Stainless Steel S31100
UNS S31100 · AISI/SAE XM-26
S31100 (XM-26) is an early lean duplex stainless with a balanced Cr-Ni-Mo-N chemistry that gives a ferritic-austenitic structure at moderate alloy cost.
Reference datasheet — S31100 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
S31100 tempers and conditions
S31100 is supplied in 6 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot rolled | Thick plate and hot-finished bar for pressure vessels and structural parts where scale/tolerance is machined off. | 490 | 750 | 30 | 22 HRC | 2.2 % IACS |
AnnealedDefault solution annealed and quenched (mill annealed) | Standard supply condition for plate, sheet, bar and pipe; best corrosion resistance and toughness with full duplex phase balance. | 500 | 760 | 30 | 23 HRC | 2.2 % IACS |
As-welded deposit | Reference condition for welded fabrications; expect reduced toughness and pitting resistance unless heat input and filler ferrite balance are controlled. | 500 | 750 | 22 | 24 HRC | 2.2 % IACS |
Cold Rolled + Annealed, 2B finish | Thin sheet and strip for tanks, heat-exchanger and formed components needing a smooth bright surface. | 520 | 780 | 28 | 24 HRC | 2.2 % IACS |
Cold drawn | Cold-drawn bar for shafts, fasteners and machined fittings where tighter tolerance and higher yield are wanted. | 700 | 880 | 20 | 29 HRC | 2.2 % IACS |
Cold Worked, high strength | Choose when maximum strength in small sections matters and ductility/toughness can be traded away; not for welded or SCC-critical service. | 830 | 1,000 | 13 | 33 HRC | 2.2 % IACS |
What is S31100?
S31100 (XM-26) is an early lean duplex stainless with a balanced Cr-Ni-Mo-N chemistry that gives a ferritic-austenitic structure at moderate alloy cost. Engineers use it where 304 and 316 austenitics lack chloride resistance or strength: 500 MPa yield, 760 MPa tensile, 30 % elongation and about 240 HB (99 HRB) in the annealed condition, available as plate, hot- and cold-rolled sheet, cold-drawn bar and welded product. Service is limited to 300 °C, welding needs over-alloyed filler and heat-input control, and stock is scarce — 2205 (S32205) is the modern replacement. S31100 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F). S31100 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 77% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
What is S31100 used for?
- chemical process piping
- pulp and paper equipment
- heat exchangers
Advantages
- High strength — 500 MPa (72.5 ksi), better than 77% of stainless steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
S31100 properties
Typical room-temperature values for S31100-Annealed; bars are the position among stainless steel grades.
Physical3
S31100 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical17
S31100 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 77% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
Thermal5
S31100 is rated for continuous service to 300°C (572 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), better than 53% of stainless steel grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical3
S31100 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of S31100 takes about 53 MJ of energy and emits 4.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
S31100's machinability is poor (33/100, worse than 57% of stainless steel grades); weldability good (62/100); formability fair (48/100).
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. S31100 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S31100
Is S31100 easy to machine?
Machine like 2205: rigid setups, positive-rake carbide, ~30 % of 1212 speeds, heavy feed to cut through the work-hardened skin, flood coolant.
Can S31100 be welded?
GTAW/GMAW/SMAW with 22-9-3 or 25-9-4 over-alloyed filler, no preheat, limited heat input (~0.5–1.5 kJ/mm) and interpass below ~150 °C to keep 40–60 % ferrite; avoid autogenous welds.
Can S31100 be formed, bent or molded?
Cold form with roughly twice the load of 316L and generous springback allowance; hot work 1000–1150 °C followed by solution anneal ~1050 °C and rapid quench.
S31100 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 |
|---|---|---|
| Clow-carbon duplex practice | ≤ 0.08 | 0.03 |
| Crconfirm against governing ASTM/UNS listing | 17.5 – 19.5 | 18.5 |
| Ni | 4.5 – 6.5 | 5.5 |
| Mo | 2.5 – 3 | 2.8 |
| Mn | ≤ 2 | 1.2 |
| Si | ≤ 1.5 | 0.6 |
| Naustenite stabiliser, raises pitting resistance | 0.03 – 0.1 | 0.07 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on S31100?
Pickle and passivate after welding to restore the passive film; electropolishing or mechanical polishing gives a durable bright finish — no anodizing.
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
Equivalent designations
Standards and trade names that resolve to Stainless Steel S31100 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- XM-26
How much does S31100 cost?
S31100 is a premium-cost stainless steel ($$$), cheaper than about 51% 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.
S31100 — frequently asked
What is S31100 used for?
S31100 is typically used for chemical process piping, pulp and paper equipment and heat exchangers. In short: moderate-cost lean duplex; better chloride resistance than 316; largely superseded by 2205.
What is the yield strength of S31100?
S31100 has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 77% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is S31100 easy to machine?
Not especially — machinability is rated poor (33/100, worse than 57% of stainless steel grades). Machine like 2205: rigid setups, positive-rake carbide, ~30 % of 1212 speeds, heavy feed to cut through the work-hardened skin, flood coolant.
Can S31100 be welded?
Yes — weldability is rated good (62/100). GTAW/GMAW/SMAW with 22-9-3 or 25-9-4 over-alloyed filler, no preheat, limited heat input (~0.5–1.5 kJ/mm) and interpass below ~150 °C to keep 40–60 % ferrite; avoid autogenous welds.
What surface finishes work on S31100?
Pickle and passivate after welding to restore the passive film; electropolishing or mechanical polishing gives a durable bright finish — no anodizing.
Can S31100 be formed, bent or molded?
Cold form with roughly twice the load of 316L and generous springback allowance; hot work 1000–1150 °C followed by solution anneal ~1050 °C and rapid quench.
What is the maximum service temperature of S31100?
S31100 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S31100 Annealed and S31100 CW-HS?
Annealed is the default condition — standard supply condition for plate, sheet, bar and pipe; best corrosion resistance and toughness with full duplex phase balance. CW-HS: choose when maximum strength in small sections matters and ductility/toughness can be traded away; not for welded or SCC-critical service. Yield strength is 500 MPa in Annealed versus 830 MPa in CW-HS.
How much does S31100 cost?
S31100 is a premium-cost stainless steel ($$$), cheaper than about 51% 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 A276/A479 — Stainless Steel Bars and Shapes — ASTM International (2022)
- Unified Numbering System for Metals and Alloys (UNS) — SAE/ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Practical Guidelines for the Fabrication of Duplex Stainless Steels — IMOA (2014)
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.