Jfe Steel Corporation

Fuji Jukogyo Kabushiki Kaisha

Subaru Corporation

Mitsubishi Paper Mills Limited

Riso Kagaku Corporation

Tokyo University of Agriculture and Technology

Mitsumi Electric Company Ltd.

Nkk Corporation

Kawasaki Jukogyo Kabushiki Kaisha

Kobe Steel, Ltd.

Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Dainippon Ink and Chemicals, Incorporated

Combi Co., Ltd.

Astellas Pharma Gmbh

Thyssenkrupp Steel Europe Ag

Hiroshi Matsuda

Rinsei Ikeda

Chikaumi Sawanishi

Katsutoshi Takashima

Koichi Taniguchi

Yoshiyasu Kawasaki

Yasuaki Okita

Kazuhiro Seto

Yoshimasa Funakawa

Takeshi Yokota

Yasushi Tanaka

Hiroi Yamaguchi

Yasuyuki Hayakawa

Yoichi Makimizu

Yukihiro Shingaki

Katsuya Hoshino

Takashi Kawano

Takashi Terashima

Yasunobu Nagataki

Hideyuki Takahashi

Jun Watanabe

Yoshihiko Ono

Kohei Hasegawa

Kaneharu Okuda

Takashi Kobayashi

Takeshi Fujita

Masahiro Saito

Shinjiro Kaneko

Yoshihiro Hosoya

Touru Noda

Shusaku Takagi

Shinroku Nakao

Yoshiyasu Ishii

Kazuhiko Sato

Junji Sato

Tatsuya Nakagaito

Yuji Yamasaki

Minoru Tanaka

Yoshitsugu Suzuki

Keiichi Yamamoto

Toshito Takamiya

Nobuyuki Nakamura

Akio Kobayashi

Reiichi Suzuki

Saiji Matsuoka

Satoru Ando

Yusuke Fushiwaki

Norio Seki

Akira Matsuda

Ryoji Ohashi

Kenji Kawamura

Yoshiharu Sugimoto

Takako Yamashita

Shunsuke Yamamoto

Tomomi Kanazawa

Yusuke Okumura

Muneo Matsushita

Masaki Koba

Yuiko Wakisaka

Minoru Iida

Toshiaki Naruke

Takehisa Tsukada

Masanori Nagoshi

Jun Urasaki

Mai Aoyama

Masaya Morita

Hiromi Yoshitomi

Fusato Kitano

Koji Idei

Toru Inazumi

Yoshie Obata

Moriaki Ono

Kazunori Tahara

Hiroo Kaji

Masanori Takenaka

Takuya Fukuda

Shimpei Yoshioka

Yoshitaka Muramatsu

Manabu Hashimoto

Yuma Honda

Thomas Heller

Kenji Oi

Tetsuya Ashida

Takayuki Futatsuka

Taro Kizu

Yohei Enta

Hiroshi Ozawa

Mitsuo Kase

Junya Okamura

Toshihiro Shigematsu

Brigitte Hammer

Masayuki Tsubaki

Yoshiaki Murakami

Shunsuke Takahashi

Hiroshi Nagata

Minoru Miyata

Sachiko Suzuki

Ichiro Muramatsu

Yoshiyuki Tenda

Masahiro Takeda

Disclosed is a galvannealed steel sheet including: a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet; and a galvannealed layer formed on the Fe-based electroplating layer, in which in an intensity profile measured by glow discharge optical emission spectrometry, I/Iis 0.30 or more, and an average value of C concentration in a region ranging from 10 μm to 20 μm in the thickness direction from the interface between the galvannealed layer and the Fe-based electroplating layer towards the Fe-based electroplating layer is 0.10 mass % or less.

Galvannealed steel sheet, electrodeposition-coated steel sheet, automotive part, method of producing electrodeposition-coated steel sheet, and method of producing galvannealed steel sheet

Disclosed is an Fe-based electroplated steel sheet including: a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of 5.0 g/mor more, in which in an intensity profile measured by glow discharge optical emission spectrometry, a peak of emission intensity at wavelengths indicating Si is detected within a range from a surface of the Fe-based electroplating layer to more than 0.2 μm in a thickness direction and not more than a thickness of the Fe-based electroplating layer, and an average value of C concentration in a region ranging from 10 μm to 20 μm in the thickness direction from the surface of the Fe-based electroplating layer is 0.10 mass % or less.

Fe-based electroplated steel sheet, electrodeposition-coated steel sheet, automotive part, method of producing electrodeposition-coated steel sheet, and method of producing Fe-based electroplated steel sheet

Provided is a resistance spot welding method wherein main current passage includes two or more electrode force application steps including a first electrode force application step and a second electrode force application step following the first electrode force application step, an electrode force Fin the first electrode force application step and an electrode force Fin the second electrode force application step in the main current passage satisfy a relationship F>F, and an electrode force switching point Tfrom the first electrode force application step to the second electrode force application step in the main current passage is set to satisfy predetermined relational formulas.

Resistance spot welding method and weld member production method

Provided is a resistance spot welding method wherein main current passage includes two or more electrode force application steps including a first electrode force application step and a second electrode force application step following the first electrode force application step, an electrode force Fin the first electrode force application step and an electrode force Fin the second electrode force application step in the main current passage satisfy a relationship F<F, and an electrode force switching point Tfrom the first electrode force application step to the second electrode force application step in the main current passage is set to satisfy predetermined relational formulas.

