API 2H Gr.50 vs S355J2
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
API 2H Gr.50
Structural & HSLA Steel
API 2H Grade 50 is the offshore-structure plate specification: a normalized, fine-grain C-Mn steel with 345 MPa yield, −40 °C Charpy toughness and a capped carbon equivalent, written for welded jackets, decks and nodes that must survive North-Sea-class fatigue and low temperatures. Supplementary through-thickness (Z) and CTOD requirements are commonly invoked on top of the base spec.
Standards: DIN — (cf. EN 10225 S355G offshore grades) · AISI API 2H Gr.50
S355J2
Pipe & Tube Steel
S355J2 is Europe’s structural HSLA steel (EN 10025-2), the benchmark for welded structures, machinery and pipe where −20 °C toughness is specified.
Standards: DIN 1.0577 (S355J2) / 1.0570 legacy St52-3 · AISI A572 Gr.50 (near) · JIS SM490B (near) · GB Q345B (near)
Chemical composition compared (%)
| Element | API 2H Gr.50 | S355J2 |
|---|---|---|
| C | ≤0.18 | ≤0.20 |
| Si | 0.05–0.50 | ≤0.55 |
| Mn | 1.15–1.60 | ≤1.60 |
| P | ≤0.030 | ≤0.025 |
| S | ≤0.010 | ≤0.025 |
Properties compared
| Property | API 2H Gr.50 | S355J2 |
|---|---|---|
| Yield strength | ≥345 MPa | ≥355 MPa (≤16 mm) |
| Tensile strength | 483–620 MPa | 470–630 MPa |
| Impact | ≥41 J at −40 °C (transverse) | J2: −20 °C, ≥27 J |
| Carbon equivalent | CE(IIW) ≤0.43 typical spec cap | — |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: API 2H Gr.50 · S355J2. Substitution decisions for certified parts stay with the design authority.