Stainless steel material and method for manufacturing the same

Abstract

To provide a stainless steel excellent in corrosion resistance and designability of black color even when the stainless steel is exposed to a high temperature environment with salt adhering thereto.SOLUTION: A stainless steel has a raw material and an oxide film formed on the raw material. The raw material includes, on a mass basis, C:0.100% or less, Si:1.00% or less, Mn:0.05-1.00%, Ni:1.00% or less, P:0.100% or less, S:0.100% or less, Cr:16.00-40.00%, N:0.100% or less, Ti:0.08-0.50%, Cu:1.00% or less, and Mo:3.00% or less. The remainder includes a composition including Fe and impurities. The oxide film includes a Cr2O3 inner layer having a thickness of 50 nm or more, and a whole thickness of 300-1000 nm. A Cr concentration in a boundary face between the raw material and the oxide film is 8.0 mass% or less.SELECTED DRAWING: None

Claims

1. A stainless steel material having a base material and an oxide film formed on the base material, The aforementioned material has a composition, by mass, consisting of C: 0.100% or less, Si: 1.00% or less, Mn: 0.05 to 1.00%, Ni: 1.00% or less, P: 0.100% or less, S: 0.100% or less, Cr: 16.00 to 40.00%, N: 0.100% or less, Ti: 0.08 to 0.50%, Cu: 1.00% or less, and Mo: 3.00% or less, with the remainder being Fe and impurities. The aforementioned oxide film has a thickness of 50 nm or more. 2 O 3 It has an inner layer and an overall thickness of 300 to 1000 nm. A stainless steel material in which the Cr concentration at the interface between the material and the oxide film is 8.0% by mass or less.

2. The stainless steel material according to claim 1, wherein the material further comprises at least one selected by mass from Nb: 0.50% or less, Al: 1.00% or less, Zr: 1.00% or less, Co: 1.00% or less, V: 1.00% or less, W: 1.00% or less, REM: 0.100% or less, Ca: 0.100% or less, Sn: 0.100% or less, and B: 0.0100% or less.

3. The aforementioned oxide film is L * a * b * Lightness index L in a color system * If the index is 50.0 or less, the Chromanetics index a * and b * The stainless steel material according to claim 1 or 2, wherein the tolerance is within ±5.

00.

4. The stainless steel material according to claim 1 or 2, wherein the peeling area ratio of the oxide film after a high-temperature corrosion test with salt adhering to it is 5.0% or less.

5. Based on mass, it contains C: 0.100% or less, Si: 1.00% or less, Mn: 0.05 to 1.00%, Ni: 1.00% or less, P: 0.100% or less, S: 0.100% or less, Cr: 16.00 to 40.00%, N: 0.100% or less, Ti: 0.08 to 0.50%, Cu: 1.00% or less and Mo: 3.00% or less, with the balance consisting of Fe and impurities, and has a composition, and for a rolled material with a Vickers hardness of 200 HV or more, O 2 The concentration is 2 to 20% by volume, the water vapor concentration is 20% by volume or less, and the following formula (1): O 2 Concentration + Water vapor concentration ... (1) A method for manufacturing stainless steel material, involving heat treatment at a temperature of 800°C or higher for 1 minute or more in an atmosphere where the value represented by is between 12 and 35.

6. The method for manufacturing stainless steel according to claim 5, wherein the rolled material further comprises at least one selected by mass from Nb: 0.50% or less, Al: 1.00% or less, Zr: 1.00% or less, Co: 1.00% or less, V: 1.00% or less, W: 1.00% or less, REM: 0.100% or less, Ca: 0.100% or less, Sn: 0.100% or less, and B: 0.0100% or less.

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