High-strength steel sheet having excellent formality and resistance to softening of the heat affected zone after welding

US6428631B1 · kind B1 · utility

Assignee

• NIPPON STEEL CORPORATION · JP

Inventors

• Toshimasa Tomokiyo · Tokyo, JP
• Hirokazu Taniguchi · Tokai, JP
• Ryo Maruta · Tokai, JP

Key dates

• Filing date: Mar 16, 2000
• Grant date: Aug 6, 2002
• Expiry date: Mar 16, 2020

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22C38/16
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A high-strength steel sheet having excellent fatigue property, excellent formability and resistance to softening of the heat affected zone after welding, comprising: 0.01 to 0.15 mass % of C, 0.005 to 1.0 mass % of Si, 0.1 to 2.2 mass % of Mn, 0.001 to 0.06 mass % of P, 0.001 to 0.01 mass % of S, 0.0005 to 0.01 mass % of N, 0.001 to 0.1 mass % of Al, 0.005 to 0.05 mass % of Nb, 0.05 to 0.5 mass % of Mo, when necessary, 0.001 to 0.02 mass % of Ti, 0.2 to 2.0 mass % of Cu and 0.05 to 2.0 mass % of Ni, and the remainder of Fe, wherein the components satisfy the following expression (A).0.22≧C(%)+(Si/30)(%)+(Mn/20)(%)+(Mo/15)(%)  (A)