High-strength cold-rolled steel sheet and method for manufacturing the same

US9631250B2 · kind B2 · utility

Assignee

• JFE Steel Corporation · JP

Inventors

• Hidetaka Kawabe · Tokyo, JP
• Takeshi Yokota · Tokyo, JP
• Reiko Sugihara · Chiba, JP
• Shigeyuki Aizawa · Tokyo, JP
• Kazuki Nakazato · Tokyo, JP

Key dates

• Filing date: Feb 28, 2013
• Grant date: Apr 25, 2017
• Expiry date: Jul 13, 2033

Classification

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

Abstract

A steel sheet has a microstructure including ferrite phase: 40% to 60%, bainite phase: 10% to 30%, tempered martensite phase: 20% to 40%, and retained austenite phase: 5% to 20% by volume fraction, and satisfying a condition that a ratio of tempered martensite phase having major axis length ≦5 μm to a total volume fraction of the tempered martensite phase is 80% to 100%.