Nippon Steel Corporation

Aisin Aw Co., Ltd.

Aisin Corporation

Keisuke Matsuzaka

Koji Obayashi

Manabu Kubota

Tatsuya Koyama

Kei Miyanishi

Daisuke Kasai

Kazuaki Okada

Takeshi Ryujin

Takeshi Naito

Masashi Sakakibara

Toshiaki Matsumura

Provided is a method for executing a quenching method in which an object to be treated that is a quenching target is cooled with a quenching coolant that is a coolant for quenching, in which the object to be treated is moved inside the quenching coolant accumulated in a cooling tank, by a moving device for moving the object to be treated, and at least from when the object to be treated comes into contact with the quenching coolant until a surface of the object to be treated undergoes martensitic transformation, a state in which a relative speed of the object to be treated and the quenching coolant is slower than a moving speed of the object to be treated is maintained.

Quenching method

In this steel component, the concentration of C in a surface layer is 0.85 mass % or more to 1.2 mass % or less, which is higher than the concentration of C in a starting material steel, the surface layer has a volume ratio of a retained-austenite structure higher than 0% and lower than 10%, the remainder of the surface layer is a martensitic structure, the area fraction of grain boundary carbides in the surface layer is lower than 2%, a layer inside the surface layer is higher than the surface layer in a volume ratio of a retained-austenite structure, and in the layer inside the surface layer, the remainder is a martensitic structure.

Steel component, gear component, and producing method for steel component

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Okazaki, Japan

Keisuke Matsuzaka