Difference between BV AH32 and BV DH32

BV AH32 and BV DH32 are high-strength hull structural steel plates certified by Bureau Veritas (BV), designed for shipbuilding and marine applications. Both grades share a minimum yield strength of 315 MPa (as indicated by "32", which corresponds to 32 ksi yield strength). They are used in critical structural members of vessels where increased strength allows for weight reduction. The key distinction between them lies in their minimum service temperature grades, denoted by the prefix "A" or "D".

Key Differences

The fundamental difference is their impact toughness at low temperatures. The "A" in AH32 designates that the material's impact toughness is tested at 0°C (32°F), making it suitable for general oceangoing vessels operating in moderate climates. In contrast, the "D" in DH32 signifies a lower service temperature threshold, requiring impact testing at -20°C (-4°F). This makes BV DH32 steel suitable for ships operating in colder waters, such as the North Atlantic, where enhanced resistance to brittle fracture is required. To achieve this improved low-temperature toughness, DH32 typically involves stricter control of chemical composition and steelmaking practice (like fine grain treatment). Therefore, the selection criterion is the operational environment: BV AH32 is for general high-strength applications, while BV DH32 is specified for high-strength applications in cold climate service.

Chemical Composition

Mechanical Property