher than the equivalent level of STS 304 It can be sufficiently used as an alternative to the 200 series, 300 series (STS 304, 316) used for molding.
- the molten steel temperature and the cooling rate may be controlled to suppress pinholes generated inside the cast steel.
- 1 is a view showing a critical strain value of the plastic organic martensite phase is formed by the stress-strain curve of the invention steel and the comparative steel according to an embodiment of the present invention
- 2A and 2B are representative transmission electron microscopic photographs of comparative steels and inventive steels according to an embodiment of the present invention.
- FIG. 4 is a view schematically showing a continuous casting method manufacturing process of lean duplex stainless steel according to an embodiment of the present invention
- FIG. 5 is a view schematically showing a process for manufacturing a strip casting method of lean duplex stainless steel according to an embodiment of the present invention.
- FIG. 6 is a view schematically showing a casting roll required in a strip casting method of manufacturing lean duplex stainless steel according to an embodiment of the present invention.
- FIG. 9 is a photograph of surface defects of comparative material F.
- the present invention relates to a lean duplex stainless steel having a ferrite-austenitic structure
- the ferrite-austenite structure referred to in the present invention means that the ferrite phase and the austenite phase occupy most of the structure, and the stainless steel is This does not mean that it is formed only of the ferrite phase and the austenite phase.
- the ferrite phase and the austenite phase occupy most of the structure, which means that the sum of the ferrite phase and the austenite phase accounts for 90% or more of the stainless steel-forming structure, except for the ferrite phase and the austenite phase.
- the austenitic martensite phase may be occupied.
- 1 is a view showing the critical strain value of the plastic organic martensite phase formation in the stress-strain curve of the inventive steel and the comparative steel according to the embodiment of the present invention.
- the present invention is by weight (unless otherwise specified, the content of the component is by weight), C: 0.08% or less (excluding O%), Si: 0.2-3.0%, Mn: 2-4%, Cr: 18 ⁇ 24%, Ni: 0.2 to 2.5%, N: 0.15 to 0.32%, Cu: 0.2 to 2.5%, lean duplex with biphasic structure formed of ferrite phase and austenite phase including residual Fe and other unavoidable impurities Stainless steel may be the target.
- the lean duplex stainless steel may further include at least one of W: 0.1 to 1.0%, Mo: 0.1 to 1.0%, Ti: 0.001 to 0.1%, Nb: 0.001 to 0.05%, and V: 0.001 to 0.15%. have.
- C is an austenite phase forming element and is an effective element for increasing the material strength by solid solution strengthening.
- carbide-forming elements such as Cr, which is effective for corrosion resistance at the ferrite-austenite phase boundary, thereby lowering the Cr content around grain boundaries to reduce corrosion resistance. It is preferable to add in the range of% or less.
- Si is partially added for the deoxidation effect, and is an element that is concentrated in the ferrite phase during annealing heat treatment as a ferrite phase forming element. Therefore, 0.2% or more should be added to ensure proper ferrite phase fraction.
- excessive addition of more than 3.0% rapidly increases the hardness of the ferritic phase, affecting the lowering of the elongation of the two-phase steel, making it difficult to secure the austenite phase to ensure sufficient elongation.
- the Si content is preferably limited to 0.2 to 3.0%.
- Mn is an element which increases the deoxidizer and the nitrogen solubility, and is an austenite phase forming element and can be used for replacing expensive Ni.
- Mn is added a lot, it has an effect on the solubility of nitrogen, but when combined with S in steel to form MnS, the corrosion resistance is poor. Therefore, when the content is added in excess of 4% it is difficult to ensure the corrosion resistance of the 304 steel level.
- the Mn content is less than 2%, it is difficult to secure an appropriate austenite phase fraction even if the austenitic phase forming elements Ni, Cu, N, etc. are adjusted. I can't get employment. Therefore, the content of Mn is preferably limited to 2 to 4%.
- the content of Cr is preferably limited to 18 to 24%.
- Ni is an austenite stabilizing element and plays a major role in securing the austenite phase of duplex stainless steel.
- the austenitic phase forming elements Mn and N may be increased to sufficiently maintain the balance of phase fraction due to the reduction of Ni.
- the addition of a large amount of Ni increases the austenite phase fraction, making it difficult to secure an appropriate austenite phase ratio.
- the content of Ni is preferably limited to 0.2 to 2.5%.
- N is an element that greatly contributes to stabilization of the austenite phase together with Ni in duplex stainless steel, and is one of the elements in which thickening occurs in the austenite phase due to the fast diffusion rate in the solid phase during annealing.
- an increase in N content may induce an increase in corrosion resistance and higher strength.
- the solubility of N changes with the amount of Mn added. When the N content is more than 0.32% in the Mn range of the present invention, it becomes difficult to stably manufacture the steel due to surface defects caused by blow holes, pin holes, etc. during casting due to the excess of nitrogen solubility. .
- the N content is preferably limited to 0.15 to 0.32%.
- Cu is an austenite stabilizing element together with Mn, Ni, and N, and it is preferable to lower the Cu content which plays the same role as Ni in order to reduce cost. However, it is preferable to add 0.2% or more in order to secure sufficient austenite phase stability so as to suppress excessive calcined organic martensite formation generated during cold working. On the other hand, if the Cu content is more than 2.5%, it becomes difficult to process the product by hot brittle, the Cu content is preferably adjusted to 0.2 ⁇ 2.5%.
- W and Mo are austenite phase forming elements and elements that improve corrosion resistance, and are elements that promote the formation of intermetallic compounds at 700 to 1000 ° C. during heat treatment to cause deterioration of corrosion resistance and mechanical properties.
- W and Mo when their content exceeds 1%, can lead to a sharp decrease in corrosion resistance and especially elongation due to the formation of intermetallic compounds.
- 0.1% or more may be added in order to exhibit an improvement in corrosion resistance. Therefore, the content of W and Mo is preferably limited to 0.1 to 1.0%, at least one or more of W and Mo may be contained.
- Ti, Nb, and V are elements that form nitrides by reacting with nitrogen, and crystallized as TiN, NbN, VN, etc. in molten steel and act as nucleation sites in the ferrite phase during solidification, so that sufficient solidification may proceed even if the cooling rate increases. Suppresses the fracture of the slabs.
- these elements are sufficiently dissolved in the manufacturing process, that is, during reheating or hot rolling, and upon cooling, they react with carbon and nitrogen to form carbonitrides, thereby suppressing the formation of Cr carbides, thereby improving corrosion resistance.
- it is an element that suppresses Cr carbide formation at the heat affected zone during welding.
- the Ti content is preferably limited to 0.001 to 0.1%, Nb: 0.001 to 0.05%, and V: 0.001 to 0.15%, and at least one of Ti, Nb, and V may be contained.
- the present invention maintains excellent elongation and corrosion resistance by controlling the stacking fault energy by adjusting the content, distribution coefficient and phase fraction of the alloying elements.
- [Formula 1] is a formula for deriving the lamination defect energy by using the content of the entire component in the alloy.
- the present inventors have measured and calculated the lamination defect energy of the present invention steel in various ways, and as a result, the component content of the austenitic structure rather than calculating the lamination defect energy using only the component content of the entire alloy composition as shown in [Equation 1].
- the calculations can be used to more accurately predict the properties of alloys.
- the calculation of the stacking fault energy considering the interdistribution coefficient of alloying elements is more approximation to the actually measured stacking fault energy value than to calculate the stacking fault energy using only the component content of the whole alloy composition. It was found that it can.
