WO2015174078A1 - フェライト系ステンレス鋼 - Google Patents
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- WO2015174078A1 WO2015174078A1 PCT/JP2015/002406 JP2015002406W WO2015174078A1 WO 2015174078 A1 WO2015174078 A1 WO 2015174078A1 JP 2015002406 W JP2015002406 W JP 2015002406W WO 2015174078 A1 WO2015174078 A1 WO 2015174078A1
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- 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
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- 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
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- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- 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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- 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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- 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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- 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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- 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
- C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
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- 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
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- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
Definitions
- the present invention relates to a ferritic stainless steel having excellent thermal fatigue properties, high temperature fatigue properties and oxidation resistance.
- the ferritic stainless steel of the present invention is preferably applicable to exhaust system members used in high temperature environments such as exhaust pipes of automobiles and motorcycles, catalyst outer cylinder materials (also referred to as converter cases) and exhaust ducts of thermal power plants. is there.
- Exhaust system members such as exhaust manifolds, exhaust pipes, converter cases, and mufflers used in automobile exhaust system environments have thermal fatigue characteristics, high-temperature fatigue characteristics, and oxidation resistance (hereinafter collectively referred to as "heat resistance”). It may be called.)
- heat resistance oxidation resistance
- steels containing Nb and Si for example, JFE429EX (15 mass% Cr-0.9 mass% Si-0.4 mass% Nb system) (hereinafter referred to as Nb-) are used.
- a Cr-containing steel such as Si is sometimes used.
- Cr-containing steel containing Nb has excellent heat resistance.
- the raw material cost of Nb itself is high, resulting in an increase in the manufacturing cost of steel. Therefore, from the viewpoint of manufacturing cost, it is necessary to develop steel having high heat resistance while minimizing the addition of Nb.
- Patent Document 1 discloses a stainless steel plate having improved heat resistance by adding Ti, Cu and B in combination.
- Patent Document 2 discloses a stainless steel plate with improved workability by adding Cu.
- Patent Document 3 discloses a heat-resistant ferritic stainless steel sheet that is improved in heat resistance by adding Ti.
- Patent Document 4 discloses a heat-resistant ferritic stainless steel sheet having improved heat resistance by adding Nb, Cu, Ti, Ni, and Al.
- oxidation resistance when referred to as oxidation resistance, it means both continuous oxidation resistance and repeated oxidation resistance.
- Patent Document 3 does not disclose an example in which Cu, Ti, Ni and B are added in combination. If B is not added, there is a problem that the effect of refining when ⁇ -Cu is precipitated cannot be obtained, and excellent thermal fatigue characteristics cannot be obtained.
- the present invention was completed in order to solve the above problems, and an object thereof is to provide a ferritic stainless steel having excellent thermal fatigue characteristics and oxidation resistance, and extremely excellent high temperature fatigue characteristics. .
- Patent Document 4 does not describe the O content in steel.
- a ferritic stainless steel sheet having excellent thermal fatigue characteristics and excellent high temperature fatigue characteristics is obtained by limiting the O content to an appropriate amount in consideration of the influence of the O content in the steel. Can be provided.
- excellent thermal fatigue characteristics means that the life when repeating between 800 ° C. and 100 ° C. with a constraint factor of 0.5 is 910 cycles or more.
- excellent oxidation resistance means that the increase in oxidation after being kept at 1000 ° C. in the atmosphere for 300 hours is less than 50 g / m 2 and increases between 1000 ° C. and 100 ° C. in the atmosphere. Oxidation scale peeling does not occur after 400 cycles of temperature and temperature drop.
- excellent high temperature fatigue properties as used in the present invention means that no fracture occurs even when a bending stress of 70 MPa is repeatedly applied 100 ⁇ 10 5 times at 800 ° C.
- the present invention has been made by further studying the above knowledge, and the gist thereof is as follows.
- C 0.020% or less
- Si 3.0% or less
- Mn 2.0% or less
- P 0.040% or less
- S 0.030% or less
- Cr 10 0.0-20.0%
- N 0.020% or less
- Nb 0.005-0.15%
- Al 0.20-3.0%
- Cu 0.55 to 1.60%
- B 0.0002 to 0.0050%
- Ni 0.05 to 1.0%
- O 0.0030% or less
- ferritic stainless steel characterized in that the balance consists of Fe and inevitable impurities.
- C and N in 5 ⁇ (C + N) and Al and O in Al / O represent the content (% by mass) of each element.
- [3] Furthermore, it contains one or more selected from Ca: 0.0005 to 0.0030% and Mg: 0.0010 to 0.0030% by mass% [1] or [1] 2] ferritic stainless steel.
- the ferritic stainless steel of the present invention has excellent thermal fatigue characteristics, oxidation resistance, and extremely high temperature fatigue characteristics, it is particularly preferable as an exhaust system member for automobiles.
- FIG. 1 is a diagram illustrating a fatigue test piece subjected to a high temperature fatigue test.
- FIG. 2 is a diagram for explaining a thermal fatigue test piece.
- FIG. 3 is a diagram showing thermal fatigue test conditions (temperature, restraint conditions).
- FIG. 4 is a diagram for explaining the influence of the Al content and the O content on the high temperature fatigue test characteristics.
- C 0.020% or less
- C is an element effective for increasing the strength of steel.
- C content shall be 0.020% or less.
- the C content is preferably 0.015% or less. More desirably, it is 0.010% or less.
- the C content is preferably 0.001% or more, and more preferably 0.003% or more.
- Si 3.0% or less Si is an important element for improving oxidation resistance. The effect is easily obtained by making the Si content 0.1% or more. When more excellent oxidation resistance is required, the Si content is desirably 0.3% or more. However, when the Si content exceeds 3.0%, not only the workability of stainless steel is lowered, but also the scale peelability is lowered. Therefore, the Si content is 3.0% or less. A more preferable Si content is in the range of 0.4 to 2.0%, and further preferably in the range of 0.5 to 1.0%.
- Mn 2.0% or less
- Mn is an element that increases the strength of steel and also has an action as a deoxidizer. Moreover, Mn suppresses the oxide scale peeling which becomes easy to produce by containing Si.
- the Mn content is preferably 0.05% or more. However, when the Mn content exceeds 2.0%, not only the increase in oxidation is remarkably increased, but also the ⁇ phase is easily generated at a high temperature and the heat resistance is lowered. Therefore, the Mn content is 2.0% or less.
