Stainless steel.
A broad family of corrosion-resistant steels whose grade, product form, condition and specification must be considered together.
More than one corrosion-resistant alloy.
Stainless steels are commonly grouped by microstructure: austenitic, ferritic, martensitic, precipitation-hardening and duplex. Each family balances corrosion resistance, strength, fabrication, temperature capability and cost differently.
The final selection should be controlled by the applicable standard, product form, required condition, environment and fabrication route.
Stainless steel by supply route.
| Product route | Representative grades | Typical application context |
|---|---|---|
| Plates, Sheets & Coils ↗ | 304L, 316L, 321, 347, 904L, 430, 17-4PH | Tanks, vessels, heat-transfer surfaces, cladding and fabricated assemblies |
| Pipes & Tubes | 304L, 316L, 321, 347; duplex grades where specified | Process piping, heat exchangers, instrumentation and hygienic systems |
| Bars & Long Products | 304, 316, 410, 431, 17-4PH, 15-5PH, XM-19 | Shafts, valve parts, fasteners, precision machining and structural members |
| Flanges, Fittings & Forgings | F304/L, F316/L, F321, F347 and application-specific stainless forging grades | Pressure piping, equipment connections, rings, hubs and forged components |
| Fasteners | B8 / B8M, 304 / 316 fastener grades, A286 and precipitation-hardening grades | Pressure joints, structures, machinery and higher-strength assemblies |
| Welding & Wire Products | ER308L, ER316L, 304 / 316 wire, spring and specialist grades | Fabrication, joining, filtration, screening, springs and formed wire products |
Product and application relationships are preliminary guidance. Confirm grade, condition, product specification, fabrication route and service environment.
Common stainless grade map.
| Family | Common designation | UNS | EN number | Typical product context |
|---|---|---|---|---|
| Austenitic | 201 | S20100 | 1.4372 | Sheet, coil, strip and formed products |
| Austenitic | 202 | S20200 | 1.4373 | Sheet, coil and formed products |
| Austenitic | 301 | S30100 | 1.4310 | Sheet, strip and work-hardened products |
| Austenitic | 304 | S30400 | 1.4301 | Flat, long, tubular, forged and fabricated forms |
| Austenitic | 304L | S30403 | 1.4307 | Low-carbon welded construction |
| Austenitic | 304H | S30409 | 1.4948 | Elevated-temperature pressure applications |
| Austenitic | 305 | S30500 | 1.4303 | Deep drawing and formed products |
| Heat resistant austenitic | 309S | S30908 | 1.4833 | High-temperature sheet and plate |
| Heat resistant austenitic | 310S | S31008 | 1.4845 | Oxidation-resistant high-temperature service |
| Austenitic | 316 | S31600 | 1.4401 | Mo-alloyed corrosion-resistant products |
| Austenitic | 316L | S31603 | 1.4404 | Low-carbon Mo-alloyed welded construction |
| Austenitic | 316Ti | S31635 | 1.4571 | Titanium-stabilized elevated-temperature or welded service |
| Austenitic | 317L | S31703 | 1.4438 | Higher-molybdenum corrosion-resistant products |
| Austenitic | 321 | S32100 | 1.4541 | Titanium-stabilized sheet, plate, pipe and components |
| Austenitic | 347 | S34700 | 1.4550 | Niobium-stabilized elevated-temperature service |
| Super austenitic | 904L | N08904 | 1.4539 | Severe corrosion environments |
| Ferritic | 409 | S40900 / S40910 | 1.4512 | Heat-resistant sheet and exhaust-related fabrication |
| Ferritic | 430 | S43000 | 1.4016 | Sheet, strip, decorative and formed products |
| Ferritic | 439 | S43035 | 1.4510 | Stabilized sheet and tubular applications |
| Ferritic | 441 | S44100 | 1.4509 | Stabilized heat-resistant sheet |
| Ferritic | 444 | S44400 | 1.4521 | Mo-alloyed ferritic corrosion-resistant products |
| Martensitic | 410 | S41000 | 1.4006 | Heat-treatable plate, bar, forgings and components |
| Martensitic | 420 | S42000 | 1.4021 / 1.4034 | Hardness and wear-oriented components |
| Martensitic | 431 | S43100 | 1.4057 | High-strength corrosion-resistant shafts and components |
| Martensitic | 440A | S44002 | 1.4109 | Hardened wear and cutting applications |
| Martensitic | 440B | S44003 | 1.4112 | Higher-carbon hardened components |
| Martensitic | 440C | S44004 | 1.4125 | High-hardness bearings and wear components |
| Precipitation hardening | 17-4PH | S17400 | 1.4542 | High-strength bar, plate, forgings and machined parts |
| Precipitation hardening | 15-5PH | S15500 | 1.4545 | High-strength aerospace and engineered components |
| Precipitation hardening | 13-8Mo | S13800 | 1.4534 | High-strength critical components |
| Precipitation hardening | 17-7PH | S17700 | 1.4568 | Sheet, strip, springs and formed parts |
| Nitrogen strengthened | XM-19 / Nitronic 50 | S20910 | 1.3964 | High-strength corrosion-resistant bar and components |
Designation relationships are purchasing guides, not automatic equivalence declarations. Confirm chemistry, condition, product specification and required properties on the order.
