Description
Why 309S Outperforms in Red-Hot Conditions
Oxidation Shield
Forms a stable Cr₂O₃ layer at 900°C+ (50% slower scaling vs. 304H).
Thermal Fatigue Fighter
Survives 5.000+ rapid heat-cool cycles (ASTM E606 verified).
Carburization Barrier
Blocks carbon ingress in ethylene cracker tubes (API 934 compliant).
Weld-Safe Design
Low carbon (0.03% max) prevents HAZ cracking in high-heat joints.
Critical High-Temp Metrics
| Property |
309S Plate |
Competitor (310S) |
| Max Continuous Temp |
1.100°C (with <0.1% scaling/year) |
1.150°C (higher cost per °C gain) |
| Thermal Conductivity |
14.9 W/m·K @ 500°C |
13.4 W/m·K (slower heat dispersion) |
| Cyclic Endurance |
5% weight loss after 1.000h @ 950°C |
7% weight loss (same conditions) |
| Cost Efficiency |
$6.2/kg (12mm annealed) |
$9.8/kg (25% premium for 50°C gain) |
Industry-Specific Dominance
1. Petrochemical Processing
Cracking furnace tubes | Sulfur recovery unit liners
2. Heat Treatment
Annealing trays | Carburizing furnace muffles
3. Energy Generation
Boiler baffle plates | Waste incinerator internals
4. Automotive Exhaust
Turbocharger housings | Diesel particulate filter shells
Global Success Stories
Qatar Gas Refinery: “309S plates doubled pyrolysis tube lifespan vs. 304H.”
Bavarian Heat Treat Co.: “Cut furnace muffle replacement costs by 40% annually.”
Detroit Auto Supplier: “Eliminated exhaust warping in -40°C to 800°C cycles.”
Fabrication Expertise
Q: Best welding practice for 309S-to-carbon steel joints?
A: Use ER309L filler with 60–80°C preheat; avoid post-weld stress relief.
Q: Surface finish for oxidation resistance?
A: Mill finish (2B) outperforms polished surfaces in scaling tests.
Q: Minimum thickness for furnace applications?
A: 6mm for structural parts | 3mm for shielding with ceramic coatings.