- a preferable Mn content is in the range of 0.10 to 1.0%. More preferably, it is in the range of 0.15 to 0.50%.
- P 0.040% or less
- P is a harmful element that lowers toughness. It is desirable to reduce the P content as much as possible. Therefore, in the present invention, the P content is 0.040% or less. Preferably, it is 0.030% or less.
- S 0.030% or less
- S is a harmful element that lowers the elongation and r value, adversely affects the formability, and lowers the corrosion resistance, which is a basic characteristic of stainless steel. For this reason, it is desirable to reduce S content as much as possible. Therefore, in the present invention, the S content is 0.030% or less. Preferably, it is 0.010% or less. More preferably, it is 0.005% or less.
- Cr 10.0-20.0% Cr is an important element effective for improving the corrosion resistance and oxidation resistance, which are the characteristics of stainless steel. If the Cr content is less than 10.0%, sufficient oxidation resistance cannot be obtained. On the other hand, Cr is an element that solidifies and strengthens steel at room temperature to make it harder and lower ductility. In particular, when the Cr content exceeds 20.0%, this adverse effect becomes significant, so the upper limit is made 20.0%.
- a preferable Cr content is in the range of 12.0 to 18.0%. More preferably, it is in the range of 14.0 to 16.0%.
- N 0.020% or less
- N is an element that lowers the toughness and formability of steel. If the N content exceeds 0.020%, the moldability is significantly reduced. Therefore, the N content is 0.020% or less. Moreover, it is preferable to reduce N content as much as possible from a viewpoint of ensuring the toughness of a stainless steel, and a moldability, and it is desirable to set it as 0.015% or less. Thus, it is preferable not to add N positively, and stainless steel not positively adding N, that is, stainless steel not containing N and stainless steel containing N as an unavoidable impurity are the stainless steels of the present invention. However, in order to reduce the N content, it is necessary to lengthen the refining time. For this reason, reducing N content excessively leads to an increase in manufacturing cost. In the present invention, the N content is preferably 0.005% or more and 0.015% or less in consideration of the balance of toughness, moldability, and manufacturing cost.
- Nb 0.005 to 0.15%
- the Cu-containing steel as in the present invention has the effect of precipitating ⁇ -Cu more finely, suppressing the coarsening of ⁇ -Cu, and improving thermal fatigue properties and high temperature fatigue properties.
- the effect is acquired by containing Nb content 0.005% or more.
- the recrystallization temperature of the steel must be greatly increased, the annealing temperature during production must be increased, and the production cost will also increase. Therefore, the Nb content is in the range of 0.005 to 0.15%. Preferably, it is in the range of 0.02 to 0.12%, more preferably in the range of 0.04 to 0.10%.
- Al 0.20 to 3.0%
- Al is known as an element that contributes to improving the oxidation resistance and high-temperature salt corrosion resistance of Cu-containing steel.
- Al is also important as an element that increases the high temperature strength of the steel by solid solution strengthening and improves the high temperature fatigue properties. These effects can be obtained by setting the Al content to 0.20% or more.
- the Al content is in the range of 0.20 to 3.0%. Preferably, it is in the range of 0.25 to 1.0%.
- the Al content is in the range of 0.30 to 0.50% so that the high temperature fatigue characteristics, oxidation resistance and toughness are most well balanced.
- Al is an element that is easily combined with O to become an oxide.
- O content in the steel is large, Al forms an oxide correspondingly.
- the amount of Al oxide formed increases, the amount of Al solid solution in the steel decreases and the amount of solid solution strengthening decreases.
- the Al oxide formed in combination with O in the steel is likely to be a starting point of cracks, the high temperature fatigue characteristics are deteriorated. For this reason, in the present invention, in order to dissolve Al in the steel as much as possible, the amount of O in the steel is minimized as described later.
- Ti 5 ⁇ (C + N) to 0.50% Ti, like Nb, fixes C and N, and has the effect of improving the corrosion resistance and formability of stainless steel and the intergranular corrosion resistance of welds.
- the Nb content can be minimized. That is, in the present invention, Ti is an important element for fixing C and N. In order to obtain the effect, the Ti content needs to be 5 ⁇ (C + N)% or more.
- C and N in 5 ⁇ (C + N) represent the content (mass%) of each element. If the Ti content is less than this, C and N cannot be sufficiently fixed, and Cr forms carbonitrides at the grain boundaries.
- the Ti content is in the range of 5 ⁇ (C + N) to 0.50%.
- it is in the range of more than 0.15 to 0.40%. More preferably, it is 0.20 to 0.30% of range.
- Cu 0.55 to 1.60%
- Cu is an extremely effective element for improving thermal fatigue characteristics. This is due to the precipitation strengthening of ⁇ -Cu, and in order to obtain the effect in the Ti-containing steel as in the present invention, the Cu content needs to be 0.55% or more.
- Cu lowers oxidation resistance and workability, and if the Cu content exceeds 1.60%, it causes coarsening of ⁇ -Cu, and on the contrary, thermal fatigue characteristics deteriorate. Therefore, the Cu content is in the range of 0.55 to 1.60%. Preferably it is 0.7 to 1.3% of range. However, a sufficient effect of improving thermal fatigue characteristics cannot be obtained only by containing Cu.
- B 0.0002 to 0.0050%
- B improves workability, particularly secondary workability. Furthermore, B improves the thermal fatigue properties in Cu-containing steels such as the present invention because it has the effect of refining ⁇ -Cu to increase the high-temperature strength and to suppress the coarsening of ⁇ -Cu. It is an important element for the present invention effective in the present invention. If B is not contained, ⁇ -Cu tends to be coarsened, and the effect of improving thermal fatigue properties due to the inclusion of Cu cannot be sufficiently obtained.
- B is an important element having an effect of improving oxidation resistance, particularly oxidation resistance in a water vapor atmosphere. These effects can be obtained by making the B content 0.0002% or more.
- the B content is in the range of 0.0002 to 0.0050%. Preferably it is 0.0005 to 0.0030% of range.
- Ni 0.05 to 1.0%
- Ni is an important element in the present invention.
- Ni is an element that not only improves the toughness of the steel but also improves the oxidation resistance. In order to obtain the effect, the Ni content needs to be 0.05% or more.
- the oxidation resistance lowered by the Cu content and the Ti content cannot be compensated, and sufficient oxidation resistance cannot be obtained.
- Insufficient oxidation resistance results in a decrease in the thickness of the base material due to an increase in the amount of oxidation, and a crack starting point due to separation of the oxide scale, resulting in failure to obtain excellent thermal fatigue characteristics.
