National Institute for Materials Science

Neturen Co., Ltd.

Nissan Motor Company Limited

Munehisa Hatta

Kazuhiro Kawasaki

Takahiko Kanai

Kotobu Nagai

Masao Hayakawa

Fumiaki Ikuta

Takehiko Itagaki

Eizaburou Nakanishi

Tsuyoshi Yoshida

Eizaburo Nakanishi

Masayuki Miyake

Takehito Itagaki

A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment sandwiches metallic materials with a pair of electrodes, and heats different regions of the metallic materials by energization, with the pair of electrodes maintained at the same position with respect to the metallic materials. The welding equipment includes a first heating means connected to the pair of electrodes for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit for independently controlling the first and the second heating means.

Welding equipment for metallic materials and method for welding metallic materials

A welding structural partis manufactured by overlapping the surfaces of steel sheets, and forming a weld zone by spot welding. The weld zoneincludes: a weld nugget; and a heat affected zonesurrounding the weld nugget, wherein the hardness in the weld zone increases along an exterior regionof the heat affected zonetoward the heat affected zone, and then decreases along the heat affected zonetoward the central region of the weld nugget. In the boundary region between the weld nuggetand the heat affected zone, the weld nuggetmay have a convex portionA bulging into the heat affected zonealong the overlapped portion. The steel sheetscontain carbon in 0.15 mass % or more.

Welding structural part and welding method of the same

A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipmentsandwiches metallic materialswith a pair of electrodes, and heats different regions of the metallic materialsby energization, with the pair of electrodesmaintained at the same position with respect to the metallic materials. The welding equipment includes a first heating meansconnected to the pair of electrodesfor heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating meansfor heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unitfor independently controlling the first and the second heating means

A high-strength die-quenched partis formed by heating a high-strength steel sheetup to an austenite region, hot stamping and cooling inside a mold, and its microstructure has the martensite wherein carbide particlesare finely dispersed over an entire region including prior-austenite grain boundaries. It is desirable that the prior-austenite grain size in the microstructure of the high-strength steel sheet, which is a base material, be 10 &#x3bc;m or smaller. The high-strength die-quenched part has high-strength and high-ductility thanks to its martensite.

High-strength and high-ductility die-quenched parts and method of manufacturing the same

Growing community of inventors

Kanagawa, Japan

Munehisa Hatta