Chemical composition and mechanical properties of SA516Gr55 an American grade of  pressure vessel steel.

SA516Gr55 Approximate Grade Lookup Table

SA516Gr55 Chemical Composition

Element Thickness Grade55
C①② Plate thickness≤1/2in.(12.5mm) ≤0.18
Plate thickness＞1/2-2in.(12.5mm) ≤0.20
Plate thickness＞2-4in.(50-100mm) ≤0.22
Plate thickness＞4-8in.(100-200mm) ≤0.24
Plate thickness＞8in.(200mm) ≤0.26
Mn② Plate thickness≤1/2in.(12.5mm) Smelting Analysis 0.60-0.90
Finished Product Analysis 0.55-0.98
Plate thickness＞1/2in.(12.5mm) Smelting Analysis 0.60-1.20
Finished Product Analysis 0.55-1.30
P①* ≤0.025
S①* ≤0.025
Si Smelting Analysis 0.15-0.40
Finished Product Analysis 0.13-0.45

①Both smelting analysis and finished product analysis are applicable.

②For every 0.01% decrease below the specified maximum carbon content, the upper limit of the specified maximum manganese content can be increased by 0.06%, with a maximum allowable limit of 1.50% for smelting analysis and a maximum allowable limit of 1.60% for finished product analysis.

③For grade 60 steel plates with a thickness not exceeding 1/2 in. (12.5 mm), the manganese content can be 0.85%-1.20% according to smelting analysis and 0.79%-1.30% according to finished product analysis.

*The content of P and S was changed from ≤0.035 to ≤0.025 in the 2017 version.

SA516Gr55 Mechanical Properties

Tensile strength（MPa） 380-515
Yield strength（MPa） ≥205
Elongation (gauge length 8 in. or 200 mm), %② ≥23
Elongation (gauge length 2 in. or 50 mm), %② ≥27

①The 0.2% residual deformation method or the 0.5% elongation under load method can be used for determination.

②For adjustments to elongation, please refer to the A20/A20M standard.