US20130126052A1 - Structural stainless steel sheet having excellent corrosion resistance at weld and method for manufacturing same - Google Patents
Structural stainless steel sheet having excellent corrosion resistance at weld and method for manufacturing same Download PDFInfo
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- US20130126052A1 US20130126052A1 US13/698,483 US201113698483A US2013126052A1 US 20130126052 A1 US20130126052 A1 US 20130126052A1 US 201113698483 A US201113698483 A US 201113698483A US 2013126052 A1 US2013126052 A1 US 2013126052A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B9/00—Measures for carrying out rolling operations under special conditions, e.g. in vacuum or inert atmosphere to prevent oxidation of work; Special measures for removing fumes from rolling mills
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Definitions
- the present invention relates to a structural stainless steel sheet having excellent welded part corrosion resistance which is suitably used as a material for a body of a railway wagon which carries coal or iron ore, for example, and a method of manufacturing the structural stainless steel sheet.
- patent document 1 discloses a Ti-containing ferritic stainless steel which exhibits excellent weld toughness thereof.
- components are designed such that the structure of the welded part has a ferrite phase and hence, there exists a drawback that weld toughness and corrosion resistance of the welded part are not sufficient.
- patent document 2 and patent document 3 disclose a technique where a proper quantity of martensitic phase is formed in a welded part by controlling a phase fraction at a high temperature thus improving workability and corrosion resistance of the welded part.
- patent document 4 discloses stainless steel which is suitable for a welding method using a carbon dioxide gas. Further, one of inventors of the present invention has proposed previously a structural stainless steel sheet which improves corrosion resistance of a welded part by properly regulating the composition using parameters which can accurately predict the structure of the welded part (patent document 5).
- the present invention has been made under such circumstances, and it is an object of the present invention to provide a structural stainless steel sheet which can be manufactured at a low cost with high efficiency, and possesses excellent welded-part corrosion resistance.
- One of inventors of the present invention has made extensive studies to overcome the above-mentioned drawback, and has found that intergranular corrosion caused by depletion of Cr in the vicinity of a grain boundary can be suppressed and a welded heat affected zone can be formed into the structure which is mainly formed of martensite by adjusting chemical components, particularly, contents of Mn and Ti, and a balance between the respective components within proper ranges, and has proposed a parameter (F value) shown in patent document 5.
- the inventors of the present invention have continued detailed studies particularly on the manufacturability based on the finding and, as a result of the studies, have found that slab cracks and scabs (surface defects) caused by inclusions can be remarkably reduced when a proper quantity of Al is added to the composition, contents of V, Ca, O are reduced to predetermined ranges or less, and an FFV value is set within a proper range as a new parameter indicative of whether or not manufacturability is favorable, and have completed the present invention.
- the present invention provides the structural stainless steel sheet having excellent welded part corrosion resistance, the structural stainless steel sheet having a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less S, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4 ⁇ (C+N) or more and 0.3% or less Ti (C, N indicating contents (mass %) of C and N), and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value and an FFV value expressed by following formulae satisfy a condition that Fvaluell and FFV value ⁇ 9.0.
- the present invention provides the structural stainless steel sheet having excellent welded part corrosion resistance which is characterized by further containing 1.0% or less Cu by mass % in addition to the above-mentioned components.
- the present invention provides the structural stainless steel sheet having excellent welded part corrosion resistance which is characterized by further containing 1.0% or less Mo by mass % in addition to the above-mentioned components.
- the present invention provides a method of manufacturing a structural stainless steel sheet, wherein a steel slab having a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less S, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4 ⁇ (C+N) or more and 0.3% or less Ti (C, N indicating contents (mass %) of C and N), and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value and an FFV value expressed by following formulae satisfy a condition that F valuell and FFV value ⁇ 9.0 is heated at a temperature of 1100 to 1300° C.
- hot rolling which includes a rough hot rolling where rolling is performed for at least 1 pass or more at a reduction rate of 30% or more in a temperature range exceeding 1000° C., or the hot rolling is performed without annealing the hot-rolled sheet or after annealing the hot-rolled sheet at a temperature of 600 to 1000° C. And, thereafter, pickling is applied to a hot-rolled sheet or an annealed hot-rolled sheet.
