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Eternal
Jiangyin Eternal Heavy Industry Co.,Ltd manufactures custom 316H austenitic stainless steel ring forgings for critical high-temperature service. Produced to ASTM A182 / A336 / A965 specifications and available in AISI 316H (UNS S31609), our ring forgings deliver superior creep rupture strength and corrosion resistance in the 500–870°C range. From Ø200 mm to Ø1,500 mm OD, with both open-die and rolled ring processes.
Parameter | Value |
Material | AISI 316H / UNS S31609 |
Standard | ASTM A182 F316H, ASTM A336 F316H, ASTM A965 F316H |
OD Range | 200 – 3,500 mm (custom up to 15,000 mm available) |
Wall Thickness | 20 – 500 mm |
Tensile Strength | ≥515 MPa |
Yield Strength (0.2%) | ≥205 MPa |
Elongation | ≥40% |
Hardness | ≤95 HRB (≤217 HB) |
Element | Content (wt%) |
C (Carbon) | 0.04 – 0.10 |
Mn (Manganese) | ≤ 2.00 |
Si (Silicon) | ≤ 0.75 |
P (Phosphorus) | ≤ 0.045 |
S (Sulfur) | ≤ 0.030 |
Cr (Chromium) | 16.0 – 18.0 |
Ni (Nickel) | 10.0 – 14.0 |
Mo (Molybdenum) | 2.00 – 3.00 |
The distinguishing feature of 316H versus standard 316 is the controlled carbon range of 0.04–0.10%, which significantly enhances high-temperature creep resistance and rupture strength — essential for components operating continuously at elevated temperatures for 40+ years. The molybdenum addition (2–3%) provides excellent resistance to pitting and crevice corrosion in chloride-bearing environments.
ASTM A182/A182M — Forged or rolled alloy-steel pipe flanges, forged fittings, and valves and parts for high-temperature service. Covers Grade F316H.
ASTM A336/A336M — Alloy steel forgings for pressure and high-temperature parts. Grade F316H specified for pressure vessel and reactor components.
ASTM A965/A965M — Austenitic steel forgings for pressure and high-temperature parts. Includes F316H as a covered grade. Materials are supplied in solution-treated condition (solution annealing followed by quenching in water, oil, or polymer solution).
AISI 316H — Equivalent designation under the American Iron and Steel Institute system.
UNS S31609 — Unified Numbering System designation.
ASME SA-182 / SA-336 / SA-965 — Boiler and Pressure Vessel Code equivalents.
Our 316H ring forgings are produced through a controlled multi-stage process:
Melting — Electric arc furnace (EAF) + AOD/VOD refining, followed by electroslag remelting (ESR) for ultra-clean steel with controlled residual elements.
Ingot Preparation — Ingots are cut, surface-conditioned, and heated to 1150–1240°C for forging.
Open-Die Forging — Upsetting and drawing operations ensure adequate forging ratio (>4:1) for grain refinement and sound internal structure.
Ring Rolling — Radial-axial ring rolling to near-net shape, followed by controlled cooling.
Heat Treatment — Solution annealing per ASTM requirements (details below).
Testing & Inspection — Chemical analysis, mechanical testing, grain size evaluation, ultrasonic testing (UT), and dimensional inspection.
Per ASTM A182 / A336 and industry best practice, 316H ring forgings undergo:
Solution Annealing: 1,040–1,150°C (1,900–2,102°F), followed by rapid quenching in water, oil, or polymer solution.
Grain Size Control: Forging at 1,100°C with ≥30% deformation achieves grain size of approximately ASTM Grade 7. Solution treatment should be controlled within 1,040–1,060°C to homogenize grain structure without causing abnormal grain growth.
The combination of controlled carbon content and optimized solution annealing ensures uniform mechanical properties across the full section of the ring forging, with head-to-tail yield strength variation ≤30 MPa and impact toughness variation ≤50 J.
316H ring forgings have become the material of choice for sodium-cooled fast reactor (SFR) vessel support rings. In 2024, a Ø15.4–15.5 m, 150-tonne weldless integral ring was manufactured from 316H high-purity stainless steel for the CFR-600 demonstration fast reactor. This ring serves as the reactor vessel support structure, bearing approximately 7,000 tonnes of load during 40 years of continuous operation. Near-net-shape forging technology has also produced Ø15.5 m arc segments with uniform grain size and fatigue performance meeting ASME design curves.
316H ring forgings are specified for high-temperature pressure vessels, hydrogenation reactor internals, and heat exchanger components operating above 500°C. Key applications include transfer lines in refinery vacuum distillation units and convection-section tubes in ethylene cracking furnaces. The elevated carbon content of 316H provides the creep strength required for these long-residence, high-temperature services.
316H has been qualified for hydrogen service, with supplementary testing available per NACE TM0284 (HIC) and NACE TM0177 (SSC). The material maintains hydrogen saturation kinetics of approximately 9 ppm with acceptable embrittlement resistance after long-term exposure.
Power generation: Supercritical boiler components, turbine fasteners
Aerospace: Engine fasteners, hot-working molds
Chemical processing: High-temperature reactor rings and flanges
What is the difference between 316H and 316L?
316H (UNS S31609) has a controlled carbon range of 0.04–0.10%, while 316L (UNS S31603) has a maximum carbon of 0.030%. The higher carbon in 316H provides superior creep and rupture strength at temperatures above 500°C, making it the preferred grade for high-temperature structural components. 316L is better suited for welding-intensive applications where sensitization resistance is the primary concern.
What ASTM standard covers 316H ring forgings?
316H ring forgings are typically specified under ASTM A182 F316H (for flange, valve, and fitting forgings), ASTM A336 F316H (for pressure vessel and high-temperature parts), or ASTM A965 F316H (the consolidated austenitic forging specification). We can supply to any of these standards as required.
What is the maximum ring diameter you can produce?
Our standard ring rolling capability covers Ø200 mm to Ø3,500 mm OD. For larger diameters, we can produce segmented arc forgings or employ metal additive forging technology to achieve diameters exceeding Ø5,000 mm. Please contact us with your specific dimensional requirements.
Is 316H ring forging suitable for hydrogen service?
Yes. 316H is widely used in hydrogen production, storage, and transportation equipment. We can perform NACE TM0284 and TM0177 supplementary testing for critical hydrogen/sour service applications to ensure compliance with the latest industry standards.
What heat treatment condition do you supply?
Our 316H ring forgings are supplied in the solution-annealed condition as standard per ASTM requirements, with quenching in water, oil, or polymer solution followed by cooling below 260°C. For applications requiring stabilized properties, additional stress-relief treatment can be performed upon request.
What testing and documentation do you provide?
Standard supply includes: chemical composition certificate, mechanical property test report (tensile, yield, elongation, hardness), grain size evaluation, ultrasonic testing per ASTM A388/A418, and dimensional inspection report. Material test certificates to EN 10204 3.1 or 3.2 are available.
What is the typical lead time?
For standard ring sizes (≤Ø2,000 mm), lead time is approximately 6–8 weeks from order confirmation. For large-diameter forgings (>Ø3,000 mm), typical lead time is 10–14 weeks, depending on material availability and testing requirements.
