Aoyama Seisakusho Co., Ltd.

Nippon Steel Corporation

Kazuoki Shibuya

Yutaka Neishi

Naoki Matsui

Hideo Kanisawa

Yukinori Fujimoto

Kazuhiro Koga

Makoto Kosaka

Tetsushi Chida

Keisuke Chiba

Naoki Inaba

Satoshi Iida

Kazutaka Aoyama

Ryoko Inagaki

Yuki Nishimura

A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3).4.9&#x2264;10C+Si+2Mn+Cr+4Mo+5V&#x2264;6.1&#x2003;&#x2003;(1)Mn/Cr&#x2264;0.55&#x2003;&#x2003;(2)[dissolved Cr]/Cr&#x2265;0.70&#x2003;&#x2003;(3)

Bolt

The bolt of the present invention can reliably peel coating even when fastened with a low torque, and can secure sufficient conductivity. A coating peeling part for peeling coating is formed at a tip end of an axis part in which a regular screw part is formed. The coating peeling part includes crushing parts having a trapezoidal top part and having a flank which is projected at a different angle with respect to the flank of the regular screw part; and a protruding part which is arranged adjacent to the crushing parts and whose top part projects beyond the outer diameter of the regular screw part.

Growing community of inventors

Aichi, Japan

Kazuoki Shibuya