- Ni, Cu, Cr, N, Si, Mn means the total content (wt%) of each component element.
- K (x) is a distribution coefficient of each component element (x), and is represented by the following [Formula 3].
- Applicants have determined the distribution coefficients for each alloying element in various annealing conditions and alloy systems utilizing Fe-EPMA and FE-TEM more accurate than EDAX analysis by conventional scanning electron microscopy. At this time, it was confirmed that the distribution coefficients for most of the alloying elements were not changed according to the temperature change in the hot or cold annealing temperature range of 900 to 1200 ° C.
- V ( ⁇ ) is an austenite phase fraction
- austenite phase fraction is defined by the following equation
- V (?) Is a ferrite phase fraction
- V (?) Has a range of 0.45 to 0.75.
- the stacking fault energy of the austenite phase is known to control the deformation mechanism of the austenite phase.
- the stacking defect energy of the austenite phase represents the degree to which the plastic deformation energy added from the outside contributes to the deformation of the austenite phase in the case of the single phase austenitic stainless steel.
- the lower the lamination defect energy the higher the degree of formation of the calcined organic martensite phase which forms the epsilon martensite phase in the austenite phase and contributes to the work hardening of the steel. If the lamination defect energy is moderate, mechanical twins are formed on the austenite.
- a plastic organic martensite phase is formed at the intersection of these twins, and the applied plastic strain energy mechanically causes a phase change, causing a transformation from an austenite phase to a martensite phase.
- a calcined organic martensite phase is formed except for the difference between the intermediate phase (epsilon martensite phase or mechanical twin) in a fairly wide range.
- the calcined organic martensite phase is formed after the epsilon martensite phase is formed on the austenite phase, or the calcined organic martensite phase is formed after the mechanical twins are formed on the austenite phase.
- the present inventors corrected the calculation equation as shown in Equation 2 in consideration of the distribution coefficient of the alloy element distributed on the austenite after various manufacturing processes and heat treatment.
- the epsilon martensite phase was first formed as an intermediate phase, and a martensite phase was formed at the intersection of the formed epsilon martensite phase.
- these martensite phases were formed rapidly at the beginning of deformation, and the phenomenon of elongation lowered by rapid work hardening appeared.
- the lamination defect energy of the austenite phase calculated using the corrected formula exceeds 37, it was confirmed by the transmission electron microscope that the formation of the martensite phase was not observed after plastic deformation. Therefore, it can be seen that the lamination defect energy of the preferred austenite phase ranges from 19 to 37.
- the lean duplex stainless steel according to the present invention is preferably formed of 45 to 75% austenite phase and 25 to 55% ferrite phase by volume fraction.
- the austenite phase fraction is less than 45%, excessive thickening of the austenite forming elements on the austenite phase occurs during annealing.
- the austenite phase is sufficiently stable to suppress the plastic organic martensite phase transformation generated during deformation, and the amount of austenite phase due to sufficient solid solution of the alloying element is increased, thereby ensuring sufficient tensile strength of the material.
- the austenite phase fraction is preferably 45% or more.
- the austenite phase fraction is more than 75%, surface cracks or the like occur during hot rolling, resulting in a decrease in hot workability, and loss of properties as a two-phase structure steel. Therefore, the austenite phase fraction is preferably 75% or less.
- the critical strain value at which the calcined organic martensite phase is formed during cold working or tensile strain is maintained at 0.1 to 0.25.
- the critical strain amount at which the calcined organic martensite phase is formed was measured from the inflection point of the stress-strain curve, which typically represents the strain value at the time of contributing to the work hardening of the martensite phase in the steel in which the calcined organic martensite phase is formed.
- the work hardening rate it gradually decreases as the tensile strain progresses after yielding, and then an inflection point is formed at the point where the plastic organic martensite phase is generated and starts to contribute to the work hardening. And when tensile strain advances by the strain more than an inflection point and at the same time, formation of the plastic organic martensite phase increases, the work hardening rate increases again.
- the critical strain value is a strain value at which the plastic organic martensite is formed and starts to contribute to work hardening, and means a strain value at a point corresponding to an inflection point in the stress-strain curve obtained by a tensile test. Means the point where the second derivative of the curve becomes "0".
- the calcined organic martensite phase is formed too easily during deformation, and the ductility of the material is drastically lowered due to rapid work hardening at the beginning of the deformation.
- the calcined organic martensite phase is formed too late, that is, when the value of the critical strain is more than 0.25, a decrease in elongation occurs due to the occurrence of necking, which is a local stress concentration due to lack of work hardening of the material. therefore.
- the range of the critical strain value at which the calcined organic martensite phase is formed is 0.1 to 0.25.
- the stability control of the austenite phase is very important in the lean duplex stainless steel according to the present invention.
- the calcined organic martensite phase is a hard phase formed when the unstable austenite phase is deformed, which causes work hardening and contributes to an increase in elongation of the steel.
- steel which is a duplex stainless steel composed of an austenitic phase and a ferrite phase
- the stability of the austenitic phase can be adjusted by appropriate distribution of alloying elements.
- a method of rapid solidification was used as a method for enabling proper distribution of alloying elements.
- the austenite phase and the ferrite phase formed coagulate non-equilibrium because the time for diffusion to occur in the solid phase is insufficient.
- stability of the austenite phase can be controlled to a sufficiently desired range by utilizing the distribution of the alloying elements generated. In order to achieve this, by maintaining a high content of nitrogen in the solid phase diffusion rate higher than usual.
- the alloy was designed so that most of the nitrogen segregated on the austenite phase.
- the specimens were prepared using molten steel whose content of components was adjusted, followed by hot rolling, hot rolling annealing, and cold rolling annealing to adjust the phase ratio of the material, thereby measuring elongation and corrosion resistance.
- Tensile test pieces were measured by adjusting the tensile strain rate at a rate of 1.0 ⁇ 10 ⁇ 3 / s at room temperature after processing a specimen of ASTM-sub size parallel to the rolling direction.
- Table 1 shows the alloy composition (wt%) for the experimental steel.
- the difference between Gibbs free energy is calculated by calculating the thermodynamic Gibbs free energy difference when the crystal structure of a phase having the same component is FCC austenite and BCC martensite.
- G M -G ⁇ This is because a calcined organic martensite phase is formed only when the condition of ⁇ 0 (Gibs energy on martensite phase-Gibbs energy on austenite phase) is satisfied.
- the difference between the Gibbs free energy and the formation of the calcined organic martensite phase is closely related. For example, when the Gibbs free energy difference ( ⁇ G) is positive, no calcined organic martensite phase is formed, and the Gibbs free energy difference ( ⁇ G When () is negative may mean that the calcined organic martensite phase is formed.
- the Gibbs free energy of austenite phase and martensite phase it was calculated using commercial software FACTsage 6.4 (Thermfact and GTT-Technologies).
- the components of the alloy present in the austenite phase among the steels present in the two phases of the ferrite phase and the austenite phase must be known, and the amount of the alloying components present in the austenite phase is given in the present invention. It can be calculated using the distribution coefficient and the phase fraction.
- X component on austenite phase X / [K (X) -K (X) ⁇ V ( ⁇ ) + V ( ⁇ )] (X: total X component, K (X): partition coefficient, V ( ⁇ ): austenite phase fraction).
- phase fraction varies depending on the alloy composition and the heat treatment temperature.
- Table 2 shows the ferrite and austenite phase fractions when the comparative steels 1 to 5 and the inventive steels 1 to 10 were heat treated at 1100 ° C., respectively.
