Patent ID: 9260771
Filing Date: 2016-02-16
CPC Classification: C21D,C22C

Claim Text:
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.