The yield strength (not less than 235N/mm^2) of these four grades of steel is the same as the tensile strength (400-520N/mm^2), but the impact energy at different temperatures is different.

High-strength hull structural steel is divided into strength grades according to its minimum yield strength, and each strength grade is divided into A, D, E, F4 grades according to its impact toughness.

The yield strength of A32, D32, E32, and F32 is not less than 315N/mm^2, and the tensile strength is 440-570N/mm^2. Impact toughness at -40 degree , -60 degree ;

The yield strength of A36, D36, E36, F36 is not less than 355N/mm^2, tensile strength is 490-620N/mm^2. A, D, E and F represent the impact toughness that can be achieved at 0 degree , -20 degree , -40 degree , and -60 degree respectively;

The yield strength of A40, D40, E40, and F40 is not less than 390N/mm^ 2. The tensile strength is 510-660N/mm^2, and A, D, E, and F represent the impact toughness that can be achieved at 0 degree , -20 degree , -40 degree , and -60 degree respectively.