- the phase fraction of ferrite is in the range of about 25 to 55%
- the austenite phase fraction is in the range of 45 to 75%.
- Comparative Steel 2 when the heat treatment at 1100 °C, the phase fraction of the ferrite appeared to be 83%, respectively, at this time, the austenite phase fraction also appears to be 17%, respectively. That is, it can be seen that Comparative Steel 2 does not fall within the range of the ferrite and austenite phase fractions of the present invention.
- Figure 1 is a representative nominal strain-nominal stress comparison curve obtained in the present invention, which is the result of the tensile test after heat treatment to each material at 1100 °C.
- Comparative Steel 1 In the case of Comparative Steel 1, the calcined organic martensite phase was not formed during uniform deformation. As a result, there was no calcined organic martensite phase capable of suppressing local necking due to work hardening during plastic deformation, and thus a decrease in elongation was predicted. In comparison, comparative steel 1 exhibited a very low elongation of about 31%.
- Comparative Steel 3 is a two-phase stainless steel composed of a ferrite phase and an austenite phase, but its elongation is inferior to about 35%.
- the critical strain value when the critical strain value is less than 0.1, the plastic organic martensite phase is formed rapidly, resulting in a sharp decrease in elongation due to the hardening of the material by the rapid work hardening. If the critical strain value is more than 0.25, the calcined organic martensite phase is formed too late to prevent local necking of the material caused by the strain. Therefore, in the case of the lean duplex stainless steel composed of the austenitic phase-ferrite phase of the present alloy system, when the range of the critical strain value at which the calcined organic martensite phase is formed is 0.1 to 0.25, the elongation of the existing duplex steel is 30% or less.
- the value of the critical strain at which the calcined organic martensite phase is formed during cold working is preferably 0.1 to 0.25.
- FIG. 2A and 2B show transmission electron microscope microstructures of Comparative Steel 1 and Inventive Steel 1, respectively.
- Comparative Steel 1 As shown in FIG. 2A, a strain band due to deformation and a mechanical twin are observed, but it is understood that the calcined organic martensite phase is not observed.
- the inventive steel 1 it can be seen that the calcined organic martensite phase is formed at the intersection of the strain band or the mechanical twin as shown in FIG. 2B. (The calcined organic martensite phase is indicated by an arrow.)
- FIG. 3 is a graph showing the relationship between the elongation and the value of the critical strain in which the calcined organic martensite phase is formed. Referring to the stress-strain curve of FIG. 1, the result of measuring the critical strain in which the martensite phase is formed is shown in FIG. 3. Shown in
- the lean duplex stainless steel according to the present invention can be produced both in a continuous casting method and a strip casting method to solve the problem of nitrogen gas generation or discharge in accordance with the difference in nitrogen solubility when solidified in the liquid phase.
- Figure 4 is a schematic view showing a continuous casting method manufacturing process of lean duplex stainless steel according to an embodiment of the present invention.
- Lean duplex stainless steel according to an embodiment of the present invention is manufactured in a conventional playing equipment 100 in which ladle 110, tundish 120, mold 130, a plurality of segments 140 are sequentially arranged. .
- the rear end of the segment 140 is further provided with injection means 150 for injecting a mixture of air and cooling water.
- the molten steel having the alloying components shown above is prepared and moved to the ladle 110, and then temporarily placed in the tundish 120 using the shrouding nozzle 111. Save it. At this time, the molten steel temporarily stored in the tundish 120 is preferably maintained 10 ⁇ 50 °C higher than the theoretical solidification temperature.
- the difference between the molten steel temperature and the theoretical solidification temperature in the tundish 120 is ⁇ T (°C)
- the lower limit is 10 °C
- the upper limit is 50 °C
- ⁇ T is lower than the lower limit of 10 °C molten steel in the tundish 120
- the solidification of (M) can proceed, causing problems in continuous casting, and when ⁇ T exceeds the upper limit of 50 ° C, the solidification rate is slowed during solidification, resulting in a coagulation structure that becomes coarse. This is because it is easy to occur.
- the molten steel (M) is injected into the mold 130 by using the immersion nozzle 121 in the tundish 120.
- the mold 130 is primarily cooled by passing the mold 130 while maintaining the cooling rate of the molten steel (M) at 500 ⁇ 1500 °C / min.
- the cooling rate is less than 500 ° C / mim
- the amount of cooling (primary cooling) in the mold 130 and the cooling (secondary cooling) in the segment 140 during the continuous casting is reduced, thereby during casting
- the heat transfer of the cast (S) is delayed, the strength of the cast slag solidification layer is lowered to cause the phenomenon of the bulging (casting) of the cast is caused to deteriorate the operation and quality.
- the cooling rate is controlled to more than 1500 °C / min, very advantageous from the viewpoint of nitrogen pinhole, but the continuous operation is impossible due to the limitation of the continuous casting equipment at present, and the solute remaining between dendrite during continuous casting It takes less time for elemental segregation to diffuse, causing surface cracks in the cast. Due to this phenomenon, there is a problem in that an overlapping phenomenon in which the cast shell (external shell) is temporarily broken inside the mold 130 occurs. Therefore, it is preferable to set the cooling rate at the time of primary cooling in the mold 130 at 500-1500 degreeC / min.
- the molten steel (M) having a solidified shell that is, the cast steel (S) is drawn to the segment 140 to perform secondary cooling, wherein the cooling water of 0.25 to 0.35l / kg is injected into the cast steel (S). It is desirable to.
- the reason for limiting the specific quantity in the segment 140 is as follows.
- the coagulated structure can be finely formed, but if the nonaqueous water exceeds 0.35 l / kg, segregation between the solidified structures during the continuous casting process occurs. Since the impurity is less time to diffuse, it is present as a sigma and cracks on the surface of the cast. In addition, since residual stress as well as cracks due to thermal stress are excessively generated on the surface, surface cracks are generated during the grinding of the slab.
- the coagulation structure becomes excessive and the problem of coagulation cracks is generated by the sigma phase generated at the grain boundary, and the strength of the slag coagulation shell during the continuous casting decreases, thereby causing the slab bulging ( It causes a problem of cracking due to bulging.
- the specific amount range in the segment 140 is preferably 0.25 to 0.35 l / kg.
- FIG. 1 The tertiary cooling is continuously drawn to the segment 140 while cooling water of 100 to 125 l / kg ⁇ min with respect to the entire surface of the cast steel S in the range where the surface temperature of the cast steel S is 1100 to 1200 ° C.
- the ratio (air / cooling water) is 1.0 to 1.2 so that the mixture is sprayed and cooled.
- the tertiary cooling is to control to ensure a uniform scale on the surface of the cast (S).
- S cast
- the reason is that in the case of lean duplex stainless steel, the amount of oxidation in the heating furnace is very small and the lubrication effect by the scale during hot rolling is small, so that it is very difficult to reduce surface cracks. Therefore, in order to prevent temperature reduction due to contact between the roll and the steel sheet during rolling and to reduce surface friction by preventing friction between the roll and the steel sheet, a dense and thick scale should be formed on the surface of the steel sheet, and it should not be easily peeled off during rolling.
- the reason for limiting the surface temperature of the cast steel (S), the specific amount of the cooling water and the ratio of the cooling water and the air (air / cooling water) as described above is the desired level on the surface of the cast steel (S) when the above conditions are not satisfied (approximately 35 This is because no scale is formed with a thickness of ⁇ ⁇ ⁇ 2 ⁇ ⁇ , and the resulting scale is not formed uniformly.