- the respective element symbols are contents (mass %) of the elements.
- the present invention provides the method of manufacturing a structural stainless steel sheet having excellent welded part corrosion resistance which is characterized by further containing 1.0% or less Cu by mass % in addition to the above-mentioned components.
- the present invention provides the method of manufacturing a structural stainless steel sheet having excellent welded part corrosion resistance which is characterized by further containing 1.0% or less Mo by mass % in addition to the above-mentioned components.
- the structural stainless steel sheet having excellent welded part corrosion resistance which is manufactured at a low cost and with high efficiency, and is suitably used as a material for a body of a railway wagon which carries coal or iron ore, for example.
- FIG. 1 is a graph showing the relationship between an FFV value and a surface defect occurrence rate.
- FIG. 2 is an optical micrograph showing an observation example when deep pit-shaped corrosion is recognized in a welded heat affected zone in cross section of a specimen after a sulfuric acid-copper sulfate corrosion test.
- the composition of the present invention is explained.
- the % indication is mass %.
- a structural stainless steel sheet It is necessary for a structural stainless steel sheet to contain both at least 0.01 or more C and 0.01 or more N for acquiring strength necessary for the structural stainless steel sheet.
- C, N exceed 0.03%, Cr carbide or Cr carbonitride tends to precipitate so that corrosion resistance, and particularly, corrosion resistance of a welded heat affected zone is deteriorated. Further, the welded heat affected zone is hardened thus also deteriorating toughness.
- both contents of C and N are limited to values which fall within a range from 0.01 to 0.03%
- the content of C is preferably limited to a value which falls within a range from 0.015 to 0.025%
- the content of N is preferably limited to a value which falls within a range from 0.012 to 0.02%.
- Si is an element which is used as a deoxidizer, and it is necessary to contain 0.10% or more Si to acquire such an advantage brought about by Si.
- the content of Si exceeds 0.40%, toughness of a hot-rolled steel sheet is deteriorated. Accordingly, the content of Si is limited to a value which falls within a range from 0.10 to 0.40%.
- a lower limit of the Si content is preferably set to 0.20%, and an upper limit of the Si content is preferably set to 0.30%.
- Mn is a useful element as a deoxidizer and also as a reinforcing element for securing strength necessary for a structural stainless steel sheet, and Mn is also an austenite stabilizing element at a high temperature. Further, in the present invention, Mn is an important element for controlling the microstructure of the welded heat affected zone to the martensitic structure having desired volume fraction. To allow Mn to exhibit such function, it is necessary to set the content of Mn to 1.5% or more.
- the content of Mn is limited to a value which falls within a range from 1.5 to 2.5%.
- the content of Mn is preferably limited to a value which falls within a range from 1.8 to 2.5%.
- the content of Mn is more preferably limited to a value which falls within a range from 1.85 to 2.0%.
- the content of P is preferably set small from a viewpoint of hot workability, and an allowable upper limit of the content of P is set to 0.04%.
- the upper limit of the content of P is more preferably set to 0.035% or less.
- the content of S is preferably set small from a viewpoint of hot workability and corrosion resistance, and an allowable upper limit of the content of S is set to 0.02%.
- the upper limit of the content of S is more preferably set to 0.005% or less.
- Al is an element which is added to the composition for deoxidization in general
- the inventors of the present invention have found that Al enhances manufacturability, and effectively functions to suppress the occurrence of cracks in a slab stage particularly, and a proper quantity of Al is added for allowing Al to exhibit such a function.
- the reduction of V, Ca and O, and the optimization of an FFV value are necessary as described later.
- the mechanism where the occurrence of cracks in a slab is suppressed due to the containing of Al is not entirely clarified, it is estimated that such improvement is brought about by properly regulating a phase fraction and by controlling a morphology of inclusion.
- the content of Al is limited to a value which falls within a range from 0.05 to 0.15%.
