Chemical composition and mechanical properties of SA387 Grade21, an American grade of pressure vessel steel.
SA387 Grade21 Approximate Grade Lookup Table
SA387 Grade21 Chemical Composition
| Element | Analysis Category |
Grade21 |
||||||||
| C | Smelting Analysis | 0.05-0.15A | ||||||||
| Finished Product Analysis | 0.04-0.15A | |||||||||
| Mn | Smelting Analysis | 0.30-0.60 | ||||||||
| Finished Product Analysis | 0.25-0.66 | |||||||||
| P,≤ | Smelting Analysis | 0.025 | ||||||||
| Finished Product Analysis | 0.025 | |||||||||
| S,≤ | Smelting Analysis | 0.025 | ||||||||
| Finished Product Analysis | 0.025 | |||||||||
| Si | Smelting Analysis | ≤0.50 | ||||||||
| Finished Product Analysis | ≤0.50 | |||||||||
| Cr | Smelting Analysis | 2.75-3.25 | ||||||||
| Finished Product Analysis | 2.63-3.37 | |||||||||
| Mo | Smelting Analysis | 0.90-1.10 | ||||||||
| Finished Product Analysis | 0.85-1.15 | |||||||||
| Ni | Smelting Analysis | ... | ||||||||
| Finished Product Analysis | ... | |||||||||
| V | Smelting Analysis | ... | ||||||||
| Finished Product Analysis | ... | |||||||||
| Nb | Smelting Analysis | ... | ||||||||
| Finished Product Analysis | ... | |||||||||
| B，≤ᶜ | ... | |||||||||
| N | Smelting Analysis | ... | ||||||||
| Finished Product Analysis | ... | |||||||||
| N/Al | ... | |||||||||
| Al，≤ᶜ | ... | |||||||||
| Ti，≤ᶜ | ... | |||||||||
| Zr，≤ᶜ | ... | |||||||||
| W，≤ᶜ | ... | |||||||||
| Cu，≤ᶜ | ... | |||||||||
| Sb，≤ᶜ | ... | |||||||||
| As，≤ᶜ | ... | |||||||||
| Sn，≤ᶜ | ... | |||||||||
A:For steel plates with a thickness greater than 5 inches (125 mm), the carbon content in the finished product analysis should not exceed 0.17%.
B:Cb and Nb are interchangeable and commonly used names for the same element, and both names are applicable to the (ASTM) "A101" standard.
C:Both smelting analysis and finished product analysis are applicable.
SA387 Grade21 Mechanical Properties
Tensile properties of Class I steel plates
| Tensile strength(MPa) | 415-585 | ||||||||||||
| Yield strength(MPa) | ≥205 | ||||||||||||
| Elongation (gauge length 8 in. or 200 mm), % | ... | ||||||||||||
| Elongation (gauge length 8 in. or 50 mm), % | ≥18 | ||||||||||||
| Reduction of area,% | ≥45② | ||||||||||||
| ≥40③ | |||||||||||||
①For adjustments to elongation, please refer to the A20/A20M standard.
②Measurement using a round sample.
③Determination using flat specimens.
Tensile properties of Class II steel plates
| Tensile strength(MPa) | 515-690 | ||||||||||||||
| Yield strength (0.2% residual deformation), MPa ≥ | 310 | ||||||||||||||
| Elongation (gauge length 8 in. or 200 mm), %≥ | ... | ||||||||||||||
| Elongation (gauge length 8 in. or 50 mm), %≥ | 18 | ||||||||||||||
| Reduction of area,% | ≥45③ | ||||||||||||||
| ≥40④ | |||||||||||||||
①Not applicable to annealed steel sheets
②For adjustments to elongation, please refer to the A20/A20M standard.
③Measurement using a round sample.
④Determination using flat specimens.
*Grade 91 steel plate is only applicable to Category 2 steel plates, see Section 1.3 — Translator's note