254 SMO · ISO 9328-7
254 SMO is presented here as X1CrNiMoCuN20-18-7 (4547-312-54-I) under ISO 9328-7. Stainless steel flat products for pressure service, with chemical and room-temperature mechanical requirements.
X1CrNiMoCuN20-18-7
Designation: 4547-312-54-I
Data edition: ISO 9328-7:2018
254 SMO 4547-312-54-I
254 SMO is presented here as X1CrNiMoCuN20-18-7 (4547-312-54-I) under ISO 9328-7. Stainless steel flat products for pressure service, with chemical and room-temperature mechanical requirements.
Tables 3 and 4 define cast chemistry; Tables 9 and 10 define the displayed solution-annealed tensile properties. Duplex references share the ISO 4462 designation. Narrow-strip longitudinal proof strength is 15 MPa lower than the transverse values shown.
Related grades
12 material references with ISO 9328-7 data.
254 SMO properties
Select a table to compare requirements.
| Element | Mass % |
|---|---|
| C | ≤0.020 |
| Si | ≤0.70 |
| Mn | ≤1.00 |
| P | ≤0.030 |
| S | ≤0.010 |
| Cr | 19.5–20.5 |
| Ni | 17.5–18.5 |
| Mo | 6.0–7.0 |
| N | 0.18–0.25 |
| Other elements | Cu: 0.50–1.00 |
Composition in mass %. ≤ denotes a maximum; ≥ denotes a minimum; paired values are ranges. — means no numerical limit is provided in the cited data, not zero.
| Form | Thickness (mm) | Condition | Test direction | Rp0.2 (MPa) | Rp1.0 min (MPa) | Rm (MPa) | A80 min (%) | A min (%) | Other requirements |
|---|---|---|---|---|---|---|---|---|---|
| Cold-rolled strip | ≤8 | +AT | Transverse | 320 | 350 | 650–850 | 35 | 35 | — |
| Hot-rolled strip | ≤13.5 | +AT | Transverse | 300 | 340 | 650–850 | 35 | 35 | — |
| Hot-rolled plate | ≤75 | +AT | Transverse | 300 | 340 | 650–850 | 40 | 40 | — |
Room-temperature properties for the stated product form and condition. Proof strengths and elongation are minima unless a range is shown. A80 uses an 80 mm gauge length below 3 mm thickness; A uses 5.65√S₀ from 3 mm thickness. +AT means solution annealed. For austenitic strip below 300 mm width tested longitudinally, A80 is reduced by 5 percentage points and A by 2 points. For stretcher-levelled SS304, elongation minima are 5 points lower.