- the content of Al is preferably limited to a value which falls within a range from 0.080 to 0.150%.
- the content of Al is more preferably limited to a value which falls within a range from 0.085 to 0.120%.
- Cr is an element which forms a passive film, and is inevitable for securing corrosion resistance, particularly, corrosion resistance of a welded heat affected zone. It is necessary to set the content of Cr to 10% or more to acquire such an advantage. On the other hand, when the content of Cr exceeds 13%, not only a cost is pushed up but also it is difficult to secure a sufficient austenite phase at a high temperature in a welded part and hence, it is difficult to acquire the martensitic structure of a fraction necessary for a welded heat affected zone after welding. As a result, deterioration of intergranular corrosion resistance at the welded heat affected zone is brought about. Accordingly, the content of Cr is limited to a value which falls within a range from 10 to 13%. The content of Cr is preferably limited to a value which falls within a range from 10.5 to 12.5%.
- Ni is set to 0.5% or more to secure strength and toughness.
- Ni is an expensive element and hence, an upper limit of the content of Ni is set to 1.0% from an economical point of view.
- Ni is, in the same manner as Mn, an austenite stabilizing element at a high temperature and hence, Ni is useful in controlling the microstructure of a welded heat affected zone to the martensitic structure having desired volume fraction.
- Mn an austenite stabilizing element at a high temperature
- Ni is useful in controlling the microstructure of a welded heat affected zone to the martensitic structure having desired volume fraction.
- this advantage can be sufficiently acquired due to the addition of Mn and hence, it is reasonable to limit the content of Ni to a value which falls within a range from 0.5 to 1.0%.
- the content of Ni is preferably limited to a value which falls within a range from 0.60 to 1.0%.
- the content of Ni is more preferably limited to a value which falls within a range from 0.60 to 0.90%.
- Ti is an important element for acquiring excellent welded part corrosion resistance in the present invention, and is an element particularly inevitable for enhancing intergranular corrosion resistance of a welded heat affected zone.
- Ti has an advantage that Ti precipitates and fixes C, N in steel as carbide, nitride or carbonitride of Ti (hereinafter three kinds of compositions consisting of carbide, nitride and carbonitride being collectively referred to as carbonitride or the like) thus suppressing the generation of carbonitride or the like of Cr.
- the content of Ti is limited to 4 ⁇ (C+N) or more and 0.3% or less.
- the content of Ti is more preferably limited to a value which falls within a range from 0.180 to 0.230%. That is, it is effective for the steel sheet to reduce C, N such that the content of Ti simultaneously satisfies 4 ⁇ (C+N) or more.
- V is added to a steel sheet as an impurity in a Cr raw material or the like, and there may be case where V is added to a steel sheet unintentionally.
- Ca forms an inclusion of a low melting point and hence, Ca becomes a cause of a surface defect particularly attributed to the inclusion. Accordingly, in the present invention, it is necessary to strictly restrict the content of Ca, and an upper limit of the content of Ca is limited to 0.0030%. It is preferable that the content of Ca is as small as possible, and the content of Ca may be preferably limited to 0.0010% and may be more preferably limited to 0.0002% or less. However, the selection of the raw material or the like becomes necessary and hence, such limitation of the content of Ca becomes economically disadvantageous.
- an upper limit of the content O is set to 0.0080%.
- the upper limit of the content of O is more preferably set to 0.060% or less.
- corrosion resistance and productivity can be largely improved by setting an F value and an FFV value described hereinafter to within proper ranges.
- the F value is expressed by Cr+2 ⁇ Si+4 ⁇ Ti ⁇ 2 ⁇ Ni ⁇ Mn ⁇ 30 ⁇ (C+N) (respective element symbols being contents of the elements (mass %)), and is a parameter for estimating the microstructure of a welded heat affected zone at the time of welding.
- the F value is a parameter for estimating a volume fraction of the martensitic structure (a residual rate of the ferrite structure).