- Ni is an expensive element and a strong ⁇ -phase forming element.
- the Ni content is in the range of 0.05 to 1.0%. Preferably, it is in the range of 0.10 to 0.50%, more preferably in the range of 0.15 to 0.30%.
- O is an important element in the Al-containing steel as in the present invention.
- O present in the steel is preferentially combined with Al in the steel when exposed to high temperatures.
- the amount of Al solid solution decrease and the high temperature strength decreases, but the Al oxide coarsely precipitated in the steel becomes the starting point of crack generation in the high temperature fatigue test.
- excellent high temperature fatigue characteristics cannot be obtained.
- the O content contained in the steel is preferably reduced as much as possible, and is limited to 0.0030% or less.
- it is 0.0020% or less. More preferably, it is 0.0015% or less.
- Al / O ⁇ 100 As described above, in the Al-containing steel as in the present invention, it is important to reduce the O content in order to improve the high-temperature fatigue characteristics utilizing the solid solution strengthening of Al. Furthermore, the inventors have also investigated the influence of the content ratio of Al and O on high temperature fatigue properties, and after satisfying Al: 0.20 to 3.0 mass% and O ⁇ 0.0030 mass%. It has been found that extremely high temperature fatigue characteristics can be obtained by satisfying Al / O ⁇ 100. The reason for this is that the Al oxide produced in association with O present in the steel is less dense than the Al oxide associated with O that has entered from the outside air when exposed to high temperatures, so that it is resistant to oxidation. This is considered to be because it is difficult to contribute to the improvement of the temperature, allows further entry of O from the outside air, and promotes the generation of the Al oxide that becomes the starting point of the crack. In addition, Al and O in Al / O represent content of each element.
- Component composition C: 0.010%, Si: 0.8%, Mn: 0.3%, P: 0.030%, S: 0.002%, Cr: 14%, N: 0.010% Nb: 0.1%, Ti: 0.25%, Cu: 0.8%, B: 0.0010%, Ni: 0.20%, and Al and O are 0.2% respectively.
- Steels with various contents varied in the range of -2.0% and 0.001-0.005% were melted in the laboratory to obtain 30 kg steel ingots. The steel ingot was heated to 1170 ° C. and then hot rolled to form a sheet bar having a thickness of 35 mm ⁇ width of 150 mm. The sheet bar was heated to 1050 ° C.
- the hot-rolled annealed plate annealed at 900 to 1050 ° C. and pickled was cold-rolled to a thickness of 2 mm, and finish-annealed at 850 to 1050 ° C. to obtain a cold-rolled annealed plate. This was subjected to the following high temperature fatigue test.
- a high temperature fatigue test piece having a shape as shown in FIG. 1 was produced from the cold-rolled annealed plate obtained as described above, and was subjected to the following high temperature fatigue test.
- O (%) on the horizontal axis means O content
- Al (%) on the vertical axis means Al content
- the above is an essential component of the ferritic stainless steel of the present invention. Further, from the viewpoint of improving heat resistance, one or more selected from REM, Zr, V and Co are selected elements (arbitrary components) in the following ranges. May be added.
- REM 0.005 to 0.08%
- Zr 0.01 to 0.50% REM (rare earth element)
- Zr are both elements that improve oxidation resistance.
- the stainless steel of the present invention contains these elements as necessary.
- the REM content is preferably 0.005% or more and the Zr content is preferably 0.01% or more.
- the REM content exceeds 0.08%
- the steel becomes brittle.
- the Zr content exceeds 0.50%, the Zr intermetallic compound precipitates and the steel becomes brittle. Therefore, when REM is contained, its content is 0.0005 to 0.08% or less, and when Zr is contained, its content is 0.01 to 0.50% or less.
- V 0.01 to 0.50%
- V has the effect of improving oxidation resistance as well as improving high-temperature strength. Moreover, it has the effect of suppressing the coarsening of Ti carbonitride that adversely affects high-temperature fatigue properties and toughness, such as crack initiation when coarsened.
- the V content is preferably 0.01% or more. However, when the V content exceeds 0.50%, coarse V (C, N) is precipitated, and on the contrary, the toughness is lowered. Therefore, when V is contained, the V content is in the range of 0.01 to 0.50%. Preferably, it is 0.03 to 0.40% of range. More preferably, it is in the range of 0.05 to 0.25%.
- Co 0.01 to 0.50%
- Co is an element effective for improving toughness and an element for improving high-temperature strength.
- the Co content is preferably 0.01% or more.
- Co is an expensive element, and the above effect is saturated even if the Co content exceeds 0.50%. Therefore, when it contains Co, the content is made 0.01 to 0.50%. Preferably, it is 0.02 to 0.20% of range.
- one or more selected from Ca and Mg may be contained as selective elements in the following range.
- Ca 0.0005 to 0.0030%
- Ca is an effective component for preventing nozzle clogging due to precipitation of Ti-based inclusions that are likely to occur during continuous casting. The effect appears when the Ca content is 0.0005% or more. However, in order to obtain good surface properties without generating surface defects, the Ca content needs to be 0.0030% or less. Therefore, when Ca is contained, its content is set in the range of 0.0005 to 0.0030%. Preferably it is 0.0005 to 0.0020% of range. More preferably, it is in the range of 0.0005 to 0.0015%.
- Mg is an element that improves the equiaxed crystal ratio of the slab and is effective in improving workability and toughness.
- Mg also has an effect of suppressing the coarsening of Ti carbonitride. The effect is acquired by making Mg content 0.0010% or more.
- the Mg content exceeds 0.0030%, the surface properties of the steel deteriorate. Therefore, when Mg is contained, its content is set in the range of 0.0010 to 0.0030%. Preferably it is 0.0010 to 0.0020% of range. More preferably, it is in the range of 0.0010 to 0.0015%.
- Mo may be contained as a selective element in the following range.
- Mo 0.05 to 1.0% or less
- Mo is an element that improves the heat resistance by significantly increasing the strength of the steel by solid solution strengthening. Mo also has the effect of improving the salt corrosion resistance at high temperatures. The effect is obtained when the Mo content is 0.05% or more.
- Mo is an expensive element, and in the Ti, Cu, Al-containing steel as in the present invention, the oxidation resistance is lowered. Therefore, when Mo is contained, the upper limit of the content is 1.0%. Therefore, when it contains Mo, the content is made 0.05 to 1.0% in range. Preferably, it is 0.10 to 0.50% or less.
