Bolt

US10669604B2 · kind B2 · utility

Assignees

• NIPPON STEEL CORPORATION · JP
• AOYAMA SEISAKUSHO CO., LTD. · JP

Inventors

• Yutaka Neishi · Tokyo, JP
• Makoto Kosaka · Tokyo, JP
• Naoki Matsui · Kisarazu, JP
• Tetsushi Chida · Tokyo, JP
• Keisuke CHIBA · Toyota, JP
• Hideo Kanisawa · Ebeye, US
• Kazutaka Aoyama · Ebeye, US
• Kazuoki Shibuya · Ebeye, US
• Ryoko Inagaki · Ebeye, US

Key dates

• Filing date: Jun 27, 2016
• Grant date: Jun 2, 2020
• Expiry date: Dec 27, 2036

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

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≤10C+Si+2Mn+Cr+4Mo+5V≤6.1  (1)Mn/Cr≤0.55  (2)[dissolved Cr]/Cr≥0.70  (3)