- a part of a steel sheet such as a welded heat affected zone which is exposed to a high temperature
- a part of the zone is transformed into austenite (or a portion of the part is further transformed into ⁇ ferrite (delta ferrite)), and these phase are transformed into martensite in a cooling step.
- the rate is influenced by a quantitative balance between ferrite stabilizing elements (ferrite formation elements) and austenite stabilizing elements (austenite formation elements).
- ferrite formation elements ferrite formation elements
- austenite stabilizing elements austenite formation elements.
- elements having a positive coefficient Cr, Si, Ti
- elements having a negative coefficient Ni, Mn, C, N
- the larger the F value the more the ferrite structure is likely to remain (the larger a volume fraction of the ferrite structure becomes, that is, the smaller a volume fraction of the martensitic structure becomes), while the smaller the F value, the more scarcely the ferrite structure remains (the smaller a volume fraction of the ferrite becomes, that is, the larger a volume fraction of the martensitic structure becomes).
- the optimization of content is attempted by investigating the relationship between the F value and a volume fraction of the martensitic structure of the welded heat affected zone and by evaluating corrosion resistance of an area in the vicinity of the welded heat affected zone by a sulfuric acid-copper sulfate corrosion test.
- the above-mentioned F value is limited to 11 or less (martensite volume fraction: 40% or more).
- the above-mentioned F value is preferably limited to 10.5 or less (martensite volume fraction: 60% or more), and is more preferably limited to 10 or less.
- a lower limit of the F value is preferably set to 5.0 or more, and is more preferably set to 6.0 or more.
- the FFV value is expressed by Cr+3 ⁇ Si+16 ⁇ Ti+Mo+2 ⁇ Al ⁇ 2 ⁇ Mn ⁇ 4 ⁇ (Ni+Cu) ⁇ 40 ⁇ (C+N)+20 ⁇ V (the respective element symbols being contents of the elements (mass %)).
- the FFV is newly introduced in the present invention as an index for indicating manufacturability.
- the FFV value is set by taking a phase balance during hot rolling into consideration. By adjusting the components as described above, particularly by regulating the content of Al and upper limits of V, Ca, O and, thereafter, by setting this FFV value smaller, the occurrence of surface defects caused by cracks in a slab stage or inclusions can be remarkably reduced.
- the significant technical feature of present invention lies in succeeding in largely suppressing the lowering of a yield rate caused by the occurrence of a surface defect by optimizing a new parameter which takes an Al quantity which was not taken into consideration at the time of inventing the F value into consideration.
- the mechanism of the improvement of the manufacturability by optimization of the FFV value is not entirely clarified, since the manufacturability is largely improved by limiting the FFV value to 9.0 or less, the FFV value is set to 9.0 or less.
- the FFV value is preferably set to 8.5 or less.
- the control of cracks in a slab stage and inclusions is important for reducing surface defects. It is because, with respect to the occurrence of surface defects, portions such as cracks or scabs which largely lower a yield rate not only deteriorate the appearance but also become a starting point of the occurrence of rust and hence, it is necessary to cut off the portions where cracks or scab occur at the time of shipping the steel sheet as a product.
- the above-mentioned formula on the FFV value includes Mo, V, Cu, there may be a case where these components are not added to the steel. When these contents are not added to the steel, the FFV value is calculated by setting the contents of the components not contained in the steel to 0%.
- FIG. 1 shows the relationship between the FFV value and a surface defect occurrence rate.
- the surface defect occurrence rate was calculated based on a length of a portion where defects occur with respect to a total length of a coil. It is understood that by limiting the FFV value within a range of 9.0 or below, the occurrence of surface defects can be remarkably suppressed.
- the steel may contain Cu within a following range when necessary in addition to the above-mentioned components.
- Cu is an element which enhances corrosion resistance, and is an element which particularly reduces crevice corrosion. Accordingly, Cu can be added when the steel is requested to possess high corrosion resistance. However, when the content of Cu exceeds 1.0%, hot workability is deteriorated, and also a phase balance at a high temperature collapses and hence, it is difficult for a welded heat affected zone to acquire the desired microstructure. Accordingly, when Cu is added to the composition, an upper limit of the content of Cu is set to 1.0%. To allow Cu to exhibit a sufficient corrosion resistance enhancing effect, it is effective to set the content of Cu to 0.3% or more. The content of Cu is more preferably set to a value which falls within a range from 0.3 to 0.5%.
