熱延鋼板およびその製造方法

Title:

熱延鋼板およびその製造方法

Document Type and Number:

Japanese Patent JP5605526

Kind Code:

B2

Abstract:

Provides is a high strength hot rolled steel sheet with low yield ratio which is excellent in low-temperature toughness and can be preferably used as a raw material of a steel pipe. The steel sheet has a chemical composition containing C: 0.03% or more and 0.10% or less, Si: 0.01% or more and 0.50% or less, Mn: 1.4% or more and 2.2% or less, P: 0.025% or less, S: 0.005% or less, Al: 0.005% or more and 0.10% or less, Nb: 0.02% or more and 0.10% or less, Ti: 0.001% or more and 0.030% or less, Mo: 0.01% or more and 0.50% or less, Cr: 0.01% or more and 0.50% or less, and Ni: 0.01% or more and 0.50% or less, in which the condition that Moeq is 1.4% or more and 2.2% or less is preferably satisfied, and a microstructure in an inner layer including a bainitic ferrite phase as a main phase and, in terms of area fraction, 1.4% or more and 15% or less of a massive martensitic phase having an aspect ratio of less than 5.0 as a second phase, in which the lath thickness of the bainitic ferrite phase is 0.2 µm or more and 1.6 µm or less. It is preferable that the size of the massive martensitic phase be 5.0 µm or less at most and 0.5 µm or more and 3.0 µm or less on average.

Inventors:

Above Power
Goto 聡太

Application Number:

JP2014510587A

Publication Date:

October 15, 2014

Filing Date:

September 11, 2013

Export Citation:

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