347 / X6CrNiNb18-10
1.4550Niobium-stabilized austenitic stainless steel. Nb forms NbC instead of CrC, preventing sensitization during welding or high-temp service (425-860°C). Alternative to 321 (Ti-stabilized). Used for welded structures in chemical processing, aircraft exhaust systems, and high-temp piping.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 347 | S34700 | REF |
| 🇪🇺 | EN | Europe | X6CrNiNb18-10 | 1.4550 | 100% |
| 🇯🇵 | JIS | Japan | SUS347 | — | 97% |
Sources: ASTM A240, EN 10088-2, JIS G4305
Chemical composition comparison (wt%)
Side-by-side: 347 / X6CrNiNb18-10 (EN) (EN 10088-2) vs SUS347 (JIS)
| Element | 347 / X6CrNiNb18-10 (EN) | SUS347 (JIS) | Overlap |
|---|---|---|---|
| C | 0–0.08% | — | — |
| Si | 0–1% | — | — |
| Mn | 0–2% | — | — |
| P | 0–0.045% | — | — |
| S | 0–0.015% | — | — |
| Cr | 17–19% | — | — |
| Ni | 9–12% | — | — |
| Nb | 0–1% | — | — |
Mechanical properties
Solution Treated
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 500–700 | MPa |
| Yield Strength | ≥ 190 | MPa |
| Elongation | ≥ 40 | % |
| Hardness HB | ≤ 215 | HB |
| Elastic Modulus | ≥ 200 | GPa |
| Density | ≥ 7.92 | g/cm3 |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| solution_treating | 1020–1100 °C | water | Rapid cooling required | Nb stabilization prevents sensitization in 425-860°C range |
Compatibility verdict
347 / X6CrNiNb18-10 and SUS347: 97% composition match
Close equivalents but NOT identical.
Related materials
304 Stainless Steel
1.4301The most widely used austenitic stainless steel. Excellent corrosion resistance, good formability and weldability. Standard choice for food processing, chemical, and architectural applications.
316L
1.4404Low-carbon austenitic stainless steel with molybdenum addition. Superior corrosion resistance to 304, especially against chlorides and pitting. Standard choice for chemical processing, marine, medical implants, and pharmaceutical equipment.
430 Stainless Steel
1.4016Ferritic chromium stainless steel with good corrosion resistance and formability. Lower cost than austenitic grades. Used for automotive trim, kitchen sinks, architectural panels, and appliance components.
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