347H Stainless Steel: High-Carbon for Extreme Heat Strength

 

What defines 347H's chemical composition?​

It contains 17-19% chromium, 9-13% nickel, 0.75-1.5% niobium (plus tantalum), and carbon 0.04-0.10%. The higher carbon and niobium enhance creep strength, critical for long-term service at extreme temperatures.​

 

How does 347H perform in high-temperature settings?​

347H excels in continuous use up to 816°C, with superior creep resistance compared to 347. It resists oxidation and scaling in high-heat, high-pressure environments, ideal for boiler tubes and turbine components.​

 

What are its corrosion resistance properties?​

It offers excellent resistance to intergranular corrosion after welding, thanks to niobium stabilizing carbon. It performs well in high-temperature steam and mild chemicals, though less resistant to chlorides than 316H.​

 

How does 347H compare to 347 in applications?​

347H is used in high-pressure, high-heat systems like power plant boilers, where 347's lower carbon limits strength. 347 suits lower-pressure high-temperature equipment like furnace parts.​

 

Where is 347H commonly used?​

Found in boiler superheater tubes, nuclear reactor piping, and gas turbine components. It's also used in petrochemical processing equipment operating at elevated temperatures and pressures.