Stainless Steel S32615
UNS S32615
S32615 is a high-silicon iron-chromium-nickel austenitic alloy, with about 5 % Si, developed for hot concentrated sulfuric acid and other strongly oxidizing acids where a silicon-rich passive film carries the corrosion duty.
Reference datasheet — S32615 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed condition
S32615 tempers and conditions
S32615 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Finished | Use for heavy bar, forged valve and pump bodies where section size prevents cold finishing. | 285 | 600 | 38 | 175 HB | 1.8 % IACS |
AnnealedDefault solution annealed and quenched (ASTM A240/A312/A276) | Standard supply condition for plate, sheet, tube and bar — maximum corrosion resistance in hot sulfuric acid service. | 300 | 620 | 40 | 180 HB | 1.8 % IACS |
As-welded deposit | Represents welded joints in acid vessels; expect slightly lower ductility and preferential attack risk unless post-weld pickled and passivated. | 330 | 590 | 28 | 195 HB | 1.8 % IACS |
Cold drawn | Choose for straight, close-tolerance bar and fasteners where higher strength is needed; corrosion performance slightly reduced by cold-work stresses unless stress relieved. | 520 | 750 | 22 | 22 HRC | 1.8 % IACS |
What is S32615?
S32615 is a high-silicon iron-chromium-nickel austenitic alloy, with about 5 % Si, developed for hot concentrated sulfuric acid and other strongly oxidizing acids where a silicon-rich passive film carries the corrosion duty. Annealed material gives 300 MPa yield, 620 MPa tensile, 40 % elongation and about 180 HB (88 HRB), with the highest corrosion score (82) in this group; it is supplied annealed, cold drawn, hot finished and as-welded. Silicon makes it abrasive and only moderately machinable (score 30) and formable (60), and it is a niche melt with limited stock and long lead times. S32615 has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,350°C (2,462 °F). S32615 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 190 GPa (27.6 Msi).
What is S32615 used for?
- Sulfuric acid process equipment
- Acid handling components
- Acid coolers and heat exchanger tubing
- Acid distributors and downcomers
- Pump and valve wetted parts for concentrated acid
- Acid storage tank internals and piping
- Absorption tower internals
Advantages
- Good corrosion resistance — 82/100, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- High service temperature — 850°C (1,562 °F), better than 80% of stainless steel grades
Limitations
- Poor heat conductor — 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 93% of stainless steel grades
- Low electrical conductivity — 1.8 % IACS, worse than 87% of stainless steel grades
S32615 properties
Typical room-temperature values for S32615-Annealed; bars are the position among stainless steel grades.
Physical3
S32615 has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,350°C (2,462 °F).
Mechanical16
S32615 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal5
S32615 is rated for continuous service to 850°C (1,562 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 93% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
S32615 conducts electricity at 1.8 % IACS, worse than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of S32615 takes about 72 MJ of energy and emits 5.2 kg of CO₂ — more than 83% of stainless steel grades. Typical recycled content is 40%.
Manufacturability7
S32615's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability good (55/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. S32615 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S32615
Is S32615 easy to machine?
Machines like a tough austenitic but the 5% Si makes it abrasive and gummy — use rigid setups, positive-rake carbide, low speeds/heavy positive feeds and copious coolant to avoid work hardening.
Can S32615 be welded?
GTAW/GMAW/SMAW with matching high-Si S32615 filler; keep interpass temperature low (<150 °C), low heat input and minimal restraint to avoid hot cracking; no post-weld heat treatment normally required.
Can S32615 be formed, bent or molded?
Cold formable but stiffer and less ductile than 304/316 due to Si; hot working in the 1050–1150 °C range with rapid cooling from >1050 °C, and avoid finishing below ~950 °C to prevent edge cracking.
S32615 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | ≤ 0.07 | 0.03 |
| Sikey alloying element for hot H2SO4 resistance | 4.8 – 6 | 5.3 |
| Mn | ≤ 2 | 0.6 |
| P | ≤ 0.05 | |
| S | ≤ 0.03 | |
| Cr | 16.5 – 19.5 | 18 |
| Ni | 19 – 22 | 20 |
| Mo | 0.3 – 1.5 | 0.8 |
| Cu | 1.5 – 2.5 | 1.9 |
| Fe | balance |
What surface finishes work on S32615?
Pickle and passivate (ASTM A380/A967) after welding or heat treatment to restore the silicon-rich passive film; not anodizable, mechanical polishing or electropolishing is used for smooth acid-side surfaces.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
How much does S32615 cost?
S32615 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S32615 — frequently asked
What is S32615 used for?
S32615 is typically used for sulfuric acid process equipment, acid handling components, acid coolers and heat exchanger tubing, acid distributors and downcomers, pump and valve wetted parts for concentrated acid and acid storage tank internals and piping. In short: hot sulfuric acid specialist; highest corrosion score here; abrasive, hard to machine.
What is the yield strength of S32615?
S32615 has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is S32615 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Machines like a tough austenitic but the 5% Si makes it abrasive and gummy — use rigid setups, positive-rake carbide, low speeds/heavy positive feeds and copious coolant to avoid work hardening.
Can S32615 be welded?
Yes — weldability is rated good (55/100). GTAW/GMAW/SMAW with matching high-Si S32615 filler; keep interpass temperature low (<150 °C), low heat input and minimal restraint to avoid hot cracking; no post-weld heat treatment normally required.
What surface finishes work on S32615?
Pickle and passivate (ASTM A380/A967) after welding or heat treatment to restore the silicon-rich passive film; not anodizable, mechanical polishing or electropolishing is used for smooth acid-side surfaces.
Can S32615 be formed, bent or molded?
Cold formable but stiffer and less ductile than 304/316 due to Si; hot working in the 1050–1150 °C range with rapid cooling from >1050 °C, and avoid finishing below ~950 °C to prevent edge cracking.
What is the maximum service temperature of S32615?
S32615 is rated for continuous use to about 850°C (1,562 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S32615 Annealed and S32615-CD?
Annealed is the default condition — standard supply condition for plate, sheet, tube and bar — maximum corrosion resistance in hot sulfuric acid service. CD: choose for straight, close-tolerance bar and fasteners where higher strength is needed; corrosion performance slightly reduced by cold-work stresses unless stress relieved. Yield strength is 300 MPa in Annealed versus 520 MPa in CD.
How much does S32615 cost?
S32615 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A312/A312M — Seamless, Welded Austenitic Stainless Steel Pipes — ASTM International (2022)
- ASTM A276/A479 — Stainless Steel Bars and Shapes — ASTM International (2022)
- High-silicon austenitic stainless steel for concentrated sulfuric acid (UNS S32615) datasheet — Sandvik / Alleima (2022)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.