- lean duplex stainless steel having a composition according to the present invention was produced while changing the molten steel temperature in the tundish, the cooling rate in the mold, and the specific water quantity in the secondary cooling zone as shown in [Table 4]. Crack incidence of the pinhole and the surface of the cast steel are also shown in Table 4. At this time, the pinhole occurrence of the cast steel was observed after grinding the surface of the slab about 0.5mm.
- the cooling rate in the mold was within the scope of the present invention, and no pinholes due to nitrogen were generated inside the cast steel.
- bulging did not occur during casting because the specific quantity was greater than the range of the present invention, but thermal stress acted on the surface of the cast steel, causing cracking.
- the specific water content of the secondary cooling zone was smaller than the range of the present invention, and cracking occurred on the surface of the cast steel as bulging occurred on the cast steel. As a result, linear defects occurred on the hot rolled coil surface due to the formation of local excessive scale during hot rolling.
- the comparative material I and the comparative material J, the cooling rate in the mold is lower than the range of the present invention, severe pinholes were generated in the cast.
- the surface of the cast slab is good in the specific quantity of the secondary cooling stand in the scope of the present invention, a large amount of linear defects occurred during hot rolling due to the pinhole present in the cast slab.
- Figure 7 is a tissue photograph of the comparative material I and the invention material A prepared according to the continuous casting method of the present invention
- Figure 8 is a surface defect photograph of the comparative material H prepared according to the continuous casting method of the present invention
- the comparative material I can confirm that a large amount of pinhole occurs.
- the surface of the hot rolled coil was observed after hot rolling the comparative material H, which is relatively good in generating pinholes, and a large amount of pinhole defects elongated in the rolling direction were observed.
- FIG. 9 when the surface of the hot rolled coil was observed after hot rolling the comparative material F, a large amount of cast crack surface defects were observed.
- the austenite phase and the ferrite phase are suppressed from occurrence of cracking and bulging during pinhole and casting by appropriately controlling the cooling rate in the mold and the specific quantity of the secondary cooling zone during continuous casting according to the present invention. It was confirmed that not only the excellent cast quality of lean duplex stainless steel can be obtained but also stable continuous casting operation.
- composition according to the present invention while changing the cooling water amount, injection time, air / coolant ratio, cast surface temperature of the lean duplex stainless steel made of primary cooling and secondary cooling in the third cooling as shown in Table 5 Cast steel was produced, and as a result, the thickness and uniformity of the scale are shown together in [Table 5].
- the cooling water is 100 to 120 L / kg ⁇ min for 20 to 30 minutes. It can be seen that the scale becomes very uniform and thick when spraying.
- the thickness of the scale layer was increased as the amount of air was sufficient. Accordingly, in order to form a scale layer having a desired thickness, it is preferable to maintain the ratio of air to cooling water (air / cooling water) to 1.0 or more. However, if the ratio of air exceeds the upper limit of 1.2, a sufficient scale layer can be obtained, but there is a concern that the entire cooling water system will be disturbed.
- spraying the optimum amount of coolant and air ratio and the optimal amount of coolant at the optimal spraying position in the cooling spray process can optimize the formation of the scale, improve the surface quality, and minimize the cost of the flaw removal process. It can add value.
- FIG 5 is a view schematically showing a strip casting method of manufacturing lean duplex stainless steel according to an embodiment of the present invention
- Figure 6 is a schematic view of the nitrogen discharge channel formed in the casting roll of the present invention.
- Lean duplex stainless steel according to an embodiment of the present invention is a ladle 210, tundish 220, a pair of casting rolls 230, in-line roller 260, winding rolls 270 are usually disposed sequentially Is produced in strip casting equipment 200.
- the gas discharge channel 231 is formed on the surface of the casting roll 230.
- molten steel (M) having the above-described alloying components is prepared and moved to the ladle 210, and then the tundish 220 is formed using the shrouding nozzle 211. Save it temporarily). Then, while passing between the pair of casting rolls 230 through the injection nozzle 221 to solidify to produce a strip (S), the produced strip (S) is in-line roller continuously disposed with the casting roll (230) It is rolled at 260 and wound up by the winding roll 270.
- the upper portion of the casting roll 230 is equipped with a manifold shield 250 to prevent the molten surface is in contact with the air to be oxidized, the inside of the manicus shield 250 is injected appropriate gas is properly oxidized The prevention atmosphere is formed.
- the molten steel M is rolled through the inline roller 260 while exiting the roll nip where a pair of casting rolls 230 meet, and then undergoes a heat treatment process and a cold rolling process, and thus a strip S of 10 mm or less. It is manufactured by.
- twin-roll strip caster for directly manufacturing the strip (S) of 10 mm or less described above is an internal water-cooled casting roll (twin-drum) rotating in opposite directions at high speed through the injection nozzle 250.
- the molten steel (M) is supplied between the rolls (230) and the side dams (side dams) 240, and a large amount of heat is released through the surface of the casting roll 230, which is water-cooled, to rapidly cool the molten steel and crack a thin plate having a desired thickness. It is manufactured to improve the error rate without.
- molten steel (M) molten steel
- the surface of the casting roll 230 is an example. By forming a nitrogen discharge channel 231 in the molten steel was discharged nitrogen above the solid solution limit.
- the gas discharge channel 231 is preferably formed on the surface of the casting roll 230 to enable nitrogen discharge during casting.
- the gas discharge channel 231 is a fine channel such that only nitrogen gas may be discharged without the molten steel M passing therethrough.
- the gas discharge channel 231 may be formed in various ways in the casting roll 230, is formed in the circumferential direction on the surface of the casting roll 230, the outer side of the casting roll 230 in accordance with the rotation of the casting roll 230 Nitrogen gas can be guided and discharged in the direction.
- the gas discharge channel 231 corresponds to a fine channel having a width of 50 to 500 ⁇ m and a depth of 50 to 300 ⁇ m, and a plurality of gas discharge channels 231 are formed in the circumferential direction of the casting roll 230, and the gas discharge channels adjacent to each other ( The spacing between 231) is preferably formed to about 100 ⁇ 1000 ⁇ m.
- the shape, structure, and application position of the gas discharge channel 231 may be variously modified as long as it can fulfill its function.
- the contact area between the casting roll 230 and the molten steel (M) passing through the casting roll 230 may be reduced, to prevent this It is preferable that protrusions and protrusions are formed on the casting roll surface. Such irregularities have an average size of 15 to 25 ⁇ m.
- Comparative Example 1 is to cast a molten steel having a specific composition using a general continuous casting method
- Comparative Example 2 is to cast a molten steel having a specific composition using a general strip casting (fast casting) method
- Examples 1 to Example 5 is cast in a strip casting process using a casting roll to discharge nitrogen above the solid solution limit in the molten steel.
- Comparative Example 1 was confirmed that no pores were generated in the cast steel because nitrogen was not discharged during the continuous casting process.
- Comparative Example 2 was confirmed that the pores were generated in the strip because nitrogen is not discharged during the strip casting process of the general method.
- the nitrogen composition of the high ductility lean duplex stainless steel of the present invention is in the range of 1500 to 3200 ppm.
- the process of solidifying molten steel from the liquid phase to the solid phase proceeds in the order of liquid phase-> liquid phase + delta-> delta-> delta + austenite.
- the nitrogen solubility is about 1164ppm. Employment gaps of about 836 to 1836 ppm occur.
