Abstract: Provided is a ferritic stainless steel that has excellent corrosion resistance and displays good brazing properties when brazing is carried out at high temperature using a Ni-containing brazing metal. These effects are obtained as a result of the steel having a chemical composition containing, in mass %: 0.003%-0.020% of C; 0.05%-1.00% of Si; 0.10%-0.50% of Mn, 0.04% or less of P; 0.01% or less of S; 16.0%-25.0% of Cr; 0.05%-0.60% of Ni; 0.25%-0.45% of Nb; 0.005%-0.15% of Al; 0.005%-0.030% of N; and at least one selected from 0.50%-2.50% of Mo and 0.05%-0.80% of Cu, the balance being Fe and incidental impurities, and as a result of a nitrogen-enriched layer being created that has a nitrogen concentration peak value of 0.03 to 0.30 mass % at a depth of within 0.05 ?m of a surface of the steel.
Abstract: The invention proposes a method for heating a steel sheet wherein the generation of buckling can be prevented regardless of presence or absence of rolls restraining the steel sheet by antecedently heating the widthwise central portion of the steel sheet with a solenoid type induction heating coil having a convex form projected onto the surface of the steel sheet toward an upstream side in rapidly heating the continuously traveling steel sheet, whereby an isotherm of the steel sheet in the heating is a convex form toward the upstream side, so that a large wrinkle is generated on the steel sheet, and also proposes a heating apparatus used in this method.
Abstract: A steel plate comprising, by mass %: C: 0.03% to 0.12%, Si: 0.5% or less, Mn: 1.0% to 2.0%, P: 0.015% or less, S: 0.0005% to 0.0050%, Al: 0.005% to 0.060%, Ni: 0.5% to 2.0%, Ti: 0.005% to 0.030%, N: 0.0015% to 0.0065%, O: 0.0010% to 0.0050%, Ca: 0.0005% to 0.0060%, and optionally one or two or more of Cu and the like. Ti/N, Ceq, Pcm, and ACR are in particular ranges, a base metal of the plate has an effective grain size of 20 ?m or less at half the thickness of the plate, and the plate contains a particular number of complex inclusions at ¼ and ½ of the thickness of the plate. The complex inclusions comprise a sulfide containing Ca and Mn and an oxide containing Al and having an equivalent circular diameter of 0.1 ?m or more.
Abstract: A high-strength hot-dip galvanized steel sheet excellent in formability includes, on the basis of mass percent, 0.05-0.3% C, 1.4% or less (including 0%) Si, 0.08%-3% Mn, 0.003-0.1% P, 0.07% or less S, 0.1-2.5% Al, 0.1-0.5% Cr, and 0.007% or less N, Si+Al?0.5%, and the balance being Fe and incidental impurities, wherein the steel sheet has a retained austenite content of 3% or more by volume fraction, a stretch-flange formability ?>50% and wherein the average aspect ratio (major axis/minor axis) of retained austenite grains is less than 2.5.
Abstract: A high-strength galvanized steel sheet that includes a chemical composition containing, by mass %, C: 0.15% or more and 0.25% or less, Si: 0.50% or more and 2.5% or less, Mn: 2.3% or more and 4.0% or less, P: 0.100% or less, S: 0.02% or less, Al: 0.01% or more and 2.5% or less, and Fe and inevitable impurities. The steel sheet having a microstructure containing, by an area percentage basis, a tempered martensite phase: 30% or more and 73% or less, a ferrite phase: 25% or more and 68% or less, a retained austenite phase: 2% or more and 20% or less, and other phases: 10% or less (including 0%), the other phases containing a martensite phase: 3% or less (including 0%) and a bainitic ferrite phase: less than 5% (including 0%).
Abstract: A method for manufacturing a high strength galvanized steel sheet which has a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C: 0.03% to 0.35%, Si: 0.01% to 0.50%, Mn: 3.6% to 8.0%, Al: 0.001% to 1.000%, P?0.10%, S?0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, is provided. In annealing and galvanization treatment of the base steel sheet in a continuous galvanizing line, the maximum steel sheet temperature in an annealing furnace is 600° C. or higher and 750° C. or lower, the steel sheet transit time in a temperature region of the steel sheet temperature of 600° C. or higher and 750° C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be ?10° C. or higher.
Abstract: Provided is a ferritic stainless steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.010% or less, Si: 1.0% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 17.0% or more and 18.5% or less, N: 0.015% or less, Nb: 0.40% or more and 0.80% or less, Ti: 0.10% or more and 0.40% or less, Al: 0.20% or less, Ni: 0.05% or more and 0.40% or less, Co: 0.01% or more and 0.30% or less, Mo: 0.02% or more and 0.30% or less, Cu: 0.02% or more and 0.40% or less, and the balance being Fe and inevitable impurities, in which expression (1) below is satisfied. C %+N %: 0.018% or less??(1) In expression (1), C % and N % respectively denote the contents (mass %) of C and N.
Abstract: A threaded joint for pipes including a pin and a box, characterized in that the relationship 0.05 degrees??sb??sp?2.0 degrees is satisfied, where ?sb is an angle of an insertion surface of the female thread on the box side relative to a plane perpendicular to an axis of pipe, and ?sp is an angle of an insertion surface of the male thread, which faces the insertion surface of the female thread, on the pin side relative to the plane perpendicular to the axis of pipe.
Abstract: A high toughness and high tensile strength thick steel plate has a plate thickness of 100 mm or more, wherein a reduction of area in a center of the plate thickness by tension in a plate thickness direction is 40% or more. Thus, a high tensile strength thick steel plate with excellent strength and toughness in a center of the plate thickness can be obtained with no need for a larger production line, even in the case of producing a high strength thick steel plate for which the addition amount of alloying element needs to be increased.
Abstract: Provided is a method for manufacturing a zinc-based coated steel sheet having excellent press formability. The method includes an oxide layer-forming step of bringing the zinc-based coated steel sheet into contact with an acidic solution, holding the zinc-based coated steel sheet for 1 second to 60 seconds, and then water-washing the zinc-based coated steel sheet and a neutralization step of holding a zinc-based oxide layer formed in the oxide layer-forming step for 0.5 seconds or more in such a state that a surface of the zinc-based oxide layer is in contact with an alkaline aqueous solution, water-washing the zinc-based oxide layer, and then drying the zinc-based oxide layer. The acidic solution contains HF2Na and/or HF2K in a total amount of 0.10 g/L to 5.0 g/L.
Abstract: A plug for rolling of a seamless steel pipe, the plug having an oxide layer composed of a cobalt-base oxide on a surface of a coating layer formed by coating a surface of a base metal with cobalt or a cobalt-base alloy, a method for manufacturing the plug and a method for manufacturing a seamless steel pipe using the plug.
Abstract: An abrasion-resistant steel plate that can achieve both gas cutting cracking resistance and abrasion resistance at low cost is provided. An abrasion-resistant steel plate comprises: a chemical composition containing, in mass %, C: more than 0.34% and 0.50% or less, Si: 0.01% to 1.0%, Mn: 0.30% to 2.00%, P: 0.015% or less, S: 0.005% or less, Cr: 0.01% to 2.00%, Al: 0.001% to 0.100%, N: 0.01% or less, and a balance consisting of Fe and inevitable impurities; and a microstructure in which a volume fraction of martensite at a depth of 1 mm from a surface of the abrasion-resistant steel plate is 90% or more, and a prior austenite grain size at the mid-thickness of the abrasion-resistant steel plate is 80 ?m or less, wherein hardness at a depth of 1 mm from the surface of the abrasion-resistant steel plate is 560 HBW 10/3000 or more in Brinell hardness, and a concentration [Mn] of Mn in mass % and a concentration [P] of P in mass % in a plate thickness central segregation area satisfy 0.04[Mn]+[P]<0.45.
Abstract: A punch processing method for electrical steel sheets to manufacture core segments includes: stacking a plurality of electrical steel sheets; and punching out the plurality of electrical steel sheets in a stacked state simultaneously to manufacture the core segments, wherein in a case where the core segments are applied to a stator core in which a maximum magnetic flux density at a tooth portion is to be higher than a maximum magnetic flux density at a back yoke portion, degrees of Vickers hardness of an electrical steel sheet located second from a bottom side and above in the stacked state are set to 180 HV or higher, and 10 HV or higher than a value of degree of Vickers hardness of an electrical steel sheet located on the bottom side in the stacked state.
August 22, 2017
October 10, 2019
JFE STEEL CORPORATION
Kunihiro SENDA, Masanori UESAKA, Yoshihiko ODA
Abstract: A method for producing a cold-rolled steel strip with a yield ratio Re/Rm of at least 0.7, the cold-rolled steel product including iron, unavoidable impurities and (in wt. %) C: 0.05-0.20%, Si: 0.25-1.00%, Mn: 1.0-3.0%, Al: 0.02-1.5%, Cr: 0.1-1.5%, N: <0.02%, P: <0.03%, S: <0.05% and optionally one or more of Ti, Mo, Nb, V, and B, Ti: up to 0.15%, Mo: <2%, Nb: <0.1%, V: <0.12%, and B: 0.0005-0.003%. The cold-rolled flat steel product undergoes heat treatment for 4.5-24 hours at a temperature of 150-400° C. Also, a cold rolled flat steel product discussed above having a structure including at least two phases, selected from (in vol. %) at least 10% tempered martensite, <10% bainite, <10% residual austenite and remainder ferrite, a yield ratio of at least 0.7, a tensile strength of ?750 MPa and a hole expansion of at least 18%.
