Sihe Steel
Sihe Steel
Grade 409 (UNS S40900) is a stabilized ferritic stainless steel that offers excellent resistance to oxidation and corrosion in environments where carbon steel would rapidly fail. Most famously utilized in combustion and exhaust systems, 409 is alloyed with approximately 11% chromium and specifically stabilized with titanium. This titanium addition inhibits the formation of chromium carbides during high-temperature exposure and welding, preventing intergranular corrosion and maintaining weldability.
Unlike standard carbon steels, 409 retains structural integrity at continuous operating temperatures up to 675°C (1247°F) and intermittent peaks up to 815°C (1500°F). It represents the optimal material choice when cost-effectiveness is a priority and the high-alloy content of grades like 304 or 316 is unnecessary. By choosing 409, engineers secure a robust shield against thermal stress and mild atmospheric corrosion without over-specifying budgets.
Typical specification frameworks conform to ASTM A240/A240M and EN 10088-2 standards. The matrix below defines the elemental balance required to deliver high formability and anti-scale characteristics:
| Element / Property | ASTM A240 Type 409 (UNS S40900) Limit | EN 1.4512 Comparison | Mechanical Conformance |
|---|---|---|---|
| Chromium (Cr) | 10.5% – 11.75% | 10.5% – 11.5% | Yield Strength: ≥ 170 MPa (25 ksi) |
| Titanium (Ti) | 6 x (C + N) min to 0.75% max | [0.15 + 4x(C+N)] to 0.65% | Tensile Strength: ≥ 380 MPa (55 ksi) |
| Carbon (C) | ≤ 0.08% max | ≤ 0.03% max | Elongation in 50mm: ≥ 20% |
| Silicon (Si) | ≤ 1.00% max | ≤ 1.00% max | Hardness (Rockwell B): ≤ 88 Max |
Operates six state-of-the-art production lines featuring high-precision cold rolling mills, automated tension levellers, and integrated slitting systems. This infrastructure guarantees consistent flatness tolerance (±0.05mm) across light gauge sheets and thick plate runs.
We leverage world-class online bright annealing technology. Processing the material in a controlled, oxygen-free hydrogen/nitrogen atmosphere prevents scaling, preserves the surface finish, and eliminates the need for aggressive acid pickling.
Every batch of 409 sheets and coils undergoes a strict validation protocol, including 100% mechanical stretching, flaring, compression, bend testing, and pneumatic airtightness checks. We leave zero room for internal micro-fissures or gauge variation.
Located in the heart of China’s major industrial steel manufacturing region, Liaocheng Sihe Stainless Steel Material LTD benefits from localized raw material networks and low transport overheads. We export over 80% of our production volume to more than 30 countries and regions—including the United States, Germany, Spain, South America, the Middle East, and Southeast Asia.
By establishing deep agreements with major shipping ports (such as Qingdao and Tianjin), we stabilize outbound shipping costs and secure reliable space allotments, shielding our international buyers from the volatile container market fluctuations.
Supports the construction of specialized heat exchangers and coiled setups. We process wall thicknesses up to 3mm with tight radius bending control, preventing outer wall thinning or buckling.
Equipped with automatic laser, mechanical shear, and flame cutters. We can process flat sheets into custom widths or strip sizes with clean edges, ready for direct robotic welding.
From mill finish (2B) to highly reflective decorative polishing (No.4, Hairline, and Mirror). Our surface finishes maintain structural protection while meeting visual requirements.
Critical for automotive exhaust systems and industrial duct integrations. We process flare expansions, neck expansions, and flanged connections without tearing the metal matrix.
Mandatory check for all pressure-retaining components. We verify every weld line and sheet formation under controlled water or air pressure to guarantee long-term system integrity.
Using 409 sheets for housing and 316L/2205 coiled tubing inside, our systems manage extreme thermal exchange, preventing stress corrosion cracking in high-chlorine media.
409 is the foundational alloy for catalytic converter shells, mufflers, and manifold piping. Its high thermal scaling resistance prevents component failure under cyclic exhaust flows.
For processing units handling aggressive organic and inorganic acids, we manufacture components using Incoloy 825 and Inconel 625 to resist pitting, crevice corrosion, and high pressures.
As offshore exploration transitions into deeper waters, standard grades are highly vulnerable to localized corrosion. Liaocheng Sihe is a leading provider of continuous coiled tubing (lengths up to 10,000 meters / 32,800 feet) in duplex alloys like 2205, 2507, and Inconel 625. These subsea umbilical lines withstand extreme mechanical tensile stresses and saline immersion without maintenance, guaranteeing uninterrupted production in deep water operations.
409 sheets and customized stainless steel capillary tubes maintain thermodynamic stability in complex evaporator and condenser coils.
High-purity bright annealed tubing with ultra-smooth inner diameters prevents biological product adhesion and contamination.
Superheated steam delivery pipelines rely on our heat exchanger tubing to resist high-temperature oxidation and maintain consistent pressure ratings.
Global exhaust emission standards (such as Euro VI, China VI, and EPA Tier 4) require engines to operate at higher temperatures for complete combustion. This has driven the shift from simple carbon steel and aluminized steel to 409 and 439 stainless steel for exhaust manifolds and catalyst housings. The stabilization of titanium in 409 is critical here, preventing mechanical breakdown under extreme heat cycles.
Automakers and industrial manufacturers are actively reducing vehicle and equipment weight to improve efficiency. As a result, steel producers must supply thinner, high-strength plates that don't compromise structural integrity. Liaocheng Sihe meets this demand with advanced cold-rolling processes that control sheet thickness down to decimal tolerances, reducing total component weight without losing strength.
The rise of the green hydrogen economy requires piping and containment systems that resist hydrogen embrittlement. Standard ferritic and austenitic steels are being upgraded with special alloying additions. Liaocheng Sihe is adapting to these trends by expanding our production of stabilized and duplex grades, ensuring compatibility with hydrogen fuel cell infrastructure and CCS applications.
Modern steel processing lines utilize AI-powered thickness gauges and laser surface inspectors to identify surface defects, gauge variations, and impurities in real time. We integrate optical inspection technologies directly into our processing lines, ensuring that every 409 sheet or coil shipped to our global customers is physically sound and matches technical specifications.
Liaocheng Sihe Stainless Steel Material LTD operates under a strict Quality Management System (QMS) certified to international benchmarks. Every product shipment includes complete documentation, including Mill Test Certificates (MTC) matching EN 10204 3.1, chemical composition breakdowns, and mechanical testing records.
Our processing lines conform to standards such as ASTM A240/A269 and JIS G4305. This rigorous compliance allows our materials to be integrated directly into demanding projects, including petrochemical pipelines, automotive exhaust assemblies, and deep-sea umbilical cables.
