GB 712-2000 Ship Structural Steel
GB 712-2000 is the Chinese classification society’s standard for ship structural steel. This standard defines the requirements and chemical and mechanical properties of the steel grades used in shipbuilding. It also contains test methods and metallurgical processes used in forging, hot rolling, cold rolling, heat treatment, welding, and other related technologies.
ABS grade A, B, D and E are covered in this standard, with the chemical and mechanical properties detailed below. All the grades are normalized.
ABS Grade A:
Grade A steel is a structural steel that provides moderate strength and good formability. It is easy to weld and is used where the strains of welding are not too severe. It also has good corrosion resistance properties, making it suitable for use in a variety of environments. The chemical composition of this steel is C 0.18-0.23, Si 0.15-0.45, Mn 0.6-1.00, P 0.035, S 0.035, and Cr 0.25-0.55. Its yield strength is 235 MPa, and its tensile strength is 400-520 MPa.
ABS Grade B:
Grade B steel is an improved form of Grade A steel, providing greater strength and higher yield strength. Its chemical composition is C 0.23-0.28, Si 0.15-0.45, Mn 0.6-1.00, P 0.035, S 0.035, and Cr 0.25-0.55. Its yield strength is 300 MPa, and its tensile strength is 440-590 MPa.
ABS Grade D:
Grade D steel is another improved form of Grade A steel, providing greater strength and higher yield strength. Its chemical composition is C 0.27-0.32, Si 0.15-0.45, Mn 0.6-1.00, P 0.035, S 0.035, and Cr 0.25-0.55. Its yield strength is 355 MPa, and its tensile strength is 490-620 MPa.
ABS Grade E:
Grade E steel is an improved form of Grade D steel, providing even greater strength and higher yield strength. Its chemical composition is C 0.32-0.37, Si 0.15-0.45, Mn 0.6-1.00, P 0.035, S 0.035, and Cr 0.25-0.55. Its yield strength is 390 MPa, and its tensile strength is 520-640 MPa.
All the grades covered in this standard are normalized. Normalizing is a heat treatment process in which the steel is heated to a specific temperature before cooling, which increases its toughness and strength by allowing for a more uniform grain size and distribution in the material.
ABS Grade A, B, D, and E are all widely used in shipbuilding and other marine applications. They are all ferritic steels, which means they are strong, ductile, and can resist corrosion in a variety of environments. They are also relatively easy to work with, making them a popular choice for shipbuilders. They offer good welding and forming capabilities, as well as excellent corrosion resistance, making them suitable for a wide range of applications.