- some of the supersaturated nitrogen in the liquid phase gas (gas) during solidification to form a variety of pores in the interior of the solidified material, as well as to form a plurality of pores in the coagulation cell formed on the material surface.
- Example 1 to Example 5 is a strip casting process according to the present invention, it was confirmed that no pores were generated in the strip due to the nitrogen discharge during the process.
- segment 150 injection means
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
- Continuous Casting (AREA)
Abstract
Description
강종 | C | Cr | Ni | Mn | Si | Cu | N | Mo | W |
비교강1 | 0.025 | 21.84 | 2.51 | 1.76 | 0.54 | 0.47 | 0.19 | 0.58 | - |
비교강2 | 0.021 | 20.3 | 0.198 | 5.05 | 0.217 | - | 0.102 | - | - |
비교강3 | 0.048 | 19.97 | - | 3.02 | 0.201 | 1 | 0.284 | - | - |
비교강4 | 0.041 | 23.1 | 0.3 | 3.2 | 2.9 | 0.55 | 0.15 | - | - |
비교강5 | 0.003 | 19.8 | 2.4 | 1.7 | 0.3 | 1.6 | 0.28 | - | - |
발명강1 | 0.051 | 19.87 | 0.5 | 2.91 | 0.865 | 1 | 0.24 | - | - |
발명강2 | 0.05 | 20.12 | 0.205 | 3.03 | 2 | 0.8 | 0.234 | - | - |
발명강3 | 0.021 | 19.9 | 0.8 | 3.05 | 0.6 | 1.04 | 0.261 | - | - |
발명강4 | 0.052 | 19.7 | 1.01 | 3.1 | 1.2 | 2 | 0.256 | - | - |
발명강5 | 0.051 | 21 | 1.02 | 3.02 | 1.1 | 2.03 | 0.254 | - | - |
발명강6 | 0.034 | 20 | 1.51 | 3 | 1.95 | 1.5 | 0.251 | - | - |
발명강7 | 0.049 | 19.95 | 1.95 | 2.7 | 0.9 | 2.02 | 0.251 | - | - |
발명강8 | 0.05 | 19.95 | 1.01 | 2.97 | 2.6 | 1 | 0.235 | - | - |
발명강9 | 0.0514 | 19.93 | 1.04 | 2.96 | 1.53 | 1 | 0.32 | - | 0.9 |
발명강10 | 0.047 | 21.33 | 1.02 | 3.04 | 1.53 | 1 | 0.23 | - | 0.47 |
강종 | 페라이트 상분율, % | 오스테나이트 상분율, % |
비교강1 | 51 | 49 |
비교강2 | 83 | 17 |
비교강3 | 35 | 65 |
비교강4 | 54 | 46 |
비교강5 | 41 | 59 |
발명강1 | 45 | 55 |
발명강2 | 37 | 63 |
발명강3 | 40 | 60 |
발명강4 | 38 | 50 |
발명강5 | 28 | 53 |
발명강6 | 33 | 67 |
발명강7 | 42 | 58 |
발명강8 | 47 | 53 |
발명강9 | 42 | 58 |
발명강10 | 48 | 52 |
강종 | 분배를 고려하지 않은 적층결함 에너지[식 1], mJ/m2 | 분배를 고려한오스테나이트상의 적층결함 에너지[식 2], mJ/m2 | 깁스자유에너지 차이 | 소성 유기 마르텐사이트상 형성 유무 | 임계변형 값 | 연신율, % |
비교강1 | 24.94 | 33.3 | 양수 | 무 | - | 31 |
비교강2 | 15.53 | 33.23 | 음수 | 유 | 0.29 | 38 |
비교강3 | 26.21 | 30.87 | 음수 | 유 | 0.07 | 35 |
비교강4 | 10.51 | 17.88 | 음수 | 유 | 0.08 | 33 |
비교강5 | 31.62 | 37.75 | 양수 | 무 | - | 36 |
발명강1 | 17.51 | 23.47 | 음수 | 유 | 0.12 | 52 |
발명강2 | 19.33 | 25.60 | 음수 | 유 | 0.143 | 49 |
발명강3 | 25.59 | 31.54 | 음수 | 유 | 0.24 | 48 |
발명강4 | 24.93 | 33.17 | 음수 | 유 | 0.238 | 53 |
발명강5 | 24.20 | 32.03 | 음수 | 유 | 0.219 | 51 |
발명강6 | 22.89 | 28.62 | 음수 | 유 | 0.167 | 59 |
발명강7 | 27.28 | 33.37 | 음수 | 유 | 0.22 | 57 |
발명강8 | 19.33 | 27.40 | 음수 | 유 | 0.182 | 50.5 |
발명강9 | 25.49 | 32.78 | 음수 | 유 | 0.24 | 52 |
발명강10 | 20.96 | 28.59 | 음수 | 유 | 0.189 | 54 |
구분 | 턴디쉬에서 용강 과열도 (oC) | 주형에서의냉각속도 (oC/min) | 2 냉각대의비수량 (ℓ/kg) | 핀홀발생 정도 | 연주 주편표면 크랙 발생 정도 |
발명재 A | 15 | 1350 | 0.29 | 없음 | 없음 |
발명재 B | 20 | 1100 | 0.32 | 없음 | 없음 |
발명재 C | 15 | 1100 | 0.27 | 없음 | 없음 |
발명재 D | 25 | 850 | 0.29 | 없음 | 없음 |
발명재 E | 22 | 550 | 0.3 | 없음 | 없음 |
비교재 F | 19 | 1100 | 0.4 | 없음 | 심함 |
비교재 G | 13 | 1100 | 0.2 | 없음 | 미세 |
비교재 H | 20 | 400 | 0.3 | 미세 | 없음 |
비교재 I | 15 | 60 | 0.28 | 심함 | 없음 |
비교재 J | 19 | 40 | 0.29 | 심함 | 없음 |
구분 | 냉각수량(L/kg 분) | 분사시간(분) | 공기/냉각수 | 주편 표면온도(oC) | 스케일 두께(mm) |
발명재1 | 100 | 28 | 1.0 | 1100 | 35(균일) |
발명재2 | 110 | 22 | 1.1 | 1160 | 34(균일) |
발명재3 | 120 | 20 | 1.0 | 1156 | 37(균일) |
발명재4 | 100 | 22 | 1.1 | 1121 | 33(균일) |
비교재1 | 50 | 20 | 1.0 | 1111 | 22(불균일) |
비교재2 | 80 | 20 | 1.0 | 1121 | 30(불균일) |
비교재3 | 100 | 20 | 0.5 | 1082 | 10(불균일) |
비교재4 | 100 | 20 | 0.6 | 1198 | 12(불균일) |
비교재5 | 100 | 20 | 0.8 | 1145 | 23(불균일) |
비교재6 | 100 | 15 | 1.0 | 1220 | 22(불균일) |
비교재7 | 100 | 10 | 1.0 | 1230 | 12(불균일) |
비교재8 | 100 | 20 | 1.0 | 932 | 15(불균일) |
비교재9 | 100 | 20 | 1.0 | 1062 | 26(불균일) |
구분 | C | Si | Mn | Cr | Ni | Cu | N | 주조법 | 질소배출 | 내부기공 |
비교예1 | 0.05 | 1.35 | 2.8 | 20.3 | 1.06 | 1.0 | 0.23 | 연속주조 | X | O |
비교예2 | 0.05 | 1.35 | 2.8 | 20.3 | 1.06 | 1.0 | 0.23 | 급속주조 | X | O |
