Nisshin Steel Co., Ltd.

Hiroshi Fujimoto

Katsuhisa Miyakusu

Takashi Igawa

Satoshi Suzuki

Teruo Tanaka

Yoshihiro Uematsu

Naoto Hiramatsu

Masayuki Kinugasa

Seiichi Isozaki

Yasutoshi Hideshima

Kouki Tomimura

Kazuo Hoshino

Naoki Hirakawa

Akira Sakakura

Kenichi Morimoto

Chizui Toyokihara

A stainless steel material having compositions which contain on the basis of percent by mass, C from 0.04 to 0.12%, Ni from 0 (including a case of no addition) to 5.0%, Cr from 12.0 to 17.0%, N from 0.0 to 0.10%, Si from 0.2 to 2.0%, Mn at 2.0% or less, Cu from 0.0 to 2.0%, P at 0.06% or less, S at 0.006% or less, with residue being Fe and unavoidable impurities. Further, a parent phase has any one of a single phase structure of ferrite phase or martensite phase and a diploid phase structure of ferrite phase and martensite phase. An end of the base material is melt-welded as a joint to form a pipe. The parent phase is provided with carbide uniformly separated at grain boundaries and within grains, with a dissolved amount of C being 0.03% by mass or less.

High-strength stainless steel pipe

Provided is a high-strength stainless steel material having less deterioration in mechanical strength and improved workability, particularly bending workability compared with conventional steel materials. The high-strength stainless steel material of the present invention has a specific composition, has a metal microstructure composed of two phases, that is a ferrite phase and a martensite phase, has a &#x3b3;max of from 50 to 85, the &#x3b3;being represented by the following equation (1):&#x3b3;=420W+470W+23W+7W&#x2212;11.5W&#x2212;11.5W+189&#x2003;&#x2003;(1)wherein, W, W, W, W, W, and W; represent contents (unit: mass %) of C, N, Ni, Mn, Cr, and Si relative to the total mass of the stainless steel material, respectively; and has a difference of 300 HV or less in hardness between the ferrite phase and the martensite phase.

High-strength stainless steel material and production process of the same

An austenitic stainless steel comprising (C+&#xbd;N) up to 0.060 mass %, Si up to 1.0 mass %, Mn up to 5 mass %, S up to 0.003 mass %, S/Mn ratio up to 0.003, 15&#x2013;20 mass % Cr, 5&#x2013;12 mass % Ni, Cu up to 5 mass %, 0&#x2013;3.0 mass % Mo and the balance being Fe except inevitable impurities under the condition that a value Md(representing a ratio of a strain-induced martensite) defined by the under-mentioned formula is controlled within a range of &#x2212;60 to &#x2212;10. Hardness increase of the steel sheet after being cold-rolled is preferably 20% or more as Vickers hardness. A metallurgical structure of the steel sheet is preferably adjusted to grain size number of #8 to #11 in a finish annealed state. The steel sheet is blanked with high dimensional accuracy, and a die life is also prolonged.Md=551&#x2212;462(C+N)&#x2212;9.2Si&#x2212;29(Ni+Cu)&#x2212;8.1Mn&#x2212;13.7Cr&#x2212;18.5Mo.

Austenitic stainless steel excellent in fine blankability

A high-strength austenitic stainless steel strip exhibiting excellent flatness with Vickers hardness of 400 or more has the composition comprising: C up to 0.20 mass %, Si up to 4.0 mass %, Mn up to 5.0 mass %, 4.0-12.0 mass % Ni, 12.0-20.0 mass % Cr, Mo up to 5.0 mass %, N up to 0.15 mass % and the balance being Fe except inevitable impurities having a value Md(N) in a range of 0-125 defined by the formula Md(N)&equals;580-520C-2Si-16Mn-16Cr-23Ni-26Cu-300N-10Mo. The material has a dual-phase structure of austenite and martensite involving a reverse-transformed austenite at a ratio of 3 vol. % or more. The material is manufactured by solution-heating a steel strip having the above composition, cold-rolling the steel strip to generate a deformation-induced martensite, and then re-heating at 500-700&deg; C. to induce a phase reversion from martensite to at least 3 vol. % austenite. The reversion effectively flattens the steel strip.

