Name: UNS S32615 Specifications | ASTM A182 High Silicon Stainless Steel
Brand: Solitaire Overseas

Premium grade forging alloy for pressure-retaining components in extreme high-temperature service. Solitaire Overseas supplies certified UNS S32615 material globally — from flanges and fittings to valve bodies and fasteners.

550

MPA MIN UTS

220

MPA MIN YIELD

6.0%

MAX SILICON

990°C

MAX MECH TEMP

7.6

G/CM³ DENSITY

192

HBW MAX

Overview & Key Features

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4.8–6.0% Silicon Content

Elevated silicon provides superior oxidation and corrosion resistance in high-temperature environments, forming a stable protective oxide layer.

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Austenitic Structure

Fully austenitic in the solution-annealed condition, delivering excellent toughness, non-magnetic behaviour, and consistent microstructure.

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Corrosion Resistance

Outstanding resistance to nitric acid, sulphuric acid, and oxidising media — enabled by high Cr (up to 19.5%) and Ni (up to 22%) content.

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Up to 990°C Service Rating

Rated for mechanical service up to 990°C and corrosion resistance up to 410°C, making it ideal for demanding thermal environments.

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Pressure-Retaining Design

Specifically engineered per ASTM A182 for flanges, fittings, valve bodies, and fasteners in pressure-critical applications.

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Good Formability

25% minimum elongation and high reduction in area allow complex forging geometries with reliable dimensional integrity.

Chemical Composition

Iron Balance (~46.4–57.9%)

Nickel 19.00 – 22.00%

Chromium 16.50 – 19.50%

Silicon 4.80 – 6.00%

Element	Symbol	Min %	Max %	Limit Type
Carbon	C	—	0.070	Max
Silicon	Si	4.800	6.000	Range
Manganese	Mn	—	2.000	Max
Phosphorus	P	—	0.045	Max
Sulphur	S	—	0.030	Max
Chromium	Cr	16.500	19.500	Range
Nickel	Ni	19.000	22.000	Range
Copper	Cu	1.500	2.500	Range
Molybdenum †	Mo	0.300	1.500	Range
Iron	Fe	—	—	Balance

Mechanical Properties

550 MPa

Tensile Strength (min)

220 MPa

Yield Strength (min)

25 %

Elongation (min)

192 HBW

Brinell Hardness (max)

Property	SI Value	Imperial Value	Condition
Tensile Strength (UTS)	550 MPa min	80 ksi min	Annealed
Yield Strength (0.2% Proof)	220 MPa min	32 ksi min	Annealed
Elongation (2 in. / 50 mm)	25% min	25% min	Annealed
Brinell Hardness	192 HBW max	—	Annealed
Tensile Strength (Typical)	620 MPa	90 ksi	Annealed
Yield Strength (Typical)	250 MPa	36 ksi	Annealed
Elastic Modulus (Young's)	190 GPa	28 × 10⁶ psi	Annealed
Shear Modulus	75 GPa	11 × 10⁶ psi	Annealed
Poisson's Ratio	0.28	0.28	—
Fatigue Strength	180 MPa	26 ksi	Annealed
Shear Strength	400 MPa	58 ksi	Annealed
Brinell Hardness (Typical)	170 HBW	—	Annealed
Elongation at Break (Typical)	28%	—	Annealed
Reduction in Area (Typical)	46%	—	Annealed

Physical & Thermal Properties

Physical Properties

Density 7.6 g/cm³ (480 lb/ft³)

PREN (Pitting Resistance) 21

Embodied Energy 63 MJ/kg

Embodied Carbon 4.4 kg CO₂/kg

Thermal Properties

Melting Point (Solidus) 1310°C (2380°F)

Melting Point (Liquidus) 1350°C (2460°F)

Specific Heat Capacity 500 J/kg·K

Thermal Expansion 15 µm/m·K

Latent Heat of Fusion 370 J/g

Max. Temp: Mechanical 990°C (1810°F)

Max. Temp: Corrosion 410°C (780°F)

Heat Treatment

Process

Solution Annealing

Heat uniformly to solution annealing temperature, hold for sufficient time, then quench in water or rapidly cool by other means to produce a fully austenitic microstructure.

Temperature

≥ 1065°C (1950°F)

Minimum annealing temperature with rapid quenching thereafter. Ensures complete dissolution of carbides and a stable, single-phase austenitic structure.

Notes

Cold Working & PWHT

Cold working is not applicable as a hardening mechanism; the grade relies on solid-solution strengthening. Post-weld heat treatment is not typically required, though full solution annealing may be specified where intergranular corrosion risk exists.

Related Specifications & Standards

ASTM A182 / A182M

Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves for High-Temperature Service — primary specification for UNS S32615.

ASTM A479

Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels.

ASTM A240

Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and General Applications.

ASTM A312

Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes — sister product form specification for S32615.

ASTM A959

Standard Guide for Specifying Harmonised Standard Grade Compositions for Wrought Stainless Steels.

ASME SA-182

ASME equivalent of ASTM A182 governing use in pressure vessel and boiler components under the ASME Boiler and Pressure Vessel Code.

Typical Applications

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Flanges

Weld neck, slip-on, blind, threaded

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Pipe Fittings

Elbows, tees, reducers, couplings

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Valve Bodies

Gate, globe, check, ball valves

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Fasteners

Bolts, studs, nuts, threaded rods

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Plates & Bars

Forged and machined flat products

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Rings & Discs

Pressure-retaining ring forgings

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Chemical Processing

Nitric acid, sulphuric acid environments

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Power Generation

Superheated steam lines, turbine components

UNS S32615 Products

Solitaire Overseas stocks and supplies UNS S32615 across all major product forms. Explore the range below or contact us for custom requirements and mill test reports.

UNS S32615 Pipe UNS S32615 Tube UNS S32615 Plate UNS S32615 Sheet UNS S32615 Fittings UNS S32615 Flanges UNS S32615 Round Bar