실시예1 | 0.045 | 1.08 | 3.02 | 19.63 | 0.98 | 0.98 | 0.272 | 급속주조 | O | X |
실시예2 | 0.021 | 1.3 | 3.2 | 19.89 | 1.14 | 0.8 | 0.28 | 급속주조 | O | X |
실시예3 | 0.031 | 0.6 | 3.0 | 20.02 | 0.9 | 0.7 | 0.24 | 급속주조 | O | X |
실시예4 | 0.033 | 1.2 | 3.09 | 20.21 | 0.8 | 0.7 | 0.24 | 급속주조 | O | X |
실시예5 | 0.021 | 0.8 | 2.63 | 20.13 | 0.85 | 0.9 | 0.22 | 급속주조 | O | X |
Claims (16)
- 페라이트-오스테나이트계 린 듀플렉스 스테인리스강으로서,하기의 [식 2]로 표현되는 오스테나이트상의 적층결함에너지(SFE) 값이 19 ~ 37이고, 소성 유기 마르텐사이트상이 형성되는 임계 변형 값의 범위가 0.1 ~ 0.25인 린 듀플렉스 스테인리스강.SFE = 25.7+1.59×Ni/[K(Ni)-K(Ni)×V(γ)+V(γ)]+0.795×Cu/[K(Cu)-K(Cu)×V(γ)+V(γ)]-0.85×Cr/[K(Cr)-K(Cr)×V(γ)+V(γ)]+0.001×(Cr/[K(Cr)-K(Cr)×V(γ)+V(γ)])2+38.2×(N/[K(N)-K(N)×V(γ)+V(γ)])0.5-2.8×Si/[K(Si)-K(Si)×V(γ)+V(γ)]-1.34×Mn/[K(Mn)-K(Mn)×V(γ)+V(γ)]+0.06×(Mn/[K(Mn)-K(Mn)×V(γ)+V(γ)])2 ……………… [식 2][식 2]에서 Ni, Cu, Cr, N, Si, Mn은 각 성분원소의 전체 함량(wt%)을 의미하고, K(x)는 각 성분원소(x)의 분배계수로서, 하기의 [식 3]로 표현되며, V(γ)는 오스테나이트 상분율(0.45 ~ 0.75 범위) 임.K(x) = [페라이트상에 있는 x원소의 함량]/[오스테나이트상에 있는 x원소의 함량] ……………… [식 3]
- 청구항 1에 있어서,상기 K(x) 중 K(Cr)=1.16, K(Ni)=0.57, K(Mn)=0.73, K(Cu)=0.64이고,K(N)과 K(Si)는 N과 Si의 함량(wt%)에 따라 하기의 값인 린 듀플렉스 스테인리스강.N: 0.2 ~ 0.32% 인 경우 K(N) = 0.15,N < 0.2% 인 경우 K(N) = 0.25,Si ≤ 1.5% 인 경우 K(Si) = 2.76-0.96×Si,Si > 1.5% 인 경우 K(Si) = 1.4
- 청구항 1 또는 청구항 2에 있어서,상기 스테인리스강의 연신율은 45% 이상인 린 듀플렉스 스테인리스강.
- 청구항 1에 있어서,상기 스테인리스강은 중량%로, C: 0.08% 이하(O% 제외), Si: 0.2 ~ 3.0%, Mn: 2 ~ 4%, Cr: 18 ~ 24%, Ni: 0.2 ~ 2.5%, N: 0.15 ~ 0.32%, Cu: 0.2 ~ 2.5%, 잔부 Fe 및 기타 불가피한 불순물을 포함하는 린 듀플렉스 스테인리스강.
- 청구항 4에 있어서,상기 스테인리스강은 중량%로, W: 0.1 ~ 1.0% 및 Mo: 0.1 ~ 1.0% 중 적어도 1종 이상을 더 포함하는 린 듀플렉스 스테인리스강.
- 청구항 4에 있어서,상기 스테인리스강은 중량%로, Ti: 0.001 ~ 0.1%, Nb: 0.001 ~ 0.05% 및 V: 0.001 ~ 0.15% 중 적어도 1종 이상을 더 포함하는 린 듀플렉스 스테인리스강의 제조방법.
- 페라이트-오스테나이트계 린 듀플렉스 스테인리스강을 제조하는 방법으로서,용강을 준비하는 과정과;하기의 [식 2]로 표현되는 오스테나이트상의 적층결함에너지(SFE) 값이 19 ~ 37이고, 소성 유기 마르텐사이트상이 형성되는 임계 변형 값의 범위가 0.1 ~ 0.25가 되도록 상기 용강을 스테인리스강으로 처리하는 과정을 포함하는 린 듀플렉스 스테인리스강의 제조방법.SFE = 25.7+1.59×Ni/[K(Ni)-K(Ni)×V(γ)+V(γ)]+0.795×Cu/[K(Cu)-K(Cu)×V(γ)+V(γ)]-0.85×Cr/[K(Cr)-K(Cr)×V(γ)+V(γ)]+0.001×(Cr/[K(Cr)-K(Cr)×V(γ)+V(γ)])2+38.2×(N/[K(N)-K(N)×V(γ)+V(γ)])0.5-2.8×Si/[K(Si)-K(Si)×V(γ)+V(γ)]-1.34×Mn/[K(Mn)-K(Mn)×V(γ)+V(γ)]+0.06×(Mn/[K(Mn)-K(Mn)×V(γ)+V(γ)])2 ……………… [식 2][식 2]에서 Ni, Cu, Cr, N, Si, Mn은 각 성분원소의 전체 함량(wt%)을 의미하고, K(x)는 각 성분원소(x)의 분배계수로서, 하기의 [식 3]로 표현되며, V(γ)는 오스테나이트 상분율(0.45 ~ 0.75 범위) 임.K(x) = [페라이트상에 있는 x원소의 함량]/[오스테나이트상에 있는 x원소의 함량] ……………… [식 3]
- 청구항 7에 있어서,상기 용강을 스테인리스강으로 처리하는 과정은,상기 용강을 이론 응고온도보다 10 ~ 50℃ 높게 유지하면서 턴디쉬에 임시저장하는 단계와;상기 턴디쉬에서 용강을 주형으로 주입하여 500 ~ 1500℃/min의 냉각속도를 유지하면서 주형을 통과시켜 1차 냉각하는 단계와;1차 냉각되어 응고쉘이 형성된 용강을 세그먼트로 인발하여 통과시키면서 2차 냉각하는 단계를 포함하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 8에 있어서,상기 2차 냉각하는 단계에서 응고쉘이 형성된 용강으로 0.25 ~ 0.35ℓ/㎏의 냉각수를 분사하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 8에 있어서,상기 2차 냉각하는 단계 이후에 인발되는 주편의 표면온도가 1100 ~ 1200℃인 범위에서 주편의 표면으로 100 ~ 125ℓ/㎏·분의 냉각수를 공기와 냉각수의 비율(공기/냉각수)이 1.0 ~ 1.2가 되도록 혼합하여 분사하여 3차 냉각하는 단계를 더 포함하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 7에 있어서,상기 용강을 스테인리스강으로 처리하는 과정은,상기 용강을 한 쌍의 주조롤 사이를 통과시키면서 응고시켜 스트립을 제조하는 단계를 포함하되,상기 스트립을 제조하는 단계에서 용강 중에 포함된 질소 고용 한도 이상의 질소는 상기 주조롤을 통하여 응고쉘 외부로 배출시키는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 11에 있어서,상기 스트립을 제조하는 단계에서는 외주면에 원주 방향으로 가스 배출채널이 형성된 주조롤을 상기 한 쌍의 주조롤 중 적어도 어느 하나로 사용하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 12에 있어서,상기 스트립을 제조하는 단계에서 사용되는 주조롤에 형성된 가스 배출채널은 폭 50 ~ 500㎛, 깊이 50 ~ 300㎛로 복수 개가 형성되며, 서로 이웃하는 가스 배출채널 사이의 간격은 100 ~ 1000㎛이고, 상기 주조롤의 표면에는 15 ~ 25㎛이 요철이 형성된 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 7에 있어서,상기 용강을 준비하는 과정에서 상기 용강은 중량%로, C: 0.08% 이하(O% 제외), Si: 0.2 ~ 3.0%, Mn: 2 ~ 4%, Cr: 18 ~ 24%, Ni: 0.2 ~ 2.5%, N: 0.15 ~ 0.32%, Cu: 0.2 ~ 2.5%, 잔부 Fe 및 기타 불가피한 불순물을 포함하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 14에 있어서,상기 용강을 준비하는 과정에서 상기 용강은 중량%로 W: 0.1 ~ 1.0% 및 Mo: 0.1 ~ 1.0% 중 적어도 1종 이상을 더 포함하는 린 듀플렉스 스테인리스강의 제조방법.
