Difference between ABS FQ63 and ABS FQ70 steel plate

ABS FQ63 is an ultra-high-strength marine steel plate certified by the American Bureau of Shipping (ABS) for demanding offshore and shipbuilding applications. The "FQ" designation signifies that it is a quenched and tempered steel with impact toughness tested at the extremely low temperature of -60°C, ensuring exceptional performance in polar and Arctic environments. It has a minimum yield strength of 620 MPa and a tensile strength range of 720-890 MPa, with a minimum elongation of 15%. This grade offers excellent weldability and low-temperature impact resistance, making it ideal for offshore drilling platforms, ultra-large container vessels, and critical marine structures requiring maximum strength-to-weight ratio.

ABS FQ70 is an ultra-high-strength marine steel plate also certified by ABS, manufactured through quenching and tempering processes. Like FQ63, it is impact tested at -60°C, with minimum impact energy requirements of 41J (transverse) and 62J (longitudinal). The "70" denotes a minimum yield strength of 690 MPa and a tensile strength range of 770-940 MPa, with a minimum elongation of 14%. Its chemical composition is strictly controlled with carbon ≤0.18% and manganese ≤1.60%. This grade is designed for the most demanding load-bearing applications, including self-elevating drilling platforms, jack-up rig legs, and fire-resistant structural components where structural integrity during fire exposure is critical.

Both ABS FQ63 and ABS FQ70 are ABS-certified quenched and tempered marine steels with exceptional low-temperature toughness tested at -60°C, ensuring reliable performance in the most extreme Arctic and harsh marine environments. Their primary difference lies in strength level: FQ63 offers a minimum yield strength of 620 MPa with tensile strength of 720-890 MPa, while FQ70 provides a substantially higher minimum yield strength of 690 MPa with tensile strength reaching 770-940 MPa. Both grades feature strictly controlled chemical composition (carbon ≤0.18%) and maintain good weldability for critical marine service. The selection between them depends on whether the project requires the high strength of FQ63 or the superior performance of FQ70 for more extreme structural demands, including fire-resistant applications.

Chemical Composition

Mechanical Property