347H Stainless Steel: High-Carbon Stabilized Alloy

 

What defines 347H's chemical makeup?​

It contains 17-19% chromium, 9-13% nickel, 0.04-0.10% carbon, and 0.75-1.5% niobium (plus tantalum). The higher carbon content boosts high-temperature strength, while niobium stabilizes against intergranular corrosion.​

 

How does 347H perform under high temperatures?​

347H retains strength well up to 1500°F (816°C), outperforming standard 347 in high-heat, high-pressure applications. Its high carbon content enhances creep resistance, critical for parts under sustained stress at elevated temps.​

 

What are its corrosion resistance properties?​

It offers good resistance to intergranular corrosion, even after welding, thanks to niobium. In aqueous environments, its performance is similar to 304, resisting general corrosion but not as well as 316 in chloride-rich settings.​

 

How does 347H handle fabrication and welding?​

It's weldable with proper techniques, though the high carbon requires controlled heat input to prevent carbide precipitation. It has moderate formability, suitable for bending and rolling, but work-hardens with cold working.​

 

What are 347H's typical applications?​

Commonly used in pressure vessels, boiler tubes, and heat exchangers in power plants. It's also found in industrial furnace components that operate under both high heat and pressure.