- 청구항 14에 있어서,상기 용강을 준비하는 과정에서 상기 용강은 중량%로, Ti: 0.001 ~ 0.1%, Nb: 0.001 ~ 0.05% 및 V: 0.001 ~ 0.15% 중 적어도 1종 이상을 더 포함하는 린 듀플렉스 스테인리스강의 제조방법.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP15873672.8A EP3239344B1 (en) | 2014-12-26 | 2015-12-24 | Method for producing a lean duplex stainless steel |
CN201580071241.8A CN107107173B (zh) | 2014-12-26 | 2015-12-24 | 经济型双相不锈钢及其制造方法 |
US15/536,391 US20170326628A1 (en) | 2014-12-26 | 2015-12-24 | Lean duplex stainless steel and method for producing the same |
JP2017530070A JP6484716B2 (ja) | 2014-12-26 | 2015-12-24 | リーン二相系ステンレス鋼及びその製造方法 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR10-2014-0191170 | 2014-12-26 | ||
KR20140191170 | 2014-12-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016105145A1 true WO2016105145A1 (ko) | 2016-06-30 |
Family
ID=56151068
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/KR2015/014235 WO2016105145A1 (ko) | 2014-12-26 | 2015-12-24 | 린 듀플렉스 스테인리스강 및 그 제조방법 |
Country Status (6)
Country | Link |
---|---|
US (1) | US20170326628A1 (ko) |
EP (1) | EP3239344B1 (ko) |
JP (1) | JP6484716B2 (ko) |
KR (1) | KR101766550B1 (ko) |
CN (1) | CN107107173B (ko) |
WO (1) | WO2016105145A1 (ko) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101795406B1 (ko) | 2016-06-27 | 2017-11-08 | 현대자동차 주식회사 | 마모 보상장치, 이를 구비한 클러치 액추에이터 유닛, 및 이를 구비한 차량 |
PL3301197T3 (pl) * | 2016-09-29 | 2022-02-21 | Outokumpu Oyj | Sposób odkształcania na zimno stali austenitycznej |
KR101977492B1 (ko) * | 2017-11-10 | 2019-08-28 | 주식회사 포스코 | 고질소 오스테나이트계 스테인리스 강 및 그 제조방법 |
KR102020405B1 (ko) * | 2017-12-15 | 2019-09-10 | 주식회사 포스코 | 표면품질이 우수한 고질소 스테인리스강 및 이의 제조방법 |
CN108570629B (zh) * | 2018-04-27 | 2020-03-20 | 钢铁研究总院 | 一种高强、耐酸腐蚀的双相不锈钢及其制备方法 |
CN108796385A (zh) * | 2018-06-15 | 2018-11-13 | 酒泉钢铁(集团)有限责任公司 | 一种含钛耐蚀耐磨低成本打壳锤头材料及使用该材料制备锤头的方法 |
CN110369686A (zh) * | 2019-07-03 | 2019-10-25 | 西安理工大学 | 一种铸铁水平连铸三次喷冷装置 |
CN114619007B (zh) * | 2022-02-14 | 2024-03-08 | 包头钢铁(集团)有限责任公司 | 一种低合金高氮钢连铸坯的生产方法 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005154890A (ja) * | 2003-11-07 | 2005-06-16 | Nippon Steel & Sumikin Stainless Steel Corp | 加工性に優れたオ−ステナイト系高Mnステンレス鋼 |
JP2010196103A (ja) * | 2009-02-24 | 2010-09-09 | Nisshin Steel Co Ltd | Ni節減型ステンレス鋼製自動車用部材 |
KR20140052079A (ko) * | 2011-09-07 | 2014-05-02 | 오또꿈뿌 오와이제이 | 듀플렉스 스테인레스 강 |
KR20140080347A (ko) * | 2012-12-20 | 2014-06-30 | 주식회사 포스코 | 고연성 린 듀플렉스 스테인리스강. |
KR20140082491A (ko) * | 2012-12-24 | 2014-07-02 | 주식회사 포스코 | 듀플렉스강의 냉간압연 방법 |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07138704A (ja) | 1993-11-12 | 1995-05-30 | Nisshin Steel Co Ltd | 高強度高延性複相組織ステンレス鋼およびその製造方法 |
EP0755737B2 (en) * | 1995-02-09 | 2013-08-07 | JFE Steel Corporation | Continuous casting method for austenitic stainless steel |
JPH10257018A (ja) | 1997-03-07 | 1998-09-25 | Sharp Corp | 同期回路 |
KR20010073236A (ko) * | 1999-11-09 | 2001-08-01 | 이구택 | 텅스텐 함유 듀플렉스 스테인레스강 연속주조방법 |
JP4760031B2 (ja) * | 2004-01-29 | 2011-08-31 | Jfeスチール株式会社 | 成形性に優れるオーステナイト・フェライト系ステンレス鋼 |
EP1715073B1 (en) * | 2004-01-29 | 2014-10-22 | JFE Steel Corporation | Austenitic-ferritic stainless steel |
JP2005271307A (ja) | 2004-03-23 | 2005-10-06 | Konica Minolta Business Technologies Inc | 画像形成装置および画像形成装置の装置情報出力方法 |
KR100821059B1 (ko) * | 2006-12-28 | 2008-04-16 | 주식회사 포스코 | 내식성 및 장출성형성이 우수한 페라이트계 스테인리스강및 그 제조방법 |
CN101765671B (zh) * | 2007-08-02 | 2012-01-11 | 新日铁住金不锈钢株式会社 | 耐蚀性和加工性优良的铁素体-奥氏体系不锈钢及其制造方法 |
JP5388589B2 (ja) * | 2008-01-22 | 2014-01-15 | 新日鐵住金ステンレス株式会社 | 加工性と衝撃吸収特性に優れた構造部材用フェライト・オーステナイト系ステンレス鋼板およびその製造方法 |
CN101812647B (zh) * | 2009-02-25 | 2012-10-10 | 宝山钢铁股份有限公司 | 一种双相不锈钢及其制造方法 |
FI122657B (fi) * | 2010-04-29 | 2012-05-15 | Outokumpu Oy | Menetelmä korkean muokattavuuden omaavan ferriittis-austeniittisen ruostumattoman teräksen valmistamiseksi ja hyödyntämiseksi |
KR20120132691A (ko) * | 2010-04-29 | 2012-12-07 | 오또꿈뿌 오와이제이 | 높은 성형성을 구비하는 페라이트-오스테나이트계 스테인리스 강의 제조 및 사용 방법 |
KR20120016369A (ko) * | 2010-08-16 | 2012-02-24 | 주식회사 포스코 | 연속박판 주조기를 이용한 듀플렉스 스테인레스 강의 제조방법 |