- Mo is an element which enhances corrosion resistance, and can be added to the composition when a steel sheet is requested to possess high corrosion resistance particularly.
- an upper limit of the content of Mo is set to 1.0%.
- the content of Mo is more preferably set to a value which falls within a range from 0.1 to 1.0%.
- Nb is a strong stabilizing element and largely collapses a phase balance by combining with C or N and hence, Nb is not added in the present invention.
- a balance other than the above-prescribed elements is constituted of Fe and unavoidable impurities.
- a martensite in volume fraction of the welded heat affected zone becomes 40% or more.
- the martensite fraction of the welded heat affected zone becomes 60% or more.
- the martensite in volume fraction of the welded heat affected zone becomes 80% or more in this case.
- 50% or more of a matrix steel (base material) portion in volume fraction is formed of the ferrite structure.
- the remaining structure is formed of, particularly in a hot-rolled state, the structure where a martensite phase and a residual ⁇ phase are present and partially contains carbonitride or the like.
- a hot-rolled annealed sheet which is manufactured as described later such that contents of components are set to fall within a proper composition range and hot-rolled-sheet annealing is applied under a proper annealing condition, almost 100% of the structure has the ferrite-phase structure in volume fraction and hence, the structure possesses the excellent workability.
- the method of manufacturing a stainless steel sheet of the present invention may be performed in accordance with a given method and is not specifically limited.
- a method which can manufacture a stainless steel sheet with high efficiency a method where a molten steel having the above-mentioned composition is formed into a slab by continuous casting or the like, the slab is formed into a hot-rolled coil, the hot-rolled coil is annealed when necessary and, thereafter, descaling (shot blasting, pickling and the like) is performed thus manufacturing a stainless steel sheet according to the present invention is recommended.
- a molten steel adjusted to the composition of the present invention is produced by a known commonly used melting furnace such as a steel converter or an electric furnace and, thereafter, the molten steel is refined by a known refining method such as a vacuum degassing method (RH method), a VOD (Vacuum Oxygen Decarburization) method or an AOD (Argon Oxygen Decarburization) method, and the molten steel is formed into a steel slab (raw steel material) by a continuous casting or an ingot-making/blooming method. It is preferable to adopt continuous casting as a casting method from a viewpoint of productivity and quality. Further, a thickness of a slab may preferably be set to 100mm or more for securing a reduction ratio in hot coarse rolling described later. It is more preferable to set the thickness of the slab within a range of 200 mm or more.
- the steel slab is heated up to a temperature of 1100 to 1300° C. and, thereafter, is subjected to hot rolling whereby a hot-rolled steel sheet is formed. It is desirable to set the slab heating temperature high for enhancing surface roughness resistance of the hot-rolled sheet or anti-ridging property or ridging property after annealing in cold rolling. However, when the slab heating temperature exceeds 1300° C., slag sag becomes conspicuous, and crystal grains become coarse thus deteriorating toughness of the hot-rolled sheet.
- a hot rough rolling step it is preferable to perform rolling at a reduction rate of 30% or more in a temperature range exceeding 1000° C. for at least 1 pass or more. Due to this rolling with a high reduction rate, the grain (crystal) structure of a steel sheet is made fine so that toughness of the steel sheet is enhanced.
- hot finish rolling is performed in accordance with a given method (under a condition of usual hot finish rolling).
- a hot-rolled sheet having a sheet thickness of approximately 2.0 to 8.0 mm which is manufactured by hot rolling is used as a structural material directly or through pickling without annealing.
- Pickling may be applied to the hot-rolled sheet after the hot-rolled sheet is annealed at a temperature of 600 to 1000° C.