- the balance other than the above essential elements and selective elements is Fe and inevitable impurities.
- the method for producing the stainless steel of the present invention is basically not particularly limited as long as it is an ordinary method for producing ferritic stainless steel.
- the production conditions are controlled in the refining process as described later.
- the example of a manufacturing method is shown below.
- steel is produced in a known melting furnace such as a converter or an electric furnace, or further subjected to secondary refining such as ladle refining or vacuum refining to obtain steel having the above-described component composition of the present invention.
- secondary refining such as ladle refining or vacuum refining to obtain steel having the above-described component composition of the present invention.
- the addition of Al may not sufficiently reduce the O content in the steel.
- the steel is made into a slab by a continuous casting method or an ingot-bundling rolling method. Thereafter, the slab is preferably made into a cold-rolled annealed plate through steps such as hot-rolling, hot-rolled sheet annealing, pickling, cold-rolling, finish annealing and pickling in this order.
- the cold rolling may be performed once or two or more cold rolling sandwiching the intermediate annealing, and the steps of cold rolling, finish annealing, and pickling may be repeated.
- the above-mentioned hot-rolled sheet annealing may be omitted, and when the surface of the steel sheet is required to be glossy, a skin pass may be applied after cold rolling or after finish annealing.
- a more preferable production method is a method in which at least one of the hot rolling condition and the cold rolling condition is a specific condition.
- suitable manufacturing conditions will be described.
- molten steel containing essential components and optional components added as necessary be melted in a converter or an electric furnace and then subjected to secondary refining by the VOD method.
- the molten steel can be made into a steel material according to a known production method, it is preferable to use a continuous casting method from the viewpoint of productivity and quality.
- the steel material obtained by continuous casting is heated to 1000 to 1250 ° C., for example, and hot rolled into a desired thickness by hot rolling.
- the thickness of the hot-rolled sheet is not particularly limited, but is preferably about 4 mm or more and 6 mm or less. Of course, it can be processed as other than the plate material.
- the hot-rolled sheet is subjected to continuous annealing at 850 ° C. to 1100 ° C. and then descaled by pickling or the like. Thereby, a hot-rolled sheet product is obtained. If necessary, the scale may be removed by shot blasting before pickling.
- the hot-rolled annealed sheet obtained above is cold-rolled to obtain a cold-rolled sheet.
- the thickness of the cold-rolled annealed plate is not particularly limited, but is preferably approximately 1 mm or more and 3 mm or less.
- two or more cold rollings including intermediate annealing may be performed as necessary for the convenience of production.
- the total rolling reduction of the cold rolling process comprising one or more cold rollings is set to 60% or more, preferably 70% or more.
- the cold-rolled sheet is subjected to continuous annealing (finish annealing) at an annealing temperature of 850 to 1150 ° C., more preferably 850 to 1050 ° C., and then pickling. Thereby, a cold-rolled annealing board is obtained.
- finish annealing continuous annealing
- annealing temperature 850 to 1150 ° C., more preferably 850 to 1050 ° C.
- the welding method for welding these members is not particularly limited, and a normal arc welding method such as MIG (Metal Inert Gas), MAG (Metal Active Gas), TIG (Tungsten Inert Gas), or a spot, Resistance welding methods such as welding and seam welding, and high-frequency resistance welding and high-frequency induction welding such as an electric resistance welding method are applicable.
- MIG Metal Inert Gas
- MAG Metal Active Gas
- TIG Tungsten Inert Gas
- Resistance welding methods such as welding and seam welding
- high-frequency resistance welding and high-frequency induction welding such as an electric resistance welding method are applicable.
- a fatigue test piece having the shape shown in FIG. 1 was produced from the cold-rolled annealed plate obtained as described above, and was subjected to the following high temperature fatigue test.
- a bending stress of 70 MPa was applied to the surface of the cold-rolled annealed plate at 800 ° C. and 1300 rpm with a Schenk fatigue tester. At this time, the number of cycles until the test piece was damaged (number of repetitions of breakage) was evaluated as follows as the high temperature fatigue life.
- (fail) repetition number 15 ⁇ 10 5 times Break at less than
- Thermal fatigue test The remaining 50kg steel ingot divided into two parts was heated to 1170 ° C and then hot rolled into a sheet bar 30mm thick x 150mm wide. After annealing at a temperature of 1030 ° C., it was machined, processed into a thermal fatigue test piece having the shape and dimensions shown in FIG. 2, and subjected to the following thermal fatigue test.
- the thermal fatigue test was performed under the condition that the temperature rise / fall was repeated between 100 ° C. and 800 ° C. while restraining the test piece at a restraint rate of 0.5.
- the holding time at 100 ° C. and 800 ° C. at this time was 2 min.
- the thermal fatigue life is calculated by dividing the load detected at 100 ° C. by the cross-sectional area of the test piece soaking parallel part (see FIG. 2), and the stress is 75 for the initial stress (5th cycle). The number of cycles when the stress was reduced to%.
- the thermal fatigue characteristics were evaluated as “ ⁇ ” (pass) when the cycle was 910 cycles or more and “x” (fail) when the cycle was less than 910 cycles.
- the steel of the present invention is not only suitable for exhaust system members such as automobiles, but also suitably used as exhaust system members for thermal power generation systems and solid oxide fuel cell members that require similar characteristics. be able to.