KR101379079B1 (ko) * | 2011-11-30 | 2014-03-28 | 주식회사 포스코 | 린 듀플렉스 스테인리스강 |
WO2013081422A1 (ko) * | 2011-11-30 | 2013-06-06 | (주)포스코 | 린 듀플렉스 스테인리스강 및 그 제조방법 |
CN102634740A (zh) * | 2012-04-27 | 2012-08-15 | 宝山钢铁股份有限公司 | 一种高塑性的经济型双相不锈钢及其制造方法 |
KR101372692B1 (ko) * | 2012-05-08 | 2014-03-10 | 주식회사 포스코 | 고질소 스테인레스 강판을 제조하기 위한 박판주조롤 및 이를 이용한 고질소 스테인레스 강판의 제조방법 |
KR20140084721A (ko) * | 2012-12-27 | 2014-07-07 | 주식회사 포스코 | 쌍롤식 박판 주조기 |
CN103602914A (zh) * | 2013-11-15 | 2014-02-26 | 上海大学兴化特种不锈钢研究院 | 一种组织稳定的经济型高性能双相不锈钢 |
KR101613839B1 (ko) | 2013-11-27 | 2016-04-20 | 주식회사 에이치씨바이오텍 | 상황버섯 아임계 추출물이 첨가된 고추장 및 그 제조방법 |
CN104131237A (zh) * | 2014-06-19 | 2014-11-05 | 宝钢不锈钢有限公司 | 具有优良韧性与焊接性的经济型双相不锈钢及其制造方法 |
-
2015
- 2015-12-24 KR KR1020150185726A patent/KR101766550B1/ko active IP Right Grant
- 2015-12-24 JP JP2017530070A patent/JP6484716B2/ja active Active
- 2015-12-24 WO PCT/KR2015/014235 patent/WO2016105145A1/ko active Application Filing
- 2015-12-24 CN CN201580071241.8A patent/CN107107173B/zh active Active
- 2015-12-24 US US15/536,391 patent/US20170326628A1/en not_active Abandoned
- 2015-12-24 EP EP15873672.8A patent/EP3239344B1/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005154890A (ja) * | 2003-11-07 | 2005-06-16 | Nippon Steel & Sumikin Stainless Steel Corp | 加工性に優れたオ−ステナイト系高Mnステンレス鋼 |
JP2010196103A (ja) * | 2009-02-24 | 2010-09-09 | Nisshin Steel Co Ltd | Ni節減型ステンレス鋼製自動車用部材 |
KR20140052079A (ko) * | 2011-09-07 | 2014-05-02 | 오또꿈뿌 오와이제이 | 듀플렉스 스테인레스 강 |
KR20140080347A (ko) * | 2012-12-20 | 2014-06-30 | 주식회사 포스코 | 고연성 린 듀플렉스 스테인리스강. |
KR20140082491A (ko) * | 2012-12-24 | 2014-07-02 | 주식회사 포스코 | 듀플렉스강의 냉간압연 방법 |
Also Published As
Publication number | Publication date |
---|---|
EP3239344B1 (en) | 2021-10-20 |
EP3239344A4 (en) | 2018-05-30 |
CN107107173B (zh) | 2019-11-01 |
JP6484716B2 (ja) | 2019-03-13 |
KR20160080275A (ko) | 2016-07-07 |
CN107107173A (zh) | 2017-08-29 |
JP2018503741A (ja) | 2018-02-08 |
EP3239344A1 (en) | 2017-11-01 |
KR101766550B1 (ko) | 2017-08-10 |
US20170326628A1 (en) | 2017-11-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2016105145A1 (ko) | 린 듀플렉스 스테인리스강 및 그 제조방법 | |
WO2016098964A1 (ko) | 재질 불균일이 작고 성형성이 우수한 고강도 냉연강판, 용융아연도금강판, 및 그 제조 방법 | |
WO2016104975A1 (ko) | Pwht 후 인성이 우수한 고강도 압력용기용 강재 및 그 제조방법 | |
WO2013081422A1 (ko) | 린 듀플렉스 스테인리스강 및 그 제조방법 | |
WO2015099373A1 (ko) | 용접열영향부 인성이 우수한 초고강도 용접구조용 강재 및 이의 제조방법 | |
WO2012002638A2 (ko) | 초고강도 철근 및 그 제조방법 | |
WO2015023012A1 (ko) | 초고강도 강판 및 그 제조방법 | |
WO2014014246A1 (ko) | 마르텐사이트계 스테인리스강 및 그 제조방법 | |
WO2018030790A1 (ko) | 재질편차가 적고 표면품질이 우수한 고강도 열연강판 및 그 제조방법 | |
WO2010016702A9 (ko) | 친환경 무연쾌삭강 및 그 제조방법 | |
WO2017171366A1 (ko) | 항복강도와 연성이 우수한 고강도 냉연강판, 도금강판 및 이들의 제조방법 | |
WO2019132426A1 (ko) | 자기적 특성 및 형상이 우수한 박물 무방향성 전기강판 및 그 제조방법 | |
WO2019231023A1 (ko) | Twb 용접 특성이 우수한 열간성형용 al-fe 합금화 도금강판, 열간성형 부재 및 그들의 제조방법 | |
WO2019009675A1 (ko) | 재질편차가 적고 표면품질이 우수한 초고강도 열연강판 및 그 제조방법 | |
WO2017105025A1 (ko) | 화성처리성 및 굽힘가공성이 우수한 초고강도 강판 및 이의 제조방법 | |
WO2018117497A1 (ko) | 길이방향 균일 연신율이 우수한 용접강관용 강재, 이의 제조방법 및 이를 이용한 강관 | |
WO2020111702A1 (ko) | 내구성이 우수한 고강도 강재 및 이의 제조방법 | |
WO2018117523A1 (ko) | 고온연신 특성이 우수한 고강도 강판, 온간프레스 성형부재 및 이들의 제조방법 | |
WO2015099459A1 (ko) | 성형성 및 내리징성이 향상된 페라이트계 스테인리스강 및 그 제조방법 | |
WO2018117507A1 (ko) | 저온인성이 우수한 저항복비 강판 및 그 제조방법 | |
WO2018117470A1 (ko) | 저온역 버링성이 우수한 고강도 강판 및 이의 제조방법 | |
WO2019132262A1 (ko) | 피로균열 전파 억제 특성이 우수한 구조용 고강도 강재 및 그 제조방법 | |
WO2019132420A1 (ko) | 자기적 특성 및 형상이 우수한 박물 무방향성 전기강판 및 그 제조방법 | |
WO2020111856A2 (ko) | 연성 및 저온 인성이 우수한 고강도 강재 및 이의 제조방법 | |
WO2019124809A1 (ko) | 취성균열 전파 저항성이 우수한 구조용 강재 및 그 제조방법 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 15873672 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2017530070 Country of ref document: JP Kind code of ref document: A |
|
REEP | Request for entry into the european phase |
Ref document number: 2015873672 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 15536391 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |