High-strength galvanized steel sheet, high strength member, and method for manufacturing the same

Hot-rolled steel sheet having excellent durability and method for manufacturing same

Component for contacting hydrogen

High-strength steel sheet with excellent ductility and hole-expandability

Cold rolled steel sheet and a method of manufacturing thereof

Cold rolled and heat treated steel sheet and a method of manufacturing thereof

STEEL

Offset link for roller chain with enhanced strength

Method for the manufacture of a coated steel sheet

Method for manufacturing a high-strength steel sheet and sheet obtained by the method

High-strength, hot-rolled flat steel product with high edge cracking resistance and, at the same time, high bake-hardening potential, and method for producing such a flat steel product

Steel material for low yield ratio, high-strength steel pipe having excellent low-temperature toughness, and manufacturing method therefor

High-strength cold-rolled steel sheet and method for manufacturing same

Cold rolled and coated steel sheet and a method of manufacturing thereof

High-strength hot-rolled plated steel sheet, and method for producing same

Method for producing a hot strip of a bainitic multi-phase steel having a Zn—Mg—Al coating, and a corresponding hot strip

Method for producing a steel part and corresponding steel part

Wear-resistant steel having excellent hardness and impact toughness, and method for producing same

High-strength steel sheet having excellent impact resistance, and method for manufacturing same

Hot-rolled steel plate and method for manufacturing same

Hot stamped component, precoated steel sheet used for hot stamping and hot stamping process

High-strength galvanized steel sheet and method for manufacturing same

ULTRAHIGH STRENGTH COLD-ROLLED STEEL SHEET AND MANUFACTURING METHOD THEREOF

Hot rolled steel sheet and method for producing same

Cold rolled and heat treated steel sheet and a method of manufacturing thereof

High-strength medium manganese steel for warm stamping and method for manufacturing same

ABRASION RESISTANT STEEL AND METHOD FOR PRODUCING SAME

Galvannealed steel sheet

Cryogenic steel plate and method for manufacturing same

Steel reinforcing bar and production method therefor

HIGH STRENGTH STEEL PLATE AND MANUFACTURING METHOD THEREFOR

High-strength steel sheet having excellent processability and method for manufacturing same

High friction rolling of thin metal strip

High-strength steel having excellent low-yield-ratio characteristics, and manufacturing method therefor

STEEL SECTION HAVING A THICKNESS OF AT LEAST 100MM AND METHOD OF MANUFACTURING THE SAME

Weldable component of structural steel and method of manufacture

Steel sheet having excellent hydrogen induced cracking resistance and longitudinal strength uniformity, and manufacturing method therefor

High-strength structural steel material having excellent fatigue crack propagation inhibitory characteristics and manufacturing method therefor

Steel sheet

Method for manufacturing a high strength steel sheet and sheet obtained

High strength hot-rolled steel and method for manufacturing high strength hot-rolled steel

Hot stamped product, steel sheet for hot stamp, and manufacturing method thereof

High-strength galvanized steel sheet and method for manufacturing same

METHOD FOR MANUFACTURING A RAIL AND CORRESPONDING RAIL

Extremely high conductivity low cost steel

Use of a Q and P steel for producing a shaped component for high-wear applications

Low-temperature steel plate having excellent impact toughness, and method for manufacturing same

High-strength cold-rolled steel sheet

Method for the manufacture of a galvannealed steel sheet

Method for preventing cracking along the surface at the inner hole of a hollow shaft during horizontal water quenching

Method for the manufacture of a coated steel sheet

700MPa CLASS STEEL BAR HAVING EXCELLENT YIELD RATIO AND UNIFORM ELONGATION PROPERTY, AND METHOD FOR MANUFACTURING THE SAME

Steel sheet, plated steel sheet, method for producing hot-rolled steel sheet, method for producing cold-rolled full hard steel sheet, method for producing steel sheet, and method for producing plated steel sheet

HIGH STRENGTH STEELS, PROCESSES FOR MAKING SAME, AND MATERIALS RESULTING THEREFROM

Method for producing a high strength coated steel sheet having improved ductility and formability, and obtained coated steel sheet

High-strength steel material having excellent low-temperature strain aging impact properties and welding heat-affected zone impact properties and method for manufacturing same

Method of producing press-hardened and coated steel parts at a high productivity rate

Ultra high strength hot-rolled steel sheet having excellent ductility and method for manufacturing same

ULTRA-HIGH STRENGTH WEATHERING STEEL AND HIGH FRICTION ROLLING OF THE SAME

Steel material for welding steel pipe having excellent low-temperature toughness, steel material that has undergone weld heat treatment, and method for manufacturing same

Steel for coiled tubing with low yield ratio and ultra-high strength and preparation method thereof

COLD-ROLLED STEEL SHEET HAVING EXCELLENT BENDABILITY AND HOLE EXPANDABILITY AND METHOD FOR MANUFACTURING SAME

FROG FOR SWITCHES AND CROSSINGS

Hot-dip galvanized steel sheet

High-strength steel sheet and manufacturing method therefor

Steel sheet

Hot-dip galvanized steel sheet

Hot rolled steel sheet and method for manufacturing same

Steel wire and wire rod

Method for producing a high strength coated steel sheet having improved strength, formability and obtained sheet

TRACK PART AND METHOD FOR PRODUCING A TRACK PART

Drill bit for drilling and method for manufacturing same

Cold-rolled steel sheet with excellent formability, galvanized steel sheet, and manufacturing method thereof

Method for producing high-strength steel parts with improved ductility, and parts obtained by said method

High-strength steel sheet and method for producing same

High-strength galvanized steel sheet and method for producing the same

HIGH STRENGTH COLD-ROLLED STEEL SHEET HAVING EXCELLENT YIELD STRENGTH, DUCTILITY, AND HOLE EXPANDABILITY, HOT-DIP GALVANIZED STEEL SHEET, AND METHOD FOR PRODUCING SAME

Method for producing a high strength steel sheet having high ductility, formability and weldability, and obtained steel sheet

Method of manufacturing cam piece for continuously variable valve duration and cam piece manufactured therefrom

HIGH-STRENGTH GALVANIZED STEEL SHEET AND METHOD OF PRODUCING THE SAME

Hot press-formed part

Ultra high strength hot rolled steel sheet having low deviation of mechanical property and excellent surface quality, and method for manufacturing same

Steel sheet and manufacturing method therefor

Hot-dip galvanized steel sheet

Steel sheet for manufacturing press hardened parts, press hardened part having a combination of high strength and crash ductility, and manufacturing methods thereof

METHOD OF DETERMINING A COMPOSITION OF A STEEL ALLOY FOR USE IN A LOW-ALLOY HIGH-STRENGTH STEEL

Hot Rolled Precipitation Strengthened and Grain Refined High Strength Dual Phase Steel Sheet Possessing 600 MPa Minimum Tensile Strength and a Process Thereof

STEEL WIRE ROD, STEEL WIRE, AND PART

Ultra-thick steel material having excellent surface part NRL-DWT properties and method for manufacturing same

Cold-rolled steel sheet

STEEL SHEET AND METHOD OF PRODUCING THE SAME

Rolled wire rod for spring steel

Tempered and coated steel sheet having excellent formability and a method of manufacturing the same

HIGH-STRENGTH COLD-ROLLED STEEL SHEET, HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET, AND HIGH-STRENGTH HOT-DIP GALVANNEALED STEEL SHEET EXCELLENT IN FORMABILITY AND SHAPE FIXABILITY, AND METHODS FOR MANUFACTURING THEM

Method of manufacturing fuel rail for gasoline direct injection

HIGH-STRENGTH STEEL SHEET

HIGH STRENGTH MULTI-PHASE STEEL HAVING EXCELLENT BURRING PROPERTIES AT LOW TEMPERATURE, AND METHOD FOR PRODUCING SAME

High-strength cold rolled steel sheet and method for manufacturing the same

WIRE ROD

HIGH STRENGTH STEEL SHEET HAVING EXCELLENT DUCTILITY AND STRETCH FLANGEABILITY

High-strength cold-rolled steel sheet

Hot-dip galvanized steel plate with excellent bake hardenability and anti-aging property at room temperature

STEEL WIRE ROD AND MANUFACTURING METHOD OF STEEL WIRE ROD

Steel sheet

A METHOD FOR MANUFACTURING A THERMALLY TREATED STEEL SHEET

High strength cold rolled steel sheet and method of producing same

A METHOD FOR MANUFACTURING A THERMALLY TREATED STEEL SHEET

Cold rolled steel wire, method and reinforcement of flexible conduits

Hot rolled steel sheet

High-strength galvanized steel sheet and method for producing the same

Cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet

Steel sheet

Hot rolled steel sheet

HOT ROLLED STEEL SHEET, STEEL FORGED PART AND PRODUCTION METHOD THEREFOR

METHOD FOR PRODUCING A STRIP STEEL KNIFE, AND STRIP STEEL KNIFE FOR TOOLS

Steel sheet

Hot rolled steel product with ultra-high strength minimum 1100MPA and good elongation 21%

Hot press-formed member having excellent crack propagation resistance and ductility, and method for producing same

Spring and manufacture method thereof

Hot-rolled steel sheet for coiled tubing

Electric resistance welded steel tube for coiled tubing and method for manufacturing the same

High-hardness wear-resistant steel and method for manufacturing same

Ultra-thick steel material having excellent surface part NRL-DWT properties and method for manufacturing same

High-hardness wear-resistant steel and method for manufacturing same

TEMPERED MARTENSITIC STEEL HAVING LOW YIELD RATIO AND EXCELLLENT UNIFORM ELONGATION, AND MANUFACTURING METHOD THEREFOR

Ultra-high strength steel sheet having excellent bendability and manufacturing method therefor

Pressure vessel steel sheet having excellent PWHT resistance, and manufacturing method therefor

STEEL SHEET AND PROCESS FOR PRODUCING SAME

High-strength steel sheet and method for producing the same

HIGH STRENGTH COLD ROLLED STEEL SHEET FOR AUTOMOTIVE USE

Method of dynamical adjustment for manufacturing a thermally treated steel sheet

Method of producing a hot-rolled high-strength steel with excellent stretch-flange formability and edge fatigue performance

High-strength cold-rolled steel sheet and method of producing the same

High-strength steel sheet with excellent crashworthiness characteristics and formability and method of manufacturing the same

Tempered and coated steel sheet having excellent formability and a method of manufacturing the same

High-strength cold rolled steel sheet having high formability and a method of manufacturing thereof

Hot rolled flat steel product consisting of a complex-phase steel with a largely bainitic microstructure and method for manufacturing such a flat steel product

Method for manufacturing quenched molding, method for manufacturing hot press steel material, and hot press steel material

High-strength steel sheet with excellent crashworthiness characteristics and formability and method of manufacturing the same

Steel sheet

High strength, high toughness, heat-cracking resistant bainite steel wheel for rail transportation and manufacturing method thereof

Hot rolled steel plate for electric resistance welded steel pipe having excellent weldability, and manufacturing method thereof

Micro alloyed steel and method for producing said steel

Ultra high-strength air-hardening multiphase steel having excellent processing properties, and method for manufacturing a strip of said steel

Steel sheet and plated steel sheet

High friction rolling of thin metal strip

OIL WELL PIPE FOR EXPANDABLE TUBULAR

Pressure vessel steel having excellent hydrogen induced cracking resistance, and manufacturing method therefor

Medium-manganese steel product for low-temperature use and method for the production thereof

Cold-rolled high-strength steel having tensile strength of not less than 1500 MPA and excellent formability, and manufacturing method therefor

Method for making a high strength multiphase steel

Hot-rolled steel sheet for tailored rolled blank and tailored rolled blank

Ultrahigh-strength steel sheet having excellent yield ratio, and manufacturing method therefor

Steel sheet

Steel sheet and plated steel sheet

Steel sheet and plated steel sheet

High-strength steel sheet and production method therefor

Steel sheet and plated steel sheet

Steel for a tool holder

Steel sheet

Method for the in-line manufacturing of steel tube

Metal coated steel sheet, manufacturing method of hot-dip galvanized steel sheet, and manufacturing method of alloyed galvannealed steel sheet

Steel sheet coated with a metallic coating based on aluminum

HIGH-STRENGTH STEEL PLATE AND MANUFACTURING METHOD THEREOF

Hot-rolled steel sheet for heavy-wall, high-strength line pipe, welded steel pipe for heavy-wall, high-strength line pipe, and method for producing the welded steel pipe

Steel pipe or tube for pressure vessels, method of producing steel pipe or tube for pressure vessels, and composite pressure vessel liner

High-strength flat steel product

Steel sheet and method for producing the same

HIGH-STRENGTH STEEL SHEET AND PRODUCTION METHOD THEREFOR

High-strength cold rolled steel sheet and method for producing the same

Method for producing a shaped component from a medium-manganese flat steel product and such a component

Steel sheet and method for producing the same

980 MPa-grade hot-rolled ferritic bainite dual-phase steel and manufacturing method therefor

Cold-rolled high-strength steel plate having excellent phosphating performance and formability and manufacturing method therefor

Method of producing press-hardened and coated steel parts at a high productivity rate

Hot-rolled steel sheet

Composite pressure vessel liner, composite pressure vessel, and method for producing composite pressure vessel liner

HIGH-STRENGTH BAINITIC STEEL

High-strength steel sheet and method for producing same

Hot-rolled steel sheet and manufacturing method thereof

Method of producing press-hardened and coated steel parts at a high productivity rate

Economical plastic tooling cores for mold and die sets

Low cost lean production bainitic steel wheel for rail transit, and manufacturing method therefor

Steel sheet

Lightweight steel and steel sheet with enhanced elastic modulus, and manufacturing method thereof

A PRESS HARDENING METHOD

Steel sheet, plated steel sheet, method of production of hot-rolled steel sheet, method of production of cold-rolled full hard steel sheet, method of production of steel sheet, and method of production of plated steel sheet

FLAT STEEL PRODUCT AND METHOD FOR THE PRODUCTION THEREOF

Process of manufacturing a steel alloy for railway components

Method for joining steel rails with controlled weld heat input

High-strength steel plate for pressure vessel having excellent toughness after post weld heat treatment and manufacturing method thereof

High-strength steel having superior brittle crack arrestability, and production method therefor

High-strength steel sheet and method for manufacturing the same

Steel sheet and plated steel sheet, method for producing steel sheet, and method for producing plated steel sheet

HIGH STRENGTH STEEL SHEET AND MANUFACTURING METHOD THEREFOR

HIGH-STRENGTH THIN STEEL SHEET AND MANUFACTURING METHOD THEREFOR

HIGH-STRENGTH STEEL SHEET AND METHOD FOR MANUFACTURING SAME

Steel sheet, plated steel sheet, method of production of hot-rolled steel sheet, method of production of cold-rolled full hard steel sheet, method of production of steel sheet, and method of production of plated steel sheet

Steel material and oil-well steel pipe

High-strength hot-rolled steel sheet for electric resistance welded steel pipe and manufacturing method therefor

HIGH-STRENGTH GALVANIZED STEEL SHEET AND METHOD FOR PRODUCING THE SAME

B-pillar central beam and method for manufacturing

Steel material and oil-well steel pipe

LOW ALLOY HIGH STRENGTH SEAMLESS STEEL PIPE FOR OIL COUNTRY TUBULAR GOODS

Low alloy high strength seamless steel pipe for oil country tubular goods

Steel H-shape for low temperature service and manufacturing method therefor

High-strength galvanized steel sheet, high-strength member, and method for producing high-strength galvanized steel sheet

THERMALLY TREATED METALLIC MATERIALS AND RELATED METHODS

High-strength cold-rolled steel sheet

High-strength steel sheet for warm working and method for manufacturing the same

Steel plate for high-strength and high-toughness steel pipes and method for producing steel plate

High-strength steel sheet and method for producing the same

High-strength steel sheet and method for manufacturing the same

High-yield-ratio high-strength galvanized steel sheet and method for manufacturing the same

High strength steel sheet and method for producing the same

Heat treatment method and heat treatment device

STEEL MATERIAL HAVING EXCELLENT HYDROGEN-INDUCED CRACKING (HIC) RESISTANCE FOR PRESSURE VESSEL AND MANUFACTURING METHOD THEREFOR

HIGH STRENGTH FORGED STEEL AND LARGE FORGED COMPONENT

Heat treatment method and heat treatment device

High-strength steel sheet, high-strength galvanized steel sheet, method for manufacturing high-strength steel sheet, and method for manufacturing high-strength galvanized steel sheet

Steel sheet for tool and manufacturing method therefor

HIGH-STRENGTH PLATED STEEL PLATE FOR WELDED STRUCTURAL MEMBER, AND METHOD FOR PRODUCING THE SAME

Galvannealed steel sheet

Hot work tool steel

High-strength steel sheet and high-strength galvanized steel sheet

Method for producing a high strength steel sheet having improved ductility and formability, and obtained steel sheet

Method for producing a high strength steel sheet having improved strength and formability, and obtained high strength steel sheet

Method for producing a steel sheet having improved strength, ductility and formability

VEHICLE PART HAVING HIGH STRENGTH AND EXCELLENT DURABILITY, AND MANUFACTURING METHOD THEREFOR

Ultra-high strength steel sheet having excellent phosphatability and bendability

CASE HARDENING STEEL, CARBURIZED COMPONENT, AND MANUFACTURING METHOD OF CASE HARDENING STEEL

High strength galvannealed steel sheet and method of producing such steel sheet

LOW YIELD RATIO AND HIGH-STRENGTH STEEL HAVING EXCELLENT STRESS CORROSION CRACKING RESISTANCE AND LOW TEMPERATURE TOUGHNESS

High-strength hot-dip galvanized steel sheet having excellent surface quality and spot weldability

High strength cold-rolled steel sheet and hot-dip galvanized steel sheet having excellent hole expansion, ductility and surface treatment properties, and method for manufacturing same

STEEL PLATE HAVING EXCELLENT PWHT RESISTANCE FOR LOW-TEMPERATURE PRESSURE VESSEL AND METHOD FOR MANUFACTURING SAME

Pressure vessel steel plate having excellent post weld heat treatment resistance, and manufacturing method therefor

HIGH-STRENGTH STEEL MATERIAL HAVING EXCELLENT LOW-TEMPERATURE STRAIN AGING IMPACT PROPERTIES AND METHOD FOR MANUFACTURING SAME

High yield ratio type high-strength cold-rolled steel sheet and manufacturing method thereof

Material for high strength steel sheets, hot rolled material for high strength steel sheets, hot-rolled and annealed material for high strength steel sheets, high strength steel sheet, high strength hot-dip-coated steel sheet, high strength electroplated steel sheet, and method of manufacturing same

HIGH-STRENGTH STEEL HAVING EXCELLENT BRITTLE CRACK ARRESTABILITY AND WELDING PART BRITTLE CRACK INITIATION RESISTANCE, AND PRODUCTION METHOD THEREFOR

Thick steel plate having excellent low-temperature toughness and hydrogen-induced cracking resistance, and method for manufacturing same

HOT ROLLED BAR OR HOT ROLLED WIRE ROD, COMPONENT, AND MANUFACTURING METHOD OF HOT ROLLED BAR OR HOT ROLLED WIRE ROD

ULTRA-HIGH STRENGTH STEEL SHEET HAVING EXCELLENT PHOSPHATABILITY AND HOLE EXPANDABILITY AND METHOD FOR MANUFACTURING SAME

Rolled Rod for Cold-Forged Thermally Refined Article

High-strength air-hardening multiphase steel having excellent processing properties, and method for manufacturing a strip of said steel

Engineering Steel with a Bainitic Structure, Forged Parts Produced Therefrom and Method for Producing a Forged Part

Thick steel plate for structural pipes or tubes, method of producing thick steel plate for structural pipes or tubes, and structural pipes and tubes

STEEL SHEET FOR HOT PRESSING USE, PRESS-FORMED PRODUCT, AND METHOD FOR MANUFACTURING PRESS-FORMED PRODUCT

Hot rolled steel sheet and method for manufacturing the same

Prehardened steel material, mold, and mold component

Micro-alloyed high-strength multi-phase steel containing silicon and having a minimum tensile strength of 750 MPA and improved properties and method for producing a strip from said steel

Galvannealed steel sheet and method for producing the same

Steel plate for structural pipes or tubes, method of producing steel plate for structural pipes or tubes, and structural pipes and tubes

STEEL PLATE FOR STRUCTURAL PIPES OR TUBES, METHOD OF PRODUCING STEEL PLATE FOR STRUCTURAL PIPES OR TUBES, AND STRUCTURAL PIPES AND TUBES

ONLINE-CONTROL COOLING PROCESS FOR SEAMLESS STEEL TUBE FOR EFFECTIVELY REFINING GRAINS AND THE METHOD FOR MANUFACTURING THEREOF

Method for manufacturing bainite high-strength seamless steel tube, and bainite high-strength seamless steel tube