- an annealing temperature of the hot-rolled sheet is below 600° C., there may be a case where a martensite phase or a residual ⁇ phase which has a possibility of existing in a hot-rolled state remains and hence, the ferrite structure becomes 50% or less in terms of a volume fraction whereby the steel sheet cannot acquire the sufficient workability.
- Annealing of the hot-rolled sheet may preferably be performed such that the hot-rolled sheet is held at a predetermined temperature of 600 to 1000° C. for 1 hour or more by so-called box annealing. Further, when the annealing temperature becomes excessively high, there is a case where the hot-rolled sheet enters a temperature at which the ⁇ transformation occurs and hence, the excessively high temperature is not preferable. Accordingly, it is necessary to adjust the composition within a proper range and to select a proper temperature range corresponding to the composition.
- the annealing temperature is mainly set to a value which falls within 600 to 900° C., almost 100% of the hot-rolled sheet becomes a ferrite phase in terms of a volume fraction and hence, it is preferable to set the annealing temperature within this temperature range.
- Stainless steel having the composition shown in Table 1 is formed into slabs having a thickness of 200 mm through a steel converter, VOD and continuous casting. These slabs are heated at a temperature of 1180° C. and, thereafter, the slab is formed into a coil-shaped hot-rolled sheet having a sheet thickness of 5.0 mm by hot rolling. A hot rolling finish (delivering) temperature is set to 900° C., and a coiling temperature after hot rolling is set to 700° C. The obtained hot-rolled steel sheet is subjected to annealing at a temperature of 690° C. for 10 hours and, thereafter, scales are removed from the hot-rolled steel sheet by shot blasting and pickling.
- T-shaped specimens each of which is formed of a lower plate and a vertical plate are assembled, and both side one pass fillet welding (gas metal arc welding, shielding gas: 98 volume % Ar-2 volume % O 2 , flow rate: 20 litter/min) is applied to the T-shaped specimens thus forming three fillet welding specimens.
- MGS-309LS made by Kobe steel limited is used as a welding rod, and a welding input heat is set to a value which falls within a range from 0.4 to 0.8 kJ/mm.
- Corrosion test specimens are sampled from these filled welded parts of these fillet welding specimens, and the corrosion specimens are subjected to a sulfuric acid-copper sulfate corrosion test (Modified Strauss test in accordance with ASTM A262 practice E and ASTM A763 practice Z, a test liquid: Cu/6% CuSO 4 /0.5% H 2 SO 4 , a specimen with polished end surfaces being immersed in the boiling test liquid for 20 hours), and a corrosion state of an area in the vicinity of a welded heat affected zone is observed.
- a sulfuric acid-copper sulfate corrosion test Modified Strauss test in accordance with ASTM A262 practice E and ASTM A763 practice Z, a test liquid: Cu/6% CuSO 4 /0.5% H 2 SO 4 , a specimen with polished end surfaces being immersed in the boiling test liquid for 20 hours
- FIG. 2 is an optical micrograph showing an observation example of a cross section of the specimen after the sulfuric acid-copper sulfate corrosion test.
- the evaluation “C” is given to a case where intergranular corrosion is observed or pit-shaped corrosion far deeper than intergranular corrosion is observed in the welded heat affected zone as shown in the photograph.
- the evaluation “B” is given to a case where slight corrosion is observed in the welded heat affected zone.
- the evaluation “A” is given to a case where corrosion is not observed by the observation using an optical microscope. Further, a surface state of the hot-rolled annealed sheet after pickling is observed over the whole length of the sheet.
- the present invention steel is used in a state of a hot-rolled sheet or a hot-rolled annealed sheet, the occurrence of scabs largely lowers a yield rate. This is because the scab portions not only exhibit poor appearance but also become a starting point of the occurrence of rust and hence, it is necessary to cut off portions corresponding to the scab portions at the time of shipping the hot-rolled sheet or the hot-rolled annealed sheet as a product.