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Abstract
Description
Cは、鋼の強度を高めるのに有効な元素である。しかし、C含有量が0.020%を超えると、靭性および成形性の低下が顕著となる。よって、本発明では、C含有量を0.020%以下とする。なお、ステンレス鋼の成形性を確保する観点からは、C含有量は低いほど好ましく、成形性の観点からはC含有量を0.015%以下とするのが望ましい。さらに望ましくは0.010%以下である。一方、排気系部材としての強度を確保するには、C含有量を0.001%以上とすることが好ましく、より好ましくは、0.003%以上である。
Siは、耐酸化性向上のために重要な元素である。その効果はSi含有量を0.1%以上にすることで得られやすい。より優れた耐酸化性を必要とする場合、Si含有量を0.3%以上にすることが望ましい。しかし、Si含有量が3.0%を超えると、ステンレス鋼の加工性が低下するだけでなく、スケール剥離性も低下する。よって、Si含有量は3.0%以下とする。より好ましいSi含有量は、0.4~2.0%の範囲である、さらに好ましくは0.5~1.0%の範囲である。
Mnは、鋼の強度を高める元素であり、また、脱酸剤としての作用も有する。また、Mnは、Siを含有することで生じやすくなる酸化スケール剥離を抑制する。これらの効果を得るためには、Mn含有量を0.05%以上にすることが好ましい。しかし、Mn含有量が2.0%を超えると、酸化増量が著しく増加するのみならず、高温でγ相が生成しやすくなり耐熱性が低下する。よって、Mn含有量は2.0%以下とする。好ましいMn含有量は、0.10~1.0%の範囲である。さらに好ましくは0.15~0.50%の範囲である。
Pは、靭性を低下させる有害元素である。P含有量は可能な限り低減するのが望ましい。そこで、本発明では、P含有量は0.040%以下とする。好ましくは、0.030%以下である。
Sは、伸びやr値を低下させて、成形性に悪影響を及ぼすとともに、ステンレス鋼の基本特性である耐食性を低下させる有害元素でもある。このため、S含有量はできるだけ低減するのが望ましい。よって、本発明では、S含有量は0.030%以下とする。好ましくは、0.010%以下である。さらに好ましくは0.005%以下である。
Crは、ステンレス鋼の特徴である耐食性、耐酸化性を向上させるのに有効な重要元素である。Cr含有量が10.0%未満では、十分な耐酸化性が得られない。一方、Crは、室温において鋼を固溶強化し、硬質化、低延性化する元素である。特にCr含有量が20.0%を超えると、この弊害が顕著となるので、上限は20.0%とする。好ましいCr含有量は、12.0~18.0%の範囲である。さらに好ましくは14.0~16.0%の範囲である。
Nは、鋼の靭性および成形性を低下させる元素である。N含有量が0.020%を超えると、成形性の低下が顕著となる。よって、N含有量は0.020%以下とする。また、N含有量は、ステンレス鋼の靭性、成形性を確保する観点からは、できるだけ低減するのが好ましく、0.015%以下とするのが望ましい。このように、Nを積極添加しないことが好ましく、Nを積極添加しないステンレス鋼、即ち、Nを含まないステンレス鋼および不可避不純物としてNを含むステンレス鋼は本発明のステンレス鋼である。ただし、N含有量を低減するためには精錬時間を長くする必要がある。このため、N含有量を過剰に低減することは、製造コスト増加に繋がる。本発明では靭性、成形性と製造コストのバランスを考慮してN含有量は0.005%以上0.015%以下が望ましい。
本発明のようなCu含有鋼では、ε-Cuをより微細に析出させて、ε-Cuの粗大化を抑制して、熱疲労特性や高温疲労特性を向上させる効果がある。その効果はNb含有量を0.005%以上含有することで得られる。しかし、0.15%を超えてNbを含有すると、鋼の再結晶温度が大きく上昇して、製造時の焼鈍温度を上昇させなければならなくなり、製造コストも増加してしまう。よって、Nb含有量は、0.005~0.15%の範囲とする。好ましくは、0.02~0.12%の範囲である、より好ましくは0.04~0.10%の範囲である。
AlはCu含有鋼の耐酸化性および耐高温塩害腐食性の向上に寄与する元素として知られている。本発明では、Alは、固溶強化により鋼の高温強度を増加させて高温疲労特性を向上させる元素としても重要である。これらの効果はAl含有量を0.20%以上にすることで得られる。一方、Al含有量が3.0%を超えると鋼の靭性が著しく低下し、脆性破壊し易くなり、優れた高温疲労特性は得られなくなる。そこで、Al含有量は0.20~3.0%の範囲とする。好ましくは0.25~1.0%の範囲である。高温疲労特性と耐酸化性および靭性が最もバランス良く得られるのは、Al含有量が0.30~0.50%の範囲である。
Tiは、Nbと同様、C、Nを固定して、ステンレス鋼の耐食性や成形性、溶接部の粒界腐食性を向上させる作用を有する。本発明では、TiによりC、Nを固定できるため、Nb含有量を最小限に抑えることができる。つまり、本発明では、Tiは、C、Nを固定するために重要な元素となる。その効果を得るためにはTi含有量を5×(C+N)%以上の含有が必要である。ここで、5×(C+N)中のC、Nは各元素の含有量(質量%)を表す。Ti含有量がこれより少ない場合、C、Nを十分に固定することができず、Crが粒界に炭窒化物を形成する。これにより、粒界近傍にCr量が少ない領域(Cr欠乏層)が生じる鋭敏化現象が発生し、ステンレス鋼の耐酸化性が低下してしまう。また、C、Nに対してTiが不足した分はAlがNと結びつくことになるため、本発明において重要なAlの固溶強化による高温疲労特性向上効果も得られなくなる。一方、Ti含有量が0.50%を超えると鋼の靭性が低下するのみならず、酸化スケールの密着性(=耐繰り返し酸化性)が低下する。したがって、Ti含有量は5×(C+N)~0.50%の範囲とする。好ましくは0.15超~0.40%の範囲である。より好ましくは0.20~0.30%の範囲である。
Cuは、熱疲労特性の向上には非常に有効な元素である。これはε-Cuの析出強化に起因したものであり、本発明のようなTi含有鋼においてその効果を得るためには、Cu含有量を0.55%以上にする必要がある。一方、Cuは耐酸化性と加工性を低下させる上、Cu含有量が1.60%を超えるとε-Cuの粗大化を招き、却って熱疲労特性が低下する。したがって、Cu含有量は0.55~1.60%の範囲とする。好ましくは0.7~1.3%の範囲である。ただし、Cu含有だけでは十分な熱疲労特性向上効果は得られない。前述したように、Nbを微量添加することによりε-Cuを微細化し、ε-Cuの粗大化を抑制するのみならず、後述するように、Bを複合添加することにより、同様にε-Cuを微細化し、ε-Cuの粗大化を抑制して析出強化効果を長時間持続させる必要がある。このようにすることで、熱疲労特性を向上させることができる。
