Toyota Jidosha Kabushiki Kaisha

Shinya Yamamoto

Masatomo Niihara

Satoshi Yamazaki

Shinobu Okuma

Naoki Sakoda

Tomoaki Ihara

Shoji Kawano

A method for producing a steel plate member (SPM), including: a quenching step for heating the SPM to a temperature higher than an austenite transformation finish temperature Aand subsequently cooling the SPM at a cooling rate (CR) faster than an upper critical CR; and a tempering step for reheating a second region of the SPM to a temperature higher than an austenite transformation start temperature Awithout reheating a first region of the SPM after quenching and subsequently cooling the SPM at a CR slower than a lower critical CR. In the cooling process of the tempering step, the shape of the second region is corrected in a temperature range from a temperature equal to or lower than Ato a temperature equal to or higher than a temperature at which transformation into ferrite and pearlite is finished while maintaining the CR slower than the lower critical CR.

Method for producing steel plate member

An induction heating apparatus of a plate-like member for arranging a plate-like member having a three-dimensional structure so that it is interposed between a pair of plate-like coils and inductively heating the plate-like member, the pair of plate-like coils having a three-dimensional structure that corresponds to the plate-like member and being arranged to be opposed to each other. The plate-like member arranged between the pair of plate-like coils includes a plurality of surfaces in a predetermined cross section perpendicular to a current that flows through the plate-like coil pair, and each of the coils of the plate-like coil pair is divided into a plurality of turns along the direction in which the current flows for at least each of the plurality of surfaces of the plate-like member.

Induction heating apparatus and induction heating method of plate-like member

A heating method capable of changing thermal hysteresis for each part of the center pillar for the vehicle is provided. A heating method includes heating, when the center pillar for the vehicle is annealed, the center pillar by induction heating so that: a strength of a part of the first part other than the flange part becomes higher than that of the flange part of the first part, and the strength of the flange part of the first part becomes higher than that of the second part; and toughness of the second part becomes higher than that of the flange part of the first part, and the toughness of the flange part of the first part becomes higher than that of the part of the first part other than the flange part.

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Toyota, Japan

Shinya Yamamoto