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- 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)
- Arc Welding In General (AREA)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2010124059 | 2010-05-31 | ||
JP2010-124059 | 2010-05-31 | ||
PCT/JP2011/062640 WO2011152475A1 (fr) | 2010-05-31 | 2011-05-26 | Tôle d'acier inoxydable de construction ayant une excellente résistance à la corrosion dans la partie soudée, et son procédé de production |
Publications (1)
Publication Number | Publication Date |
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US20130126052A1 true US20130126052A1 (en) | 2013-05-23 |
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ID=45066832
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/698,483 Abandoned US20130126052A1 (en) | 2010-05-31 | 2011-05-26 | Structural stainless steel sheet having excellent corrosion resistance at weld and method for manufacturing same |
Country Status (12)
Country | Link |
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US (1) | US20130126052A1 (fr) |
EP (1) | EP2578715B1 (fr) |
JP (1) | JP4893866B2 (fr) |
KR (1) | KR101409291B1 (fr) |
CN (1) | CN102933732B (fr) |
AU (1) | AU2011259992B2 (fr) |
BR (1) | BR112012030684B1 (fr) |
CA (1) | CA2799696C (fr) |
ES (1) | ES2643150T3 (fr) |
RU (1) | RU2522065C1 (fr) |
TW (1) | TWI439555B (fr) |
WO (1) | WO2011152475A1 (fr) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3859044A4 (fr) * | 2018-11-06 | 2021-12-22 | Posco | Tôle d'acier laminée à chaud présentant une excellente résistance aux chocs à basse température, et procédé de fabrication associé |
Families Citing this family (4)
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TW201418549A (zh) * | 2012-11-12 | 2014-05-16 | Shehkai Prec Co Ltd | 複合式混凝土之螺絲錨栓 |
WO2015064077A1 (fr) | 2013-10-31 | 2015-05-07 | Jfeスチール株式会社 | Acier inoxydable diphasique ferrite-martensite, et son procédé de fabrication |
WO2015064128A1 (fr) * | 2013-10-31 | 2015-05-07 | Jfeスチール株式会社 | Acier inoxydable à deux phases ferrite-martensite présentant une résilience aux basses températures, et son procédé de production |
CN108690936B (zh) * | 2018-06-13 | 2020-12-01 | 燕山大学 | 用于焊接高锰钢辙叉与钢轨的不锈钢钢轨材料及制备方法 |
Citations (2)
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JP2001348650A (ja) * | 2000-06-06 | 2001-12-18 | Kawasaki Steel Corp | 耐初期発錆性に優れた土木・建築構造用ステンレス熱延鋼帯 |
US20090098009A1 (en) * | 2006-07-04 | 2009-04-16 | Masuhiro Fukaya | Low Chromium Stainless Steel Superior in Corrosion Resistance of Multipass Welded Heat Affected Zones and Its Method of Production |
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US3650731A (en) * | 1969-01-31 | 1972-03-21 | Allegheny Ludlum Steel | Ferritic stainless steel |
SU595420A1 (ru) * | 1976-12-06 | 1978-02-28 | Предприятие П/Я А-1147 | Сталь |
JPS6199628A (ja) * | 1984-10-19 | 1986-05-17 | Kawasaki Steel Corp | オ−ステナイト系ステンレス鋼板または鋼帯の製造方法 |
JPH03249150A (ja) * | 1990-02-27 | 1991-11-07 | Nippon Steel Corp | 溶接部の靭性に優れたフェライト系ステンレス鋼 |
SU1723191A1 (ru) * | 1990-06-25 | 1992-03-30 | Волгоградский Политехнический Институт | Нержавеюща сталь |
JP2000080416A (ja) * | 1998-08-31 | 2000-03-21 | Kawasaki Steel Corp | 溶接性および耐食性に優れたラインパイプ用高Crマルテンサイト溶接鋼管の製造方法 |