Bは、加工性、特に二次加工性を向上させる。さらに、Bは、本発明のようなCu含有鋼においては、ε-Cuを微細化し高温強度を上昇させ、かつε-Cuの粗大化を抑制する効果も有するため、熱疲労特性を向上させるのに有効な本発明に重要な元素である。Bを含有しないとε-Cuが粗大化しやすく、Cu含有による熱疲労特性向上効果が十分に得られない。また、本発明において、Bは、耐酸化性、特に水蒸気雰囲気中の耐酸化性を向上させる効果も有する重要な元素である。これらの効果はB含有量を0.0002%以上にすることで得ることができる。一方、B含有量が0.0050%を超えると鋼の加工性、靭性が低下する。従って、B含有量は0.0002~0.0050%の範囲とする。好ましくは0.0005~0.0030%の範囲である。
Niは本発明において重要な元素である。Niは鋼の靭性を向上させるのみならず、耐酸化性も向上させる元素である。その効果を得るためには、Ni含有量を0.05%以上にする必要がある。Niを含有しないかまたはNi含有量がこれより少ない場合、Cu含有とTi含有により低下した耐酸化性を補うことが出来ず、十分な耐酸化性が得られない。耐酸化性が不足すると、酸化量が増えることで母材の板厚が減少することや、また、酸化スケールが剥離することで亀裂の起点が生じることから、優れた熱疲労特性が得られなくなる。一方、Niは高価な元素であり、また、強力なγ相形成元素である。Ni含有量が1.0%を超えると高温でγ相を生成し、却って耐酸化性が低下する。よって、Ni含有量は0.05~1.0%の範囲とする。好ましくは、0.10~0.50%の範囲である、より好ましくは0.15~0.30%の範囲である。
Oは本発明のようなAl含有鋼において重要な元素である。鋼中に存在するOは、高温に曝された際に鋼中のAlと優先的に結びつく。この結びつきで、Alの固溶量が減少して高温強度が低下するのみならず、鋼中で粗大に析出したAl酸化物は、高温疲労試験において亀裂発生の起点となる。その結果、優れた高温疲労特性が得られなくなってしまう。Oが鋼中に多く存在すると、それだけ多くのAlと結びついてAlの固溶量が減少してしまうのみならず、外部からOが侵入しやすくなるため、鋼中O含有量以上にAl酸化物を形成しやすくなってしまう。従って、鋼中に含まれるO含有量はなるべく低減するのが好ましく、0.0030%以下に限定する。好ましくは0.0020%以下である。さらに好ましくは0.0015%以下である。
上述したように、本発明のようなAl含有鋼においては、Alの固溶強化を利用した高温疲労特性向上のためにO含有量の低減が重要となる。さらに、発明者らは、高温疲労特性に及ぼすAlとOの含有量比の影響についても精査し、Al:0.20~3.0質量%かつO≦0.0030質量%を満たした上で、Al/O≧100を満たすことによって、極めて優れた高温疲労特性が得られることを見出した。この理由としては、鋼中に存在するOと結びついて生成したAl酸化物は、高温に曝された際に外気から侵入したOと結びついたAl酸化物に比べ緻密性に劣るため、耐酸化性の向上に寄与しにくく、外気からのさらなるOの侵入を許し、亀裂の起点となるAl酸化物の生成を促進してしまうためと考えられる。なお、Al/O中のAlおよびOは各元素の含有量を表す。
以下、鋼の成分組成を規定する成分%は、全て質量%を意味する。
成分組成は、C:0.010%、Si:0.8%、Mn:0.3%、P:0.030%、S:0.002%、Cr:14%、N:0.010%、Nb:0.1%、Ti:0.25%、Cu:0.8%、B:0.0010%、Ni:0.20%、をベースとし、これにAl、Oをそれぞれ0.2~2.0%、0.001~0.005%の範囲で含有量を種々に変化させた鋼を実験室的に溶製して30kg鋼塊とした。鋼塊を1170℃に加熱後、熱間圧延して厚さ35mm×幅150mmのシートバーとした。このシートバーを1050℃に加熱後、熱間圧延して板厚5mmの熱延板とした。その後900~1050℃で熱延板焼鈍し酸洗した熱延焼鈍板を冷間圧延により板厚を2mmとし、850~1050℃で仕上げ焼鈍して冷延焼鈍板とした。これを下記の高温疲労試験に供した。
上記のようにして得た冷延焼鈍板から図1に示すような形状の高温疲労試験片を作製し、下記の高温疲労試験に供した。
○(合格):繰り返し数100×105回で破断無し
△(不合格):繰り返し数15×105回以上100×105回以下で破断
×(不合格):繰り返し数15×105回未満で破断
図4に高温疲労試験の結果を示す。図4から、O量を0.0030%以下、Al量を0.20%以上さらにAl/O≧100とすることにより、極めて優れた高温疲労寿命が得られることがわかる。なお、横軸のO(%)はO含有量を意味し、縦軸のAl(%)はAl含有量を意味する。
REM(希土類元素)およびZrはいずれも、耐酸化性を改善する元素である。本発明のステンレス鋼は、これらの元素を必要に応じて含有する。上記効果を得るためには、REM含有量は0.005%以上、Zr含有量は0.01%以上が好ましい。しかし、REM含有量が0.08%を超えると、鋼が脆化する。また、Zr含有量が0.50%を超えると、Zr金属間化合物が析出して、鋼が脆化する。よって、REMを含有する場合、その含有量は0.0005~0.08%以下、Zrを含有する場合、その含有量は0.01~0.50%以下とする。
Vは、高温強度を向上させるのみならず耐酸化性を向上させる効果を有する。また、粗大化すると亀裂の起点になる等、高温疲労特性や靭性に悪影響を及ぼすTi炭窒化物の粗大化を抑制する効果も有する。それらの効果を得るためには、V含有量を0.01%以上にすることが好ましい。しかし、V含有量が0.50%を超えと、粗大なV(C,N)を析出し、却って靭性が低下する。よって、Vを含有する場合、V含有量は0.01~0.50%の範囲とする。好ましくは、0.03~0.40%の範囲である。より好ましくは0.05~0.25%の範囲である。
Coは、靭性の向上に有効な元素であるとともに、高温強度を向上させる元素である。その効果を得るためには、Co含有量を0.01%以上にすることが好ましい。しかし、Coは、高価な元素であり、また、Co含有量が0.50%を超えても、上記効果は飽和する。よって、Coを含有する場合、その含有量は0.01~0.50%の範囲とする。好ましくは、0.02~0.20%の範囲である。
Caは、連続鋳造の際に発生しやすいTi系介在物析出によるノズルの閉塞を防止するのに有効な成分である。Ca含有量が0.0005%以上でその効果は現れる。しかし、表面欠陥を発生させず良好な表面性状を得るためにはCa含有量を0.0030%以下とする必要がある。したがって、Caを含有する場合、その含有量は0.0005~0.0030%の範囲とする。好ましくは0.0005~0.0020%の範囲である。より好ましくは0.0005~0.0015%の範囲である。
Mgはスラブの等軸晶率を向上させ、加工性や靭性の向上に有効な元素である。本発明のようなTi含有鋼においては、Mgは、Tiの炭窒化物の粗大化を抑制する効果も有する。その効果はMg含有量を0.0010%以上にすることで得られる。Ti炭窒化物が粗大化すると、脆性割れの起点が生じ、鋼の靭性が大きく低下する。一方で、Mg含有量が0.0030%を超えると、鋼の表面性状が悪化する。したがって、Mgを含有する場合、その含有量は0.0010~0.0030%の範囲とする。好ましくは0.0010~0.0020%の範囲である。より好ましくは0.0010~0.0015%の範囲である。