April 14, 2015
Date of Patent:
October 8, 2019
THYSSENKRUPP STEEL EUROPE AG, JFE STEEL CORPORATION
Brigitte Hammer, Frank Hisker, Thomas Heller, Almir Dzafic, Richard G. Thiessen, Shinjiro Kaneko, Fusae Shiimori
Abstract: A high-strength cold-rolled steel sheet has a composite structure containing 0.15 to 0.25% by mass of C, 1.8 to 3.0% by mass of Mn, and 0.0003 to 0.0050% by mass of B, and having a ferrite volume fraction of 20% to 50%, a retained austenite volume fraction of 7% to 20%, a martensite volume fraction of 1% to 8%, and the balance containing bainite and tempered martensite, and in the composite structure, ferrite has an average crystal grain diameter of 5 ?m or less, retained austenite has an average crystal grain diameter of 0.3 to 2.0 ?m and an aspect ratio of 4 or more, martensite has an average crystal grain diameter of 2 ?m or less, a metal phase containing both bainite and tempered martensite has an average crystal grain diameter of 7 ?m or less, the ratio of the volume fraction of tempered martensite to the volume fraction of a metal structure other than ferrite is 0.60 to 0.85, and the average C concentration in retained austenite is 0.65% by mass or more.
Abstract: Provided is a hot-pressed member excellent in terms of paint adhesiveness and a method of manufacturing the hot-pressed member. A hot-pressed member has a coating layer containing Zn and Ni on the surface of a steel sheet of which the member is formed, an oxide film containing Zn on the coating layer, and a void formation rate is 80% or less for voids formed between the coating layer and the oxide film.
Abstract: An ultrasonic flaw detection apparatus includes: a seam detection unit that captures a thermal image of a welded seam portion of an electric resistance welded pipe; an ultrasonic flaw detection sensor head that includes an ultrasonic probe that performs ultrasonic flaw detection on the welded seam portion; a seam position calculation unit that calculates a seam position and a bead cutting position of the electric resistance welded pipe; a bead cutting band detection unit that detects a bead cutting band of the electric resistance welded pipe; a bead cutting position calculation unit that calculates a bead cutting position of the electric resistance welded pipe; a tracking movement amount calculation unit that calculates a tracking movement amount of the ultrasonic flaw detection sensor head; and a sensor head driving unit that moves the ultrasonic flaw detection sensor head to track the welded seam portion according to the tracking movement amount.
Abstract: Provided is a treatment solution for chromium-free tension coating that can simultaneously achieve excellent moisture absorption resistance and a high iron loss reduction effect obtained by imparting sufficient tension, by using an inexpensive Ti source instead of expensive Ti chelate. The treatment solution for chromium-free tension coating contains: one or more of phosphates of Mg, Ca, Ba, Sr, Zn, Al, and Mn; colloidal silica in an amount of 50 parts by mass to 120 parts by mass per 100 parts by mass of the phosphate in terms of solid content of SiO2; Ti source in an amount of 30 parts by mass to 50 parts by mass per 100 parts by mass of the phosphate in terms of solid content of TiO2; and H3PO4, and the number of moles of metallic elements in the phosphate and of phosphorus in the treatment solution satisfy: 0.20?([Mg]+[Ca]+[Ba]+[Sr]+[Zn]+[Mn]+1.5[Al])/[P]?0.45??(1).
Abstract: A stainless steel sheet for fuel cell separators comprises: a predetermined chemical composition; and Cr-containing fine precipitates at a steel sheet surface, wherein an average equivalent circular diameter of the fine precipitates is 20 nm or more and 500 nm or less, and a number of the fine precipitates existing per 1 ?m2 at the steel sheet surface is three or more.
Abstract: Disclosed is a method of producing a hot-dip metal coated steel strip capable of sufficiently suppressing generation of bath wrinkles and producing high-quality hot-dip metal coated steel strip at low cost. The disclosed method of producing a hot-dip metal coated steel strip includes: blowing a gas from a pair of gas wiping nozzles 20A and 20B to a steel strip S while being pulled up from a molten metal bath 14 so as to adjust a coating weight of molten metal on both sides of the steel strip S, in which each of the gas wiping nozzles 20A and 20B includes an injection port portion that is installed downward with respect to a horizontal plane such that an angle formed by the injection port portion and the horizontal plane is 10° or more and 75° or less, and has a header pressure below 30 kPa.