US6884388B2 (en) * | 2000-08-31 | 2005-04-26 | Jfe Steel Corporation | Low carbon martensitic stainless steel and method for production thereof |
JP2002121652A (ja) * | 2000-10-12 | 2002-04-26 | Kawasaki Steel Corp | 自動車足回り用Cr含有鋼 |
JP4457492B2 (ja) | 2000-11-29 | 2010-04-28 | Jfeスチール株式会社 | 加工性と溶接性に優れたステンレス鋼 |
CN100532611C (zh) * | 2003-07-22 | 2009-08-26 | 住友金属工业株式会社 | 马氏体不锈钢 |
EP2289662A3 (fr) * | 2003-09-05 | 2012-12-05 | Sumitomo Metal Industries, Ltd. | Structure soudée dotée d'une résistance améliorée au craquage de la corrosion sous tension |
JP2006219717A (ja) * | 2005-02-09 | 2006-08-24 | Nippon Steel Corp | 耐変形性、表面特性、溶接性が著しく良好な容器用鋼板及びその製造方法 |
JP4740021B2 (ja) * | 2006-04-20 | 2011-08-03 | 新日鐵住金ステンレス株式会社 | 形状凍結性に優れるCr含有薄鋼板およびその製造方法 |
-
2011
- 2011-05-26 RU RU2012157554/02A patent/RU2522065C1/ru active
- 2011-05-26 AU AU2011259992A patent/AU2011259992B2/en active Active
- 2011-05-26 US US13/698,483 patent/US20130126052A1/en not_active Abandoned
- 2011-05-26 BR BR112012030684-7A patent/BR112012030684B1/pt active IP Right Grant
- 2011-05-26 EP EP11789877.5A patent/EP2578715B1/fr active Active
- 2011-05-26 WO PCT/JP2011/062640 patent/WO2011152475A1/fr active Application Filing
- 2011-05-26 CN CN201180026476.7A patent/CN102933732B/zh active Active
- 2011-05-26 KR KR1020127032216A patent/KR101409291B1/ko active IP Right Grant
- 2011-05-26 JP JP2011117803A patent/JP4893866B2/ja active Active
- 2011-05-26 CA CA2799696A patent/CA2799696C/fr active Active
- 2011-05-26 ES ES11789877.5T patent/ES2643150T3/es active Active
- 2011-05-31 TW TW100119016A patent/TWI439555B/zh active
Patent Citations (2)
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JP2001348650A (ja) * | 2000-06-06 | 2001-12-18 | Kawasaki Steel Corp | 耐初期発錆性に優れた土木・建築構造用ステンレス熱延鋼帯 |
US20090098009A1 (en) * | 2006-07-04 | 2009-04-16 | Masuhiro Fukaya | Low Chromium Stainless Steel Superior in Corrosion Resistance of Multipass Welded Heat Affected Zones and Its Method of Production |
Non-Patent Citations (1)
Title |
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JP 2001-348650 machine translation * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3859044A4 (fr) * | 2018-11-06 | 2021-12-22 | Posco | Tôle d'acier laminée à chaud présentant une excellente résistance aux chocs à basse température, et procédé de fabrication associé |
Also Published As
Publication number | Publication date |
---|---|
TWI439555B (zh) | 2014-06-01 |
AU2011259992A1 (en) | 2012-12-20 |
BR112012030684B1 (pt) | 2018-08-14 |
KR101409291B1 (ko) | 2014-06-18 |
RU2012157554A (ru) | 2014-07-20 |
CA2799696A1 (fr) | 2011-12-08 |
JP2012012702A (ja) | 2012-01-19 |
KR20130034025A (ko) | 2013-04-04 |
ES2643150T3 (es) | 2017-11-21 |
TW201207128A (en) | 2012-02-16 |
EP2578715A4 (fr) | 2015-08-19 |
EP2578715A1 (fr) | 2013-04-10 |
CN102933732B (zh) | 2016-06-29 |
CN102933732A (zh) | 2013-02-13 |
EP2578715B1 (fr) | 2017-07-12 |
CA2799696C (fr) | 2015-11-17 |
RU2522065C1 (ru) | 2014-07-10 |
JP4893866B2 (ja) | 2012-03-07 |
AU2011259992B2 (en) | 2013-12-19 |
BR112012030684A2 (pt) | 2017-12-05 |
WO2011152475A1 (fr) | 2011-12-08 |
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