Patent ID: 6921440

Claim:
An exhaust system manifold comprising niobium-stabilized chromium ferritic steel comprising iron and the following by weight based on total weight: carbon≦0.02% 0.002%≦nitrogen≦0.02% 0.05%≦silicon≦1% 0%<manganese≦1% 0.2%≦niobium≦0.6% 13.5%≦chromium≦16.5% 0.02%≦molybdenum≦1.5% 0%<copper≦1.5% 0%<nickel≦0.2% 0%<phosphorus≦0.020% 0%<sulfur≦0.003% 0.005%<tin≦0.04% zirconium≦0.01%, impurities inherent to smelting, wherein the content of niobium, carbon and nitrogen satisfy the relationship: 9.5≦ Nb/(C+N), and wherein the Nb content satisfies the relationship 0.1≦ΔNb≦0.5, where ΔNb=Nb−7 (C+N).