What is the difference between AH36 and DH36?

AH36 and DH36 are both high-strength shipbuilding steel grades specified by the American Bureau of Shipping (ABS). While they share some similarities, there are key differences between AH36 and DH36:

Chemical Composition:

AH36: The chemical composition of AH36 includes a maximum carbon content of 0.18%, manganese content ranging from 0.90-1.60%, and a maximum phosphorus and sulfur content of 0.035% each.

DH36: DH36 has a similar chemical composition to AH36, with a maximum carbon content of 0.18%, manganese content ranging from 0.90-1.60%, and maximum phosphorus and sulfur content of 0.035% each.

Tensile Strength:

AH36: The minimum tensile strength of AH36 is 490-620 MPa (megapascals), depending on the thickness of the material.

DH36: DH36 also has a minimum tensile strength of 490-620 MPa, similar to AH36, with the variation based on material thickness.

Yield Strength:

AH36: The minimum yield strength of AH36 is 355 MPa.

DH36: DH36 also has a minimum yield strength of 355 MPa, matching AH36.

Charpy V-Notch Impact Test:

AH36: AH36 undergoes a Charpy V-notch impact test at -20°C (-4°F) and has a minimum average energy value of 34 Joules at that temperature.

DH36: DH36 is required to pass a Charpy V-notch impact test at -20°C (-4°F) as well, with a minimum average energy value of 34 Joules.

In summary, AH36 and DH36 are both high-strength shipbuilding steel grades with similar chemical compositions, minimum yield strengths, and Charpy V-notch impact test requirements. The key difference lies in the specified tensile strength range, which can vary depending on the thickness of the material. It's important to consult the specific standards and specifications, such as ABS rules and guidelines, for precise information when selecting between AH36 and DH36 for shipbuilding applications.