254 SMO (S31254) vs 904L vs XM-19: Which High-Alloy Stainless Steel Is Right for Your Application?
At FULLERKREG, we regularly help engineers and procurement teams select the correct high-alloy stainless steel for demanding corrosion environments. Three grades that frequently come up in the same conversation are 254 SMO (S31254), 904L (N08904), and XM-19 (S20910) — all austenitic stainless steels with enhanced corrosion resistance, but with meaningfully different compositions, mechanical properties, and cost profiles.
This technical guide breaks down the chemical composition and mechanical properties of each grade side by side, so you can make an informed material selection decision.
Overview
- 254 SMO (S31254) — A 6% molybdenum super-austenitic stainless steel with exceptional resistance to pitting and crevice corrosion in chloride-rich environments. Governed by ASTM A276 / S31254.
- 904L (N08904) — A high-alloy austenitic stainless with added copper for improved resistance to sulfuric acid and reducing acids. Governed by ASTM A276 / N08904.
- XM-19 (S20910) — A nitrogen-strengthened austenitic stainless offering significantly higher strength than standard 316L while maintaining good corrosion resistance. Governed by ASTM A276 / S20910.
Chemical Composition Comparison
All values are weight percent (%). Min = minimum required; Max = maximum allowed per ASTM A276.
254 SMO — S31254 (ASTM A276)
| C | Mn | P | S | Si | Cr | Ni | Mo | N | Cu | |
|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | — | — | — | — | 19.5 | 17.5 | 6.0 | 0.18 | 0.50 |
| Max | 0.02 | 1.0 | 0.03 | 0.010 | 0.80 | 20.5 | 18.5 | 6.5 | 0.25 | 1.0 |
904L — N08904 (ASTM A276)
| C | Mn | P | S | Si | Cr | Ni | Mo | N | Cu | |
|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | — | — | — | — | 19.0 | 23.0 | 4.0 | — | 1.0 |
| Max | 0.02 | 2.0 | 0.045 | 0.035 | 1.0 | 23.0 | 28.0 | 5.0 | 0.10 | 2.0 |
XM-19 — S20910 (ASTM A276)
| C | Mn | P | S | Si | Cr | Ni | Mo | N | Nb | V | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | 4.0 | — | — | — | 20.5 | 11.5 | 1.5 | 0.2 | 0.1 | 0.1 |
| Max | 0.06 | 6.0 | 0.045 | 0.035 | 1.0 | 23.5 | 13.5 | 3.0 | 0.4 | 0.3 | 0.2 |
Mechanical Properties Comparison
254 SMO (S31254) — Mechanical Properties
| Tensile Strength Rm (N/mm²) | Yield Strength Rp0.2 (N/mm²) | Elongation A (%) | Hardness HB |
|---|---|---|---|
| ≥650 | ≥300 | ≥35 | ≤50 |
904L (N08904) — Mechanical Properties
| Tensile Strength Rm (N/mm²) | Yield Strength Rp0.2 (N/mm²) | Elongation A (%) |
|---|---|---|
| ≥490 | ≥220 | ≥35 |
XM-19 (S20910) — Mechanical Properties (Annealed)
| Tensile Strength Rm (N/mm²) | Yield Strength Rp0.2 (N/mm²) | Elongation A (%) | Reduction of Area (%) |
|---|---|---|---|
| ≥690 | ≥380 | ≥35 | ≥50 |
XM-19 (S20910) — Cold-Worked Condition Properties
| Tensile Strength Rm (N/mm²) | Yield Strength Rp0.2 (N/mm²) | Elongation A (%) | Reduction of Area (%) | Bar Diameter (mm) |
|---|---|---|---|---|
| ≥930 | ≥725 | ≥20 | ≥50 | ≤2 (30–81) |
| ≥795 | ≥515 | ≥25 | ≥50 | (50.8) 3 (76.2) |
| ≥690 | ≥415 | ≥30 | ≥50 | (76.2)–8 (203.2) |
Side-by-Side Summary
| Property | 254 SMO (S31254) | 904L (N08904) | XM-19 (S20910) |
|---|---|---|---|
| UNS / ASTM | S31254 / A276 | N08904 / A276 | S20910 / A276 |
| Cr (%) | 19.5–20.5 | 19.0–23.0 | 20.5–23.5 |
| Ni (%) | 17.5–18.5 | 23.0–28.0 | 11.5–13.5 |
| Mo (%) | 6.0–6.5 | 4.0–5.0 | 1.5–3.0 |
| N (%) | 0.18–0.25 | ≤0.10 | 0.2–0.4 |
| Cu (%) | 0.50–1.0 | 1.0–2.0 | — |
| Special elements | — | — | Nb, V (microalloyed) |
| Tensile Strength (N/mm²) | ≥650 | ≥490 | ≥690 (annealed) |
| Yield Strength (N/mm²) | ≥300 | ≥220 | ≥380 (annealed) |
| Elongation (%) | ≥35 | ≥35 | ≥35 |
| Key strength | Pitting & crevice corrosion resistance (PREN >40) | Sulfuric acid & reducing acid resistance | High strength + good corrosion resistance |
| Typical applications | Seawater systems, FGD, chemical processing | Acid heat exchangers, pickling equipment | High-strength fasteners, shafting, marine |
Material Selection Guide
Choose 254 SMO (S31254) when:
- Your environment contains high chloride concentrations (seawater, brackish water, brine)
- Pitting and crevice corrosion are primary failure modes
- You need a PREN (Pitting Resistance Equivalent Number) above 40
- Applications include offshore platforms, desalination plants, flue gas desulfurization (FGD) systems, and pulp bleaching equipment
Choose 904L (N08904) when:
- Your process involves sulfuric acid, phosphoric acid, or other reducing acids
- High nickel content is needed for resistance to stress corrosion cracking
- Applications include acid heat exchangers, pickling tanks, chemical storage vessels, and pharmaceutical equipment
- Cost is a consideration vs. 6Mo grades — 904L offers good performance at a lower price point than 254 SMO
Choose XM-19 (S20910) when:
- High mechanical strength is the primary requirement alongside corrosion resistance
- You need a non-magnetic austenitic stainless with significantly higher yield strength than 316L
- Applications include high-strength fasteners, marine shafting, valve stems, and structural components in corrosive environments
- Cold-worked bar stock is acceptable — XM-19 achieves yield strengths up to 725 N/mm² in cold-worked condition
FULLERKREG Supply Capabilities
FULLERKREG supplies precision fasteners and engineered components in all three grades:
- Material Test Certificates (MTC) — EN 10204 3.1 / 3.2 available on request
- ASTM A276 / A193 / A194 compliance — for bolting and fastener applications
- Custom dimensions — non-standard bar diameters, thread forms, and head styles
- Bulk wholesale pricing — OEM and MRO procurement with competitive lead times
- Global shipping — from our manufacturing base in China to customers worldwide
Need a material recommendation or a quote for 254 SMO, 904L, or XM-19 fasteners? Contact FULLERKREG with your specification and our engineering team will respond promptly.
FULLERKREG — Precision Fasteners. Global Standards. Reliable Supply.