Ferritic stainless steel sheet with excellent thermal fatigue properties, and automotive exhaust-gas path member

Abstract

Disclosed is a ferritic stainless steel sheet with excellent thermal fatigue properties, including, by mass %, 0.03% or less of C, 1.0% or less of Si, 1.5% or less of Mn, 0.6% or less of Ni, 10˜20% of Cr, 0.05˜0.30% of Ti, 0.51˜0.65% of Nb, 0˜less than 0.10% of Mo, 0.8˜2.0% of Cu, 0˜0.10% of Al, 0.0005˜0.02% of B, 0˜0.20% of V, and 0.03% or less of N, with the balance being Fe and inevitable impurities, having a composition satisfying the following equations (1) and (2) and having a structure in which ε-Cu phase grains each having a long diameter of 0.5 μm or more are present in a density of 10 or less per 25 μm2: Nb−8(C+N)≧0 . . . (1), 10 Si+20 Mo+30 Cu+20(Ti+V)+160 Nb−(Mn+Ni)≧100 . . . (2). The ferritic stainless steel sheet, having a relatively inexpensive component composition, has excellent thermal fatigue properties, and is suitable for use in an automotive exhaust-gas path member, including an exhaust manifold, a catalyst converter, a front pipe, or a center pipe.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a stainless steel sheet with excellent thermal fatigue properties, and to an automotive exhaust-gas path member using the same, and in particular, to a member that constitutes the upstream part of the exhaust-gas path and is heated to temperatures of 700° C. or higher upon the use of automobiles.

[0003] 2. Description of the Related Art

[0004] Among automotive exhaust-gas path members, an upstream member, which is heated to 700° C. or higher during use thereof, is required to have, first of all, heat resistance in a range of high temperatures exceeding 700° C. In this regard, with the main goal of increasing high-temperature strength in the high-temperature range of 700˜1000° C., characteristic materials therefor have been developed. Further, the automotive exhaust-gas path member undergoes repeated heat cycles, including heating to the high-temperature range and cooling to room temperature,...