What are difference between ABS FQ47 and ABS FQ70 steel plate？

ABS FQ47 is an extra-high-strength marine steel plate certified by the American Bureau of Shipping (ABS) . The "FQ" designation signifies it is a quenched and tempered steel with impact toughness tested at -60°C, ensuring exceptional performance in polar and Arctic environments . It has a minimum yield strength of 460 MPa and a tensile strength ranging from 570 to 720 MPa, with a minimum elongation of 17% . Impact energy requirements are 31J (transverse) and 46J (longitudinal) at -60°C . This grade is widely used for offshore drilling platforms, hull structures, and critical marine components requiring excellent low-temperature toughness and weldability.

ABS FQ70 is an ultra-high-strength marine steel plate also certified by ABS, manufactured through quenching and tempering processes . Like FQ47, it is impact tested at -60°C, with impact energy requirements of 41J (transverse) and 62J (longitudinal) at this temperature . The "70" denotes a minimum yield strength of 690 MPa and a tensile strength ranging from 770 to 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 applications, including jack-up rig legs, ultra-large container vessels, and fire-resistant structural components where structural integrity during fire exposure is critical.

Both ABS FQ47 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: FQ47 offers a minimum yield strength of 460 MPa with tensile strength of 570-720 MPa, suitable for high-strength offshore platforms and ship hulls, while FQ70 provides a substantially higher minimum yield strength of 690 MPa with tensile strength reaching 770-940 MPa, designed for the most demanding load-bearing applications requiring maximum strength-to-weight ratio and fire resistance . Both grades feature strictly controlled chemical composition (carbon ≤0.18%, manganese ≤1.60%) and maintain good weldability for critical marine service.

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