Technical specification of steel according to ASTM A131/A131M standard
The ASTM A131/A131M standard establishes strict requirements for rolled metal products (plates, shapes, and bars) made of structural steels optimized for the shipbuilding industry. This standard covers a wide range of grades that EV Group China supplies for the construction of marine vessels and offshore structures.
Materials are classified by strength level:
- Ordinary strength (yield strength 235 MPa): Grades A, B, D, CS, and E.
- High strength (yield strength from 315 to 390 MPa): Grades AH, DH, EH, and FH.
The production of shaped rolled products and bars is primarily focused on grades A, B, AH32, and AH36. Supply of products from other steel grades is carried out upon individual agreement between the customer and EV Group China engineers.
Heat treatment regimes are regulated based on the size and thickness of A131 rolled products. Plate products undergo mandatory normalization or thermo-mechanical processing. For shapes and bars, combined rolling and heat treatment are applied to achieve the specified characteristics. The standard limits the maximum thickness of products:
- Sheet metal: up to 100 mm (4 inches).
- Shapes and bars: up to 50 mm (2 inches).
Welding technology is selected individually for each grade, taking into account operational loads and the requirements of the ASTM A6/A6M standard, which details recommendations for welding processes.
Quality control carried out by EV Group China includes:
- Thermal analysis of chemical composition to confirm compliance with the grade standard.
- Metallographic analysis to evaluate average grain size, which is critical for steel toughness in low-temperature conditions.
- Mechanical testing: tensile testing and Charpy V-notch impact toughness testing.