Moは、固溶強化により鋼の強度を著しく増加させることで耐熱性を向上させる元素である。Moは高温での耐塩害腐食性を向上させる効果も有する。その効果はMo含有量が0.05%以上で得られる。しかしMoは高価な元素である上、本発明のようなTi、Cu、Al含有鋼においては、耐酸化性を低下させてしまう。そこで、Moを含有する場合、その含有量の上限は1.0%とする。したがって、Moを含有する場合、その含有量は0.05~1.0%の範囲とする。好ましくは0.10~0.50%以下である。
上記のようにして得た冷延焼鈍板から図1に示すような形状の疲労試験片を作製し、下記の高温疲労試験に供した。
○(合格):繰り返し数100×105回で破断無し
△(不合格):繰り返し数15×105回以上100×105回以下で破断
×(不合格):繰り返し数15×105回未満で破断
上記のようにして得た各種冷延焼鈍板から30mm×20mmのサンプルを切り出し、サンプル上部に4mmφの穴をあけ、表面および端面を#320のエメリー紙で研磨し、脱脂後、1000℃に加熱保持した大気雰囲気の炉内にサンプルを吊り下げて、300時間保持した。試験後、サンプルの質量を測定し、予め測定しておいた試験前の質量との差を求め、酸化増量(g/m2)を算出した。なお、試験は各2回実施し、2回とも50g/m2未満の場合を「○」(合格)、1度でも酸化増量が50g/m2以上となった場合は「×」(不合格)、として耐酸化性を評価した。
上記の大気中連続酸化試験と同様の試験片を用いて、大気中において、100℃×1minと1000℃×20minの温度に加熱・冷却を繰り返す熱処理を400サイクル行い、試験前後の試験片の質量差を測定し、単位面積当たりの酸化増量(g/m2)を算出するとともに、試験片表面から剥離したスケールの有無を確認した。スケール剥離が見られた場合は不合格(表1中の「×」)、スケール剥離が見られなかった場合は合格(表1中の「○」)とした。なお、上記試験における加熱速度および、冷却速度は、それぞれ5℃/sec、1.5℃/secとした。
二分割した上記50kg鋼塊の残りの鋼塊を、1170℃に加熱後、熱間圧延して厚さ30mm×幅150mmのシートバーとした後、このシートバーを鍛造し、35mm角の各棒とし、1030℃の温度で焼鈍後、機械加工し、図2に示した形状、寸法の熱疲労試験片に加工し、下記の熱疲労試験に供した。
Claims (4)
- 質量%で、C:0.020%以下、Si:3.0%以下、Mn:2.0%以下、P:0.040%以下、S:0.030%以下、Cr:10.0~20.0%、N:0.020%以下、Nb:0.005~0.15%、Al:0.20~3.0%、Ti:5×(C+N)~0.50%、Cu:0.55~1.60%、B:0.0002~0.0050%、Ni:0.05~1.0%およびO:0.0030%以下を含有し、Al/O≧100を満たして残部がFeおよび不可避的不純物からなることを特徴とするフェライト系ステンレス鋼。
ここで、5×(C+N)中のC、NおよびAl/O中のAl、Oは各元素の含有量(質量%)を表す。 - さらに、質量%で、REM:0.005~0.08%、Zr:0.01~0.50%、V:0.01~0.50%およびCo:0.01~0.50%の中から選ばれる1種以上を含有することを特徴とする請求項1に記載のフェライト系ステンレス鋼。
- さらに、質量%でCa:0.0005~0.0030%およびMg:0.0010~0.0030%の中から選ばれる1種以上を含有することを特徴とする請求項1または2に記載のフェライト系ステンレス鋼。
- さらに、質量%でMo:0.05~1.0%以下を含有することを特徴とする請求項1~3のいずれか1項に記載のフェライト系ステンレス鋼。
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017172027A (ja) * | 2016-03-25 | 2017-09-28 | 新日鐵住金ステンレス株式会社 | Al含有フェライト系ステンレス鋼およびその製造方法 |
WO2018181257A1 (ja) * | 2017-03-30 | 2018-10-04 | 新日鐵住金ステンレス株式会社 | 低比重フェライト系ステンレス鋼板およびその製造方法 |
JP2020147791A (ja) * | 2019-03-13 | 2020-09-17 | 日鉄ステンレス株式会社 | 耐熱フェライト系ステンレス鋼板 |
JP7475205B2 (ja) | 2020-06-10 | 2024-04-26 | 日鉄ステンレス株式会社 | フェライト系ステンレス鋼板、フェライト系ステンレス鋼板の製造方法および自動車排気系部品 |
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JP7058537B2 (ja) * | 2018-03-30 | 2022-04-22 | 日鉄ステンレス株式会社 | 耐塩害腐食性に優れたフェライト系ステンレス鋼 |
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Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04173939A (ja) * | 1990-11-03 | 1992-06-22 | Sumitomo Metal Ind Ltd | 高温強度および靱性に優れたフェライト系ステンレス鋼 |
JP2006193789A (ja) * | 2005-01-14 | 2006-07-27 | Nisshin Steel Co Ltd | 熱処理強化型高強度フェライト系ステンレス鋼及びその製造方法 |
WO2011096454A1 (ja) * | 2010-02-02 | 2011-08-11 | Jfeスチール株式会社 | 靭性に優れた高耐食性フェライト系ステンレス冷延鋼板およびその製造方法 |
WO2013054524A1 (ja) * | 2011-10-14 | 2013-04-18 | Jfeスチール株式会社 | フェライト系ステンレス鋼 |
JP2013227659A (ja) * | 2012-03-22 | 2013-11-07 | Nippon Steel & Sumikin Stainless Steel Corp | 耐スケール剥離性に優れたフェライト系ステンレス鋼板及びその製造方法 |
WO2014050011A1 (ja) * | 2012-09-25 | 2014-04-03 | Jfeスチール株式会社 | フェライト系ステンレス鋼 |
Family Cites Families (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3224694B2 (ja) | 1994-10-07 | 2001-11-05 | 新日本製鐵株式会社 | 耐銹性と加工性に優れたフェライト系ステンレス鋼板 |
JP3782273B2 (ja) | 1999-12-27 | 2006-06-07 | Jfeスチール株式会社 | 電磁鋼板 |
CN1225566C (zh) * | 2001-07-05 | 2005-11-02 | 日新制钢株式会社 | 用作排放汽车废气的管道构件的铁素体不锈钢 |
JP5000281B2 (ja) | 2006-12-05 | 2012-08-15 | 新日鐵住金ステンレス株式会社 | 加工性に優れた高強度ステンレス鋼板およびその製造方法 |
