more stable to heat ferritic stainless steel with excellent properties at low temperatures, toughness, weldability and thermal resistance.

摘要

A heat-resistant ferritic stainless steel improved in low-temperature toughness, prevented from undergoing high-temperature weld crack, and useful as a material of a passage of automobile exhaust gas, particularly a passage exposed to high temperature between an engine and a converter, which comprises up to 0.03 % of carbon, 0.1 to 0.8 % of silicon, 0.6 to 2.0 % of manganese, up to 0,006 % of sulfur, up to 4 % of nickel, 17.0 to 25.0 % of chronium, 0.2 to 0.8 % of niobium, 1.0 to 4.5 % of molybdenum, 0.1 to 2.5 % of copper, up to 0.03 % of nitrogen, and optionally a necessary amount of at least one of aluminum, titanium, vanadium, zirconium, tungsten, boron and REM, wherein the manganese to sulfur ratio is 200 or above, [Nb]=Nb % - 8(C % + N %) /= 0.2, and Ni % + Cu % /= 4, the balance being iron and inevitable impurities in the production process.