Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Nippon Steel & Sumitomo Metal Corportion

Hitomi Nishibata

Masanori Yasuyama

Manabu Fukumoto

Hiroyuki Takahashi

Yoshiaki Nakazawa

Toshiya Suzuki

Masahiro Nakata

Yasuo Takahashi

Yasunobu Miyazaki

Hiroki Fujimoto

Tohru Okada

Seiji Furusako

Masahito Tasaka

Tasuku Zeniya

Kazuhito Imai

The spot welding method of the present invention has steps of preliminary conduction, first conduction, second conduction, and third conduction:

Spot welding method

A brazed joint having excellent tensile strength (TSS and CTS) and a method of production of the same are provided. A sheet combinationcomprised of steel sheetsbetween which a brazing filler metalis clamped is heated at a temperature of the Ac3 point of the steel sheet (matrix material) or more. The Ar3 point of the regions near the brazing filler metal at the steel sheets is made higher than the Ar3 point of the steel sheets (matrix material), then the quenching start temperature X is made a temperature of the Ar3 point of the steel sheet (matrix material) or less and hot stamping is performed to produce a brazed joint.

Method of production of brazed joint and such a brazed joint

A overlapped bodycomprising steel platesandand satisfying (TS&#xd7;t+TS&#xd7;t)/(t+t)&#x2265;440 is energized while being sandwiched and pressed by a pair of electrodesandto form a molten poolat a steel plate interfaceand thereby to join the steel platesand. TSrepresents the tensile strength (MPa) of the steel plate, trepresents the thickness (mm) of the steel plateTSrepresents the tensile strength (MPa) of the steel plate, and trepresents the thickness (mm) of the steel plate. An energization pointis formed at the steel plate interface, and spot welding is performed such that the molten poolis formed at a position at a horizontal distance W of 20 mm or less from the energization point.

Resistance spot welding method and welded structure

An overlapped bodyincludes at least three steel platesandand in which at least one steel plate interfacehas a contact resistance different from the contact resistance of another steel plate interface. A molten pool is formed at the steel plate interfaces so as to join the steel platesand, and an energization pointis formed at the steel plate interfacehaving the largest contact resistance. Initial spot welding is performed under a condition in which a branch current is generated in the energization pointso as to form the molten pool. By doing so, it makes it difficult to generate the expulsion and surface flash at the steel plate interface where resistive heating is large and form the molten pool having a sufficiently large size at the steel plate interface where resistive heating is small.

A formed member is provided which can be manufactured at a low cost, which has excellent dimensional accuracy, which has excellent axial crushing properties and three-point bending properties, which has excellent bending stiffness and torsional stiffness, and which is suitable for use in a component of an automobile. The formed member () has a reinforcing member () which is joined by a weld () provided on a ridge portion (). It is manufactured by joining a flat sheet blank and a flat sheet reinforcing member () by a weld () and performing bending so that the weld () becomes a ridge portion ().

Formed member and manufacturing method thereof

The present invention is a friction welding method for friction welding of metal members characterized by starting friction welding in a state inserting an insert material between surfaces of the metal members facing each other, wherein the insert material consists of a metal having a melting point (centigrade temperature) of 60 to 80% of the melting point (centigrade temperature) of the metal members, melting the insert material, and pushing the melted insert material out from between the pair of metal members. Due to this, the adverse effects due to high temperature heating like in the past are eliminated while a quality of joint equal to or better than the past is obtained in a short time period.

Friction welding method

A galvanized steel sheet for hot forming, the galvanized steel sheet including a galvanized film provided on a surface of a steel sheet,

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Tokyo, Japan

Hitomi Nishibata