FERRITIC STAINLESS STEEL SHEET

To provide a high purity ferritic stainless steel sheet excellent in rusting resistance.SOLUTION: A ferritic stainless steel sheet comprises, in mass%, 0.02% or less of C, 1.00% or less of Si, 1.00% or less of Mn, 0.040% or less of P, 0.006% or less of S, 10-30% of Cr, 0.01-0.20% of Al, 0.35% or less of Ti, 0.70% or less of Nb, 0.0005-0.010% of O, 0.050% or less of N, 0.0030% or less of Ca, 0.008×[%Al]-0.003% of Mg, and the balance of Fe and impurities, where the number density of a Ca and S-containing oxide-based inclusion having a circle-equivalent diameter of 4 μm or more is less than 1.0/cm2 on the surface of the steel sheet, and the number ratio of an inclusion having a mass ratio of MgO/Al2O3 of 0.40 or more in the Ca and S-containing oxide-based inclusion having a circle-equivalent diameter of 4 μm or more is 50% or more.SELECTED DRAWING: Figure 1 【課題】耐発銹性に優れる高純度フェライト系ステンレス鋼板を提供する。【解決手段】質量％で、Ｃ：０．０２％以下、Ｓｉ：１．００％以下、Ｍｎ：１．００％以下、Ｐ：０．０４０％以下、Ｓ：０．００６％以下、Ｃｒ：１０～３０％、Ａｌ：０．０１～０．２０％、Ｔｉ：０．３５％以下、Ｎｂ：０．７０％以下、Ｏ：０．０００５～０．０１０％、Ｎ：０．０５０％以下、Ｃａ：０．００３０％以下、Ｍｇ：０．００８×［％Ａｌ］～０．００３％を含有し、残部Ｆｅおよび不純物からなり、鋼板表面において、円相当径４μｍ以上のＣａとＳ含有酸化物系介在物の個数密度が１．０個／ｃｍ２未満であり、かつ、前記円相当径４μｍ以上のＣａとＳ含有酸化物系介在物のうち、ＭｇＯ／Ａｌ２Ｏ３の質量比率が０．４０以上である介在物の個数割合が５０％以上であることを特徴とするフェライト系ステンレス鋼板。【選択図】図１