Steel sheet coated with a metallic coating based on aluminum and comprising titanium

Seamless steel tube with high strength and toughness and manufacturing method therefor

Plated steel plate and manufacturing method thereof

Process for on-line quenching of seamless steel tube using residual heat and manufacturing method

Hot-rolled high-strength roll-formable steel sheet with excellent stretch-flange formability and a method of producing said steel

Good fatigue- and crack growth-resistant steel plate and manufacturing method therefor

METHOD OF PRODUCING A TOOL STEEL

600 MPa yield strength-graded, high-stretchability hot-dip aluminum-zinc and color-coated steel plate and manufacturing method therefor

500 MPA yield strength-graded, high-stretchability hot-dip aluminum-zinc and color-coated steel plate and manufacturing method therefore

AGE-HARDENABLE STEEL, AND METHOD FOR MANUFACTURING COMPONENTS USING AGE-HARDENABLE STEEL

STEEL SHEET

HIGH-HARDNESS STEEL SHEET, AND MANUFACTURING METHOD THEREOF

High-strength hot-rolled steel sheet and method for manufacturing the same

Steel sheet

HIGH STRENGTH HOT DIP GALVANISED STEEL STRIP

Cold-rolled steel sheet, coated steel sheet, method for manufacturing cold-rolled steel sheet, and method for manufacturing coated steel sheet

STEEL MATERIAL FOR COMPOSITE PRESSURE VESSEL LINER, STEEL PIPE OR TUBE FOR COMPOSITE PRESSURE VESSEL LINER, AND METHOD OF MANUFACTURING STEEL PIPE OR TUBE FOR COMPOSITE PRESSURE VESSEL LINER

Rolling element bearing having bainite microstructure

HIGH-TENSILE STEEL CONTAINING MANGANESE, USE OF SAID STEEL FOR FLEXIBLY-ROLLED SHEET-PRODUCTS, AND PRODUCTION METHOD AND ASSOCIATED STEEL SHEET-PRODUCT

Method for the manufacture of a hardened part which does not have LME issues

High-strength screw including an unhardened thread end

Method for the manufacture of a phosphatable part starting from a steel sheet coated with a metallic coating based on aluminum

High-strength PC steel wire

Steel sheet with strain induced transformation type composite structure and method of manufacturing same

METHOD OF PRODUCING A HOT STRIP OF A BAINITIC MULTI-PHASE STEEL HAVING A ZN-MG-AL COATING, AND A CORRESPONDING HOT STRIP

Steel sheet, hot-dip galvanized steel sheet, galvanized steel sheet, and manufacturing methods therefor

Steel sheet, hot-dip galvanized steel sheet, galvannealed steel sheet, and manufacturing methods therefor

Steel for press hardening and press hardened part manufactured from such steel

High-strength cold-rolled steel sheet, high-strength hot-dip galvanized steel sheet and high-strength galvannealed steel sheet

HIGH-STRENGTH THIN STEEL SHEET AND METHOD OF PRODUCING THE SAME

Steel pipe for line pipe and method of manufacturing the same

High-toughness seamless steel tube for automobile safety airbag and manufacturing method therefor

High strength steel and production method

High-strength cold-rolled steel sheet, high-strength hot-dip galvanized steel sheet, and high-strength hot-dip galvannealed steel sheet having excellent ductility, stretch-flangeability, and weldability

Steel pipe for fuel injection pipe and method for producing the same

METHOD FOR MANUFACTURING HIGH-STRENGTH AND DUCTILE TRIP STEEL

Hot-press molding method and hot-press molded product

Method of manufacture of multiphase, hot-rolled ultra-high strength steel

Method of manufacture of multiphase, cold-rolled ultra-high strength steel

BAINITIC STEEL MATERIALS AND METHODS OF MAKING SUCH MATERIALS

HOT ROLLED STEEL SHEET AND METHOD OF MANUFACTURING SAME

STEEL FOR NITROCARBURIZING AND NITROCARBURIZED COMPONENT, AND METHODS OF PRODUCING SAME

THICK STEEL PLATE FOR STRUCTURAL PIPES OR TUBES, METHOD OF PRODUCING THICK STEEL PLATE FOR STRUCTURAL PIPES OR TUBES, AND STRUCTURAL PIPES AND TUBES