309/309S Stainless Steel Coil is a high-alloy austenitic stainless steel specifically designed for excellent oxidation resistance and elevated temperature strength in continuous service up to 1150°C. With a balanced composition of 22-24% chromium and 12-15% nickel, 309 grade bridges the performance gap between standard 304/316 grades and premium 310S, offering superior high-temperature capability while maintaining good fabricability and weldability. The "S" variant (309S) features lower carbon content (≤0.08%) for improved resistance to sensitization in welded structures, making it suitable for applications involving both high temperatures and fabrication.

Supplied in continuous coil form, 309/309S provides manufacturers with a cost-effective solution for applications requiring better high-temperature performance than 304 but where the premium cost of 310S may not be justified. This grade excels in intermittent high-temperature applications, offering excellent resistance to oxidation, carburization, and sulfidation while maintaining structural integrity during thermal cycling. Its balanced alloy composition makes it particularly suitable for heat treatment fixtures, furnace components, and thermal processing equipment that operate in the 800-1100°C range.