Grade 347H Austenitic Stainless Steel – High-Carbon Niobium-Stabilized Alloy

Description

Grade 347H is the high-carbon variant of Grade 347, optimized for enhanced high-temperature strength and creep resistance. With a carbon range of 0.04-0.10%, it delivers superior mechanical performance at elevated temperatures (up to 850°C) compared to standard 347, while retaining the niobium stabilization that provides exceptional intergranular corrosion resistance. Unlike 347, 347H is designed for high-temperature pressure components, offering improved creep strength and tensile strength under sustained thermal stress. It contains 0.80-1.20% niobium (plus tantalum), ensuring resistance to sensitization and intergranular corrosion, even after welding. Non-magnetic at room temperature and with good weldability, 347H is the preferred choice for critical high-heat, high-pressure applications in power generation, petrochemical, and nuclear industries.

Chemical Composition (wt%)

C: 0.04-0.10, Cr: 17.00-19.00, Ni: 9.00-13.00, Nb+Ta: 0.80-1.20, Mn ≤ 2.00, Si ≤ 1.00, P ≤ 0.045, S ≤ 0.030

Mechanical Properties

Tensile Strength ≥ 515 MPa, Yield Strength ≥ 205 MPa, Elongation ≥ 40%, Hardness ≤ 201 HB

Advantages

Superior high-temperature creep strength vs. 347; niobium-stabilized for intergranular corrosion resistance; excellent weldability; non-magnetic; ideal for high-pressure, high-heat critical components; long-term high-temperature stability.

Applications

High-temperature boiler tubes, petrochemical pressure vessels, nuclear power components, heat exchangers, and industrial heating systems requiring high-heat, high-pressure performance.

Equivalent Grades

AISI 347H, UNS S34709, EN 1.4551, GB 07Cr18Ni11Nb

 

Stainless Steel Suppliers

If you have project requirements for stainless steel, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, wires, etc. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: info@gneestainless.com

 

Testing and Documentation: Factory test certificate, EN 10204 3.1, chemical report, mechanical report, destructive testing report, non-destructive testing report, PMI test report, visual inspection report, third-party inspection report, NABL certified laboratory report.
Packaging: Wooden crate packaging, bubble wrap packaging, steel strapping, or packaging according to customer requirements.