“Galvannealed Steel Sheet And Manufacturing Method Thereof”

Abstract: The present invention relates to a galvannealed steel sheet, comprising: a base iron; and a zinc plating layer containing 7.2 to 10.6 mass% of Fe, 0.2 to 0.4 mass% of Al wherein the zinc plating layer is formed on a surface of the base iron, wherein in a vertical cross-section of the zinc plating layer, an average thickness of a ? phase is 0.2 µm or less, and an average thickness of G phases existing in contact with the base iron is 0.5 µm or less, wherein in the G phase, the one type or more types selected from the group consisting of Ni, Co, Cu, and In are contained 0.5 mass% or more and 10 mass% or less in total in the G phase, and wherein a phase existing in contact with the G phase is a mixed phase of G1 phase and d phase, and a d phase percentage defined by Expression (1) below is 10% or more. d phase percentage = (d phase/G phase contact interface length)/(d phase/G phase contact interface length + G1 phase/G phase contact interface length) × 100 ···(1) Here, the d phase/G phase contact interface length is the length of the interface at which the d phase and the G phase are in contact, and the G1 phase/G phase contact interface length is the length of the interface at which the G1 phase and the G phase are in contact.

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