Provided is a friction stir spot welded joint having high cross tensile strength even in the case where a steel sheet having a soft surface layer is used as a material to be welded. An annular groove is formed on an upper surface of an upper sheet out of overlapping steel sheets, and a shape and hardness of a welded portion are appropriately controlled simultaneously.

Friction stir spot welded joint and production method therefor, and friction stir spot welding method

A friction joining element for mechanically joining a sheet set prepared by stacking two or more metal sheets including a high strength steel sheet as an upper sheet. The friction joining element includes a mandrel having an overall length adjusted to be equal to or less than the total thickness of the sheet set, and a collar disposed at an upper portion of the mandrel. The friction joining element has a screw thread on a side surface of a head-side portion of the mandrel.

Friction joining element

To provide a steel sheet with excellent resistance to cracking in resistance welding at a welded portion. Disclosed is a galvanized steel sheet including: a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of 5.0 g/mor more; and a galvanized layer formed on the Fe-based electroplating layer, in which in an intensity profile measured by glow discharge optical emission spectrometry, I/Iis 0.50 or more, and an average value of C concentration in a region ranging from 10 μm to 20 μm from an interface between the galvanized layer and the Fe-based electroplating layer towards the Fe-based electroplating layer is 0.10 mass % or less.

Galvanized steel sheet, electrodeposition-coated steel sheet, automotive part, method of producing electrodeposition-coated steel sheet, and method of producing galvanized steel sheet

A resistance spot weld, a resistance spot welding method, a resistance spot welded joint, and a method for manufacturing the resistance spot welded joint. In the resistance spot weld, at least one of steel sheets is a high-strength steel sheet having a prescribed chemical composition. In at least one of a nugget edge region corresponding to a faying interface, the nugget edge region has a metal microstructure including tempered martensite as a main phase. The hardness Hv of the nugget edge region and the hardness Hmw of martensite in the nugget as a whole satisfy formula (4). In at least one of a strong HAZ region corresponding to the faying interface, the hardness Hh of the strong HAZ region and the hardness Hmh of martensite in a prescribed steel sheet satisfy formula (8).

Resistance spot weld, resistance spot welding method, resistance spot welded joint, and method for manufacturing resistance spot welded joint

Provided is a resistance spot welding method by which a desired nugget diameter can be stably obtained without expulsion even when the effect of a disturbance is significant. An electrode force Fof a main current passage after an intermediate welding time Tis set based on an average value or time integration value Rof a resistance between electrodes from the start of main current passage to the intermediate welding time T.

Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

Provided is an alloyed galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The alloyed galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface exceeding 20.0 g/m, and an alloyed galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

Alloyed galvanized steel sheet, electrodeposition-coated steel sheet, automotive part, method of producing electrodeposition-coated steel sheet, and method of producing alloyed galvanized steel sheet

A welding process used in a method of manufacturing a steel sheet assembly includes spot welding steel sheets performed for a heat time of 0.08 seconds or more using a convex electrode with a tip radius of curvature of 20 mm or more or a flat electrode such that the weld force F (kN) for initial 0.03 seconds of the heat time satisfies formula: F<0.00125×(1+0.75×t)+3 where TS (MPa) denotes an average strength of the steel sheets and represents a weighted mean value of a thickness of each of the steel sheets, and t(mm) denotes a total thickness of the steel sheets (the sum of the thicknesses of the steel sheets).

Steel sheet assembly, method of manufacturing steel sheet assembly, and spot welding process

Disclosed are rotating tools for double-sided friction stir welding that are applied to double-sided friction stir welding, which is a technique for welding two metal plates by rotating a pair of rotating tools, which oppose each other, in opposite directions, a double-sided friction stir welding apparatus that uses the rotating tools, and a double-sided friction stir welding method. A pair of rotating tools for double-sided friction stir welding that are used in double-sided friction stir welding, which is a technique for welding metal plates by using a pair of rotating tools that are each disposed on one of first and second surfaces of an unwelded portion of the metal plates such that the rotating tools rotate in opposite directions, include end portions each of which is formed in a circular and planar shape. The end portions are each made of a material harder than the metal plates.

Rotating tool for double-sided friction stir welding, double-sided friction stir welding apparatus, and double-sided friction stir welding method

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in main current passage in the actual welding, adaptive control welding is performed, and in subsequent current passage in the actual welding, current passage is performed by constant current control with a current determined based on an electrical property between electrodes in each of main current passage in the test welding and the main current passage in the actual welding.

A gas-shielded arc welding method includes welding a steel plate having a tensile strength of 780 MPa or more while feeding a consumable electrode via a welding torch and flowing a shielding gas. The consumable electrode includes, in mass %, C: 0 to 0.20%, Si: 0 to 0.50%, Mn: 0 to 0.50%, Cr: 1.00% to 9.00%, S: 0.0020% to 0.0600%, and Ni: 0 to 0.50%. The shielding gas includes, in vol. %, at least one of COand O: 1% to 15% in total, with the remainder being Ar and unavoidable impurities. Welding is performed under the condition satisfying the relationship of 1≤{−0.05×[CO+O]}+[Cr]≤8.3, and [Cr] represents the content of Cr in the consumable electrode, and [CO+O] represents a total content of at least one of COand Oin the shielding gas.

Gas-shielded arc welding method and method for manufacturing welded structure

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Tokyo, Japan

Hiroshi Matsuda