Ni-added steel plate and method of manufacturing the same

摘要

A Ni-added steel plate includes, by mass %, C: 0.04% to 0.10%, Si: 0.02% to 0.12%, Mn: 0.3% to 1.0%, Ni: more than 7.5% to 10.0%, Al: 0.01% to 0.08%, T.O: 0.0001% to 0.0030%, P: limited to 0.0100% or less, S: limited to 0.0035% or less, N: limited to 0.0070% or less, and the balance consisting of Fe and unavoidable impurities, in which a Ni segregation ratio at an area of ¼ of a plate thickness away from a plate surface in a thickness direction is 1.3 or less, a fraction of austenite after a deep cooling is 0.5% or more, an austenite unevenness index after the deep cooling is 3.0 or less, and an average equivalent circle diameter of the austenite after the deep cooling is 1 μm or less.

主权项

1. A Ni-added steel plate comprising, by mass %:
C: 0.04% to 0.10%; Si: 0.02% to 0.12%; Mn: 0.3% to 1.0%; Ni: more than 7.5% to 10.0% or less; Al: 0.01% to 0.08%; T.O: 0.0001% to 0.0030%; P: limited to 0.0100% or less; S: limited to 0.0035% or less; N: limited to 0.0070% or less; and the balance of Fe and unavoidable impurities, wherein a Ni segregation ratio at an area of ¼ of a plate thickness away from a plate surface in a thickness direction is 1.3 or less, a fraction of austenite, an austenite unevenness index, and an average equivalent circle diameter of the austenite measured in a deep cooled sample of the Ni-added steel plate is 0.5% or more, 3.0 or less, and 1 μm or less, respectively.