Stainless Steel XM-15
UNS S38100
XM-15 (UNS S38100) is a silicon-enhanced 18Cr-18Ni austenitic stainless steel developed to avoid the sensitization and intergranular corrosion seen with 304 and 316 in nitric acid service.
Reference datasheet — XM-15 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
XM-15 tempers and conditions
XM-15 is supplied in 7 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault solution annealed (~1040–1120 °C, water quenched) | Standard stock condition for plate, sheet, bar and tube; maximum corrosion resistance and ductility. | 260 | 590 | 52 | 160 HB | — |
Hot rolled | Lowest-cost heavy sections for later machining; must be solution annealed before corrosive service. | 290 | 600 | 45 | 180 HB | 2 % IACS |
Cold drawn | Pick for straight, close-tolerance bar with higher yield strength and better machining chip control than annealed. | 450 | 690 | 32 | 16 HRC | 2 % IACS |
Quarter hard | Light cold work for springy sheet parts that still need appreciable bend ductility. | 520 | 760 | 25 | 22 HRC | 2 % IACS |
Half hard | Use where higher strength flat stock is needed and forming is limited to gentle bends. | 690 | 900 | 15 | 28 HRC | 2 % IACS |
Three-quarter hard | Near-maximum strength strip for flat springs and clips with minimal forming. | 830 | 1,010 | 10 | 32 HRC | 2 % IACS |
Full hard | Maximum as-rolled strength for spring wire and shims; essentially no forming capability. | 930 | 1,100 | 7 | 35 HRC | 2 % IACS |
What is XM-15?
XM-15 (UNS S38100) is a silicon-enhanced 18Cr-18Ni austenitic stainless steel developed to avoid the sensitization and intergranular corrosion seen with 304 and 316 in nitric acid service. Annealed stock gives 260 MPa yield, 590 MPa tensile and 52% elongation at 160 HB (82 HRB), with service to 950 °C, a weldability rating of 80/100 and formability of 78/100; it is available annealed, hot rolled, cold drawn and in quarter-, half-, three-quarter- and full-hard tempers. The 2% silicon makes it more abrasive to machine than 304, and with a corrosion rating of 66/100 it is not a substitute for molybdenum grades in chloride service. 304L or 321 covers general fabrication work. XM-15 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,370°C (2,498 °F). XM-15 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 52% and the elastic modulus is 196 GPa (28.4 Msi).
What is XM-15 used for?
- Nitric acid plant equipment
- Chemical process vessels
- Acid piping and fittings
- Heat exchanger tubing
- Welded tanks for oxidizing acids
- Furnace and heat-resisting fixtures
- Process ductwork
Advantages
- Ductile — tolerates forming and impact — 52%, better than 95% of stainless steel grades
- Forms and bends easily — 78/100, better than 90% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- High service temperature — 950°C (1,742 °F), better than 86% of stainless steel grades
- Readily welded — 80/100, better than 80% of stainless steel grades
Limitations
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 83% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
XM-15 properties
Typical room-temperature values for XM-15-Annealed; bars are the position among stainless steel grades.
Physical3
XM-15 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical14
XM-15 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 52% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
XM-15 is rated for continuous service to 950°C (1,742 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 72% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
XM-15 conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 59% of stainless steel grades.
Sustainability4
Producing a kilogram of XM-15 takes about 58 MJ of energy and emits 5.6 kg of CO₂ — more than 66% of stainless steel grades. Typical recycled content is 55%.
Manufacturability8
XM-15's machinability is fair (38/100, better than 63% of stainless steel grades); weldability very good (80/100); formability very good (78/100).
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. XM-15 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with XM-15
Is XM-15 easy to machine?
Gummy and work-hardening like 304 but more abrasive due to 2% Si — use rigid setups, positive-rake carbide, heavy constant feed, no dwelling, and flood coolant.
Can XM-15 be welded?
Weldable by GTAW/GMAW/SMAW with 308/309-type or matching high-Si filler; low heat input, no preheat, and normally no post-weld anneal since the grade resists sensitization.
Can XM-15 be formed, bent or molded?
Good cold formability with a lower work-hardening rate than 301/304 thanks to 18% Ni; allow generous bend radii in hard tempers and interstage anneal at 1040–1120 °C followed by rapid cooling.
XM-15 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 | ≤ 0.08 | 0.04 |
| Mn | ≤ 2 | 1.2 |
| Sikey addition for oxidizing-acid and oxidation resistance | 1.5 – 2.5 | 2 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 17 – 19 | 18 |
| Ni | 17.5 – 18.5 | 18 |
| Fe | balance |
What surface finishes work on XM-15?
Pickle and passivate (ASTM A967 nitric or citric) after fabrication; the Si-rich scale from hot work needs aggressive pickling or abrasive removal, and the alloy polishes and electropolishes well.
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 XM-15 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S38100
How much does XM-15 cost?
XM-15 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.
XM-15 — frequently asked
What is XM-15 used for?
XM-15 is typically used for nitric acid plant equipment, chemical process vessels, acid piping and fittings, heat exchanger tubing, welded tanks for oxidizing acids and furnace and heat-resisting fixtures. In short: sensitization-resistant nitric acid grade; silicon-bearing 18Cr-18Ni austenitic; lower work-hardening than 304.
What is the yield strength of XM-15?
XM-15 has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is XM-15 easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Gummy and work-hardening like 304 but more abrasive due to 2% Si — use rigid setups, positive-rake carbide, heavy constant feed, no dwelling, and flood coolant.
Can XM-15 be welded?
Yes — weldability is rated very good (80/100). Weldable by GTAW/GMAW/SMAW with 308/309-type or matching high-Si filler; low heat input, no preheat, and normally no post-weld anneal since the grade resists sensitization.
What surface finishes work on XM-15?
Pickle and passivate (ASTM A967 nitric or citric) after fabrication; the Si-rich scale from hot work needs aggressive pickling or abrasive removal, and the alloy polishes and electropolishes well.
Can XM-15 be formed, bent or molded?
Good cold formability with a lower work-hardening rate than 301/304 thanks to 18% Ni; allow generous bend radii in hard tempers and interstage anneal at 1040–1120 °C followed by rapid cooling.
What is the maximum service temperature of XM-15?
XM-15 is rated for continuous use to about 950°C (1,742 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between XM-15 Annealed and XM-15-FH?
Annealed is the default condition — standard stock condition for plate, sheet, bar and tube; maximum corrosion resistance and ductility. FH: maximum as-rolled strength for spring wire and shims; essentially no forming capability. Yield strength is 260 MPa in Annealed versus 930 MPa in FH.
How much does XM-15 cost?
XM-15 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 A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- SAE/ASTM DS-56 Metals & Alloys in the Unified Numbering System (UNS S38100) — SAE International / ASTM (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
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.