Patent ID: 11091824

Abstract:
A ferritic stainless steel and a heat exchanger using the ferritic stainless steel are provided. The ferritic stainless steel includes, in mass %, C: 0.030% or less, N: 0.020% or less, Si: 0.5% or less, Mn: 1.0% or less, P: 0.05% or less, S: 0.01% or less, Cr: 16% to 25%, Nb: 0.05% to 1.0%, Al: 0.003% to 0.20%, and a balance comprising Fe and unavoidable impurities. The Al oxide is present on the surface of the material, the surface coverage ratio by the Al oxide is 5% to 70%, the surface roughness in Ra measured by red laser is 0.010-0.15 μm, and the thickness from the surface to the point, which includes the value of a half peak of the Al content on the surface, satisfies 300 nm or less, the value of a half peak of the Al content in an elemental profile expressed by a cation ratio.