Jfe Steel Corporation

Nkk Corporation

Satoshi Kinoshiro

Kyoko Fujimoto

Masao Inose

Toshiyuki Ito

Tomoharu Ishida

Katsumi Yamada

Yoshihito Iwata

Ryo Kawabata

Tadashi Mochizuki

Yohichi Ishibashi

Akiko Sakashita

Takanori Akiyoshi

Toshiro Ishige

Kaoru Sato

Takeshi Yokota

Koichi Nakagawa

Yuji Tanaka

Nobuyuki Nakamura

Kazuhiro Seto

Yoshihiko Kawai

Katsumi Nakajima

Hisato Noro

Tetsuya Mega

Kazutoshi Hanada

Hiroaki Miyahara

Yoichi Nimura

A method for desulfurizing molten steel comprising taking a sample out from molten steel after tapping from a converter or during secondary refining and analyzing the sample rapidly with high accuracy by a method comprising a high frequency induction heating step wherein the sample is combusted and oxidized under the high frequency induction heating in an oxygen atmosphere having an oxygen purity of 99.5 vol % or more to convert S in the sample into SOand an analyzing step wherein SO-containing gas produced in the high frequency induction heating step is analyzed through an ultraviolet fluorescence method to quantify S concentration of the sample.

Molten steel desulfurization method, molten steel secondary refining method, and molten steel manufacturing method

Provided are a method for analyzing nitrogen in a metal sample, an apparatus for analyzing nitrogen in a metal sample, a method for adjusting nitrogen concentration in molten steel, and a method for manufacturing steel. The method includes: a melting process in which a metal sample containing a nitrogen component is melted in an argon gas atmosphere by performing impulse heating to gasify the nitrogen component; and an analyzing process in which nitrogen content in the metal sample is determined by analyzing nitrogen gas generated in the melting process and the argon gas by using a gas discharge optical emission method. By analyzing the nitrogen concentration of a sample taken from molten steel by using the analysis method described above, and by determining treatment conditions for adjusting nitrogen concentration on the basis of the nitrogen analysis value derived by the analysis, nitrogen concentration in molten steel is adjusted.

Method for analyzing nitrogen in metal sample, apparatus for analyzing nitrogen in metal sample, method for adjusting nitrogen concentration in molten steel, and method for manufacturing steel

A high-strength steel sheet includes a composition containing, in mass percent, 0.08% to 0.20% of carbon, 0.2% to 1.0% of silicon, 0.5% to 2.5% of manganese, 0.04% or less of phosphorus, 0.005% or less of sulfur, 0.05% or less of aluminum, 0.07% to 0.20% of titanium, and 0.20% to 0.80% of vanadium, the balance being iron and incidental impurities.

High strength steel sheet and method for manufacturing the same

In a method for desulfurizing hot metal by analyzing S concentration of a sample taken out from the hot metal, the S concentration is analyzed rapidly and precisely by a method comprising a high frequency induction heating step of oxidizing the sample under a high frequency induction heating in a pure oxygen atmosphere to convert S in the hot metal to SOand an analysis step of analyzing SO-containing gas generated in the high frequency induction heating step through an ultraviolet fluorescence method to quantify S concentration in the sample, whereby S concentration after the desulfurization is controlled precisely and hence fault of S concentration is prevented but also the increase of the cost due to the excessive addition of a desulfurization agent and step disruption at steel-making step are prevented.

Method for desulfurizing hot metal

An analyzing method which enables highly precise and rapid quantitative analysis of sulfur contained in a metal sample, includes: combusting a metal sample containing a sulfur component under pure oxygen gas atmosphere to oxidize the sulfur component into sulfur dioxide; and quantitatively analyzing sulfur in the metal sample through analysis, according to a UV fluorescence method, of a sulfur dioxide containing gas containing the sulfur dioxide generated by combustion of the metal sample.

Method and device for analyzing sulfur in metal sample

A method for analyzing a metal material includes electrolyzing a metal sample in an electrolytic solution, immersing a remaining portion of the metal sample taken out of the electrolytic solution in a dispersible solution to separate at least one substance selected from the group consisting of precipitates and inclusions attached to the remaining portion of the metal sample, filtering the dispersible solution containing the at least one separated substance through filters having straight pores and a porosity of 4% or more to obtain residues trapped on the filters and filtrates, and analyzing at least one of the residues and the filtrates.

Method for analyzing metal material

A method for analyzing a metallic material includes the steps of electrolyzing a metal sample in an electrolyte; removing the electrolyzed metal sample from the electrolyte; immersing the metal sample removed from the electrolyte into a dispersive solution that is different from the electrolyte to separate at least one selected from the group consisting of a precipitate and an inclusion deposited on the metal sample; and analyzing the at least one selected from the group consisting of a precipitate and an inclusion extracted into the dispersive solution.

Method for analysis of metal inclusions in steels by partial electrolysis

A method for analyzing a metal specimen includes an electrolysis step of electrolyzing a metal specimen containing a reference element and a target element in an electrolytic solution, a sampling step of sampling a portion of the electrolytic solution, an analysis step of analyzing the sampled electrolytic solution, a concentration ratio-calculating step of calculating the concentration ratio of the target element to the reference element in the electrolytic solution on the basis of the analysis results, and a content-calculating step of calculating the content of the target element present in the form of a solid solution by multiplying the content of the reference element in the metal specimen by the obtained concentration ratio.

Method for analyzing metal specimen

A method for analyzing steel which comprises: grinding an analysis area of a steel ingot; sealing the analysis area with a sealing section of a cell for generating fine particles; again grinding the analysis area, while an argon gas is introduced into the cell; irradiating a pulsed laser beam of 10.sup.8 W/cm.sup.2 or more onto the analysis area at an irradiating spot of at least 1 mm.sup.2 to generate the fine particles; moving the irradiating spot; and transferring the generated fine particles by the argon gas to a plasma emission analysis for analysis. A further method for analyzing steel comprises: solidifying a molten steel sample, forming a red-hot sample; putting the sample into a sample holding section of a sample chamber under a purified argon gas atmosphere, the sample holding section having an inner curved surface the same as a curved surface of the sample; irradiating a pulsed laser onto the sample to remove a sample surface layer of 25 .mu.m or more of the sample and to generate fine particles from the sample; and exciting the fine particles by a plasma emission analyzer to analyze the composition of the fine particles.

Method for analyzing steel and apparatus therefor

A method for analyzing solid sample comprises the steps of: introducing an inert carrier gas into a cell; a preliminary treatment step of irradiating laser beam to a sample surface of the solid sample in the inert carrier gas, the laser beam having a pulse half width of 0.001 .mu.sec or more, a pulse energy density of 0.001 GW/cm.sup.2 or more, and a frequency of 100 Hz or more; generating fine particles in the inert carrier gas on a condition that a rate of fine particles generation, V (.mu.g/sec), and selection ratio, S, satisfy the following equations, the selection ratio being a retio of a concentration of a target element for analysis within the fine particles to a concentration of the target element for analysis within the solid sample;

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Kawasaki, Japan

Satoshi Kinoshiro