High-strength austenitic stainless steel strip having excellent flatness and method of manufacturing same

A high strength chromium containing steel sheet having a tensile strength of at least 40 kgf/mm.sup.2, and excellent in corrosion resistance and workability, comprising, by weight, C:up to 0.030%, Si:up to 2.30%, Mn:up to 3.0%, P:more than 0.0005% and not more than 0.150%, S:up to 0.010%, Ni:up to 2.0%, Cu:more than 0% and not more than 2.0%, Cr:not less than 5.0% and less than 10.0%, N:up to 0.030%, V:not less than 0.01% and not more than 0.10%, and optionally at least one of 0.01 to 0.30% of Ti, 0.01 to 0.30% of Nb, 0.01 to 0.30% of Zr, 0.01 to 0.20% of Al and 0.0002 to 0.0200% of B, the amounts of Si, Mn, P, Ni and Cu being adjusted so that the relation:Si+Mn+10P+Ni+Cu&gt;1.0% may be satisfied, the balance being iron and unavoidable impurities.

Chromium containing high strength steel sheet excellent in corrosion

A chromium containing steel sheet excellent in corrosion resistance and workability, comprising, by weight, C:up to 0.030%, Si:up to 0.5%, Mn:up to 0.5%, P:up to 0.040%, S:up to 0.010%, Ni:up to 0.3%, Cu:up to 0.3%, Cr: not less than 5.0% and less than 11.0%, N:up to 0.030%, V:not less than 0.01% and not more than 0.10%, and optionally at least one of 0.01 to 0.30% of Ti, 0.01 to 0.30% of Nb, 0.01 to 0.30% of Zr, 0.01 to 0.20% of Al and 0.0002 to 0.0200% of B, the amounts of Si, Mn, P, Ni and Cu being adjusted so that the relation:Si+Mn+10P+Ni+Cu.ltoreq.1.0% may be satisfied, the balance being iron and unavoidable impurities.

Chromium containing steel sheet excellent in corrosion resistance and

Process for producing high strength stainless steel of duplex structure

Process for producing steel strip of duplex structure wherein cold rolled strip of chromium stainless steel comprising, in addition to Fe, 10.0% to 20.0% of Cr, to 0.10% C, to 0.12% of N, the (C+N) being 0.01% to 0.20%, to 2.0% of Si, to 4.0% of Mn to 4.0% of Ni and to 4.0% of Cu, the {Ni+(Mn+Cu)/3} being not less than 0.5% but not more than 5.0%, is continuously passed through a heating zone where it is heated to form a two-phase of ferrite and austenite and the heated strip is cooled at a cooling rate sufficient to transform the austenite to martensite. The product has high strength and elongation reduced plane anisotropy and hardness of at least HV 200.

Process for the production of a strip of a chromium stainless steel of a

Process for producing steel strip of duplex structure wherein cold rolled strip of chromiun stainless steel comprising, in addition to Fe, 10.0% to 20.0% of Cr, to 0.15% of C, to 0.12% of N, the (C+N) being 0.02% to 0.20%, to 2.0% of Si, to 1.0% of Mn and to 0.6% of Ni, is continuously passed through a heating zone where it is heated to form a two-phase of ferrite and austenite and the heated strip is cooled at a cooling rate sufficient to transform the austenite to martensite. The product has high strength and elongation reduced plane anisotropy and hardness of at least HV 200.

A process for the production of an electrical steel sheet having the ideal (100) [001] cube texture of iron of iron alloy, comprising cold rolling a sheet of a single crystal or large grained crystals of iron or iron alloy, in which said single crystal is or a majority of said large grained crystals are oriented so that the pole of the {114} plane may form an angle not greater than 15.degree. with the normal direction of the plane of the sheet, and the &lt;401&gt; direction may form an angle of not greater than 15.degree. with a single direction in the plane of the sheet, in said single direction at a rolling reduction of at least 40%, and annealing the rolled sheet to form a primary recrystallization texture of fine grains of an average grain size of not larger than 5 mm under conditions preventing the occurrence of secondary recrystallization.

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Yamaguchi, Japan

Hiroshi Fujimoto