| Grade | C max | Cr | Ni | Mo | Other principal elements |
|---|---|---|---|---|---|
| 304L | 0.030 | 18.0-20.0 | 8.0-12.0 | - | Mn 2.0 max; Si 0.75 max |
| 316L | 0.030 | 16.0-18.0 | 10.0-14.0 | 2.0-3.0 | Mn 2.0 max; Si 0.75 max |
| 321 | 0.080 | 17.0-19.0 | 9.0-12.0 | - | Ti stabilized |
| 347 | 0.080 | 17.0-19.0 | 9.0-13.0 | - | Nb + Ta stabilized |
| 904L | 0.020 | 19.0-23.0 | 23.0-28.0 | 4.0-5.0 | Cu 1.0-2.0 |
| 430 | 0.120 | 16.0-18.0 | - | - | Ferritic chromium grade |
| 410 | 0.15 | 11.5-13.5 | - | - | Martensitic chromium grade |
| 17-4PH | 0.070 | 15.0-17.5 | 3.0-5.0 | - | Cu 3.0-5.0; Nb + Ta 0.15-0.45 |
| 15-5PH | 0.070 | 14.0-15.5 | 3.5-5.5 | - | Cu 2.5-4.5; Nb + Ta 0.15-0.45 |
| 13-8Mo | 0.050 | 12.25-13.25 | 7.5-8.5 | 2.0-2.5 | Al 0.90-1.35 |
| XM-19 | 0.060 | 20.5-23.5 | 11.5-13.5 | 1.5-3.0 | Mn 4.0-6.0; N 0.20-0.40; Nb 0.10-0.30 |
| Product form | Common ASTM / ASME route | Common EN route |
|---|---|---|
| Plate, sheet and strip | ASTM A240/A240M; ASME SA-240; ASTM A480/A480M | EN 10088-2 |
| Bars and shapes | ASTM A276/A276M; ASTM A479/A479M; ASTM A484/A484M | EN 10088-3; EN 10272 |
| Forgings and forged fittings | ASTM A182/A182M; ASME SA-182 | EN 10222-5 |
| Seamless and welded pipe | ASTM A312/A312M; ASME SA-312; ASTM A358/A358M | EN 10216-5; EN 10217-7 |
| Heat-exchanger and condenser tube | ASTM A213/A213M; ASTM A249/A249M | EN 10216-5; EN 10217-7 |
| Pressure-vessel plate | ASTM A240/A240M; ASME SA-240 | EN 10028-7 |
| PH stainless flat products | ASTM A693 | Grade- and condition-specific EN product route |
| Fasteners | ASTM F593; ASTM F594; ASTM A193/A193M; ASTM A194/A194M | EN ISO 3506 series or application-specific route |
Technical data is provided for preliminary sourcing guidance. The applicable customer specification, drawing, purchase order and latest standard revision govern each requirement.
Grade, form and condition must agree.
A grade designation alone does not define an acceptable supply. Confirm product standard, dimensions, heat treatment or temper, surface, mechanical properties, corrosion tests, NDE, inspection documentation, marking and traceability.
Where equivalents are proposed, the comparison must cover the complete specification and application rather than only a familiar grade name.
Move from material to supply route.
Send the grade, form and specification.
Include condition, dimensions, quantity, inspection, documentation and delivery requirements.
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