JP4948998B2 (ja) | 2006-12-07 | 2012-06-06 | 日新製鋼株式会社 | 自動車排ガス流路部材用フェライト系ステンレス鋼および溶接鋼管 |
JP4986975B2 (ja) | 2008-10-24 | 2012-07-25 | 新日鐵住金ステンレス株式会社 | 加工性、耐酸化性に優れたAl含有耐熱フェライト系ステンレス鋼板及びその製造方法 |
JP5546911B2 (ja) * | 2009-03-24 | 2014-07-09 | 新日鐵住金ステンレス株式会社 | 耐熱性と加工性に優れたフェライト系ステンレス鋼板 |
JP4702493B1 (ja) | 2009-08-31 | 2011-06-15 | Jfeスチール株式会社 | 耐熱性に優れるフェライト系ステンレス鋼 |
US9399809B2 (en) * | 2011-02-08 | 2016-07-26 | Nippon Steel & Sumikin Stainless Steel Corporation | Hot rolled ferritic stainless steel sheet, method for producing same, and method for producing ferritic stainless steel sheet |
CN103403205B (zh) | 2011-02-17 | 2015-08-12 | 新日铁住金不锈钢株式会社 | 抗氧化性和高温强度优异的高纯度铁素体系不锈钢板及其制造方法 |
JP5709594B2 (ja) * | 2011-03-14 | 2015-04-30 | 新日鐵住金ステンレス株式会社 | 耐銹性と防眩性に優れた高純度フェライト系ステンレス鋼板 |
JP5703075B2 (ja) | 2011-03-17 | 2015-04-15 | 新日鐵住金ステンレス株式会社 | 耐熱性に優れたフェライト系ステンレス鋼板 |
JP5234214B2 (ja) * | 2011-10-14 | 2013-07-10 | Jfeスチール株式会社 | フェライト系ステンレス鋼 |
EP2787096B1 (en) * | 2011-11-30 | 2016-10-12 | JFE Steel Corporation | Ferritic stainless steel |
JP5867243B2 (ja) * | 2012-03-30 | 2016-02-24 | Jfeスチール株式会社 | 溶接部の耐食性に優れるフェライト系ステンレス鋼 |
WO2014148015A1 (ja) * | 2013-03-19 | 2014-09-25 | Jfeスチール株式会社 | ステンレス鋼板 |
JP2015002406A (ja) * | 2013-06-14 | 2015-01-05 | 株式会社Jvcケンウッド | 液晶表示装置のクロック信号調整回路 |
CN105408511B (zh) * | 2013-07-29 | 2018-09-07 | 杰富意钢铁株式会社 | 焊接部的耐腐蚀性优良的铁素体系不锈钢 |
ES2713154T3 (es) * | 2014-01-08 | 2019-05-20 | Jfe Steel Corp | Acero inoxidable ferrítico y método para producir el mismo |
JP5874864B1 (ja) * | 2014-07-31 | 2016-03-02 | Jfeスチール株式会社 | プラズマ溶接用フェライト系ステンレス鋼板およびその溶接方法 |
CN106574333A (zh) * | 2014-07-31 | 2017-04-19 | 杰富意钢铁株式会社 | 铁素体系不锈钢及其制造方法 |
-
2015
- 2015-05-12 JP JP2015542891A patent/JP5900714B1/ja active Active
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Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04173939A (ja) * | 1990-11-03 | 1992-06-22 | Sumitomo Metal Ind Ltd | 高温強度および靱性に優れたフェライト系ステンレス鋼 |
JP2006193789A (ja) * | 2005-01-14 | 2006-07-27 | Nisshin Steel Co Ltd | 熱処理強化型高強度フェライト系ステンレス鋼及びその製造方法 |
WO2011096454A1 (ja) * | 2010-02-02 | 2011-08-11 | Jfeスチール株式会社 | 靭性に優れた高耐食性フェライト系ステンレス冷延鋼板およびその製造方法 |
WO2013054524A1 (ja) * | 2011-10-14 | 2013-04-18 | Jfeスチール株式会社 | フェライト系ステンレス鋼 |
JP2013227659A (ja) * | 2012-03-22 | 2013-11-07 | Nippon Steel & Sumikin Stainless Steel Corp | 耐スケール剥離性に優れたフェライト系ステンレス鋼板及びその製造方法 |
WO2014050011A1 (ja) * | 2012-09-25 | 2014-04-03 | Jfeスチール株式会社 | フェライト系ステンレス鋼 |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017172027A (ja) * | 2016-03-25 | 2017-09-28 | 新日鐵住金ステンレス株式会社 | Al含有フェライト系ステンレス鋼およびその製造方法 |
WO2018181257A1 (ja) * | 2017-03-30 | 2018-10-04 | 新日鐵住金ステンレス株式会社 | 低比重フェライト系ステンレス鋼板およびその製造方法 |
JP2018168457A (ja) * | 2017-03-30 | 2018-11-01 | 新日鐵住金ステンレス株式会社 | 低比重フェライト系ステンレス鋼板およびその製造方法 |
US11242578B2 (en) | 2017-03-30 | 2022-02-08 | Nippon Steel Stainless Steel Corporation | Ferrite-based stainless steel sheet having low specific gravity and production method therefor |
JP2020147791A (ja) * | 2019-03-13 | 2020-09-17 | 日鉄ステンレス株式会社 | 耐熱フェライト系ステンレス鋼板 |
JP7475205B2 (ja) | 2020-06-10 | 2024-04-26 | 日鉄ステンレス株式会社 | フェライト系ステンレス鋼板、フェライト系ステンレス鋼板の製造方法および自動車排気系部品 |
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