Difference between CCS FQ47 and CCS FQ63 steel plate

CCS FQ47 is an extra-high-strength marine steel plate certified by the China Classification Society (CCS) . The "FQ" designation signifies that it is a quenched and tempered steel with impact toughness tested at -60°C, ensuring exceptional performance in Arctic and polar environments . It has a minimum yield strength of 460 MPa (67 ksi) and tensile strength ranging from 570 to 720 MPa (83-104 ksi) . Minimum elongation is typically 17% . The chemical composition is strictly controlled, with carbon equivalent (Ceq) limits to ensure good weldability . This grade is designed for critical structural components in offshore drilling rigs, icebreakers, and Arctic-class vessels.

CCS FQ63 is an ultra-high-strength marine steel plate also certified by CCS, manufactured through quenching and tempering (QT) . The "63" denotes a minimum yield strength of 620 MPa and tensile strength ranging from 720 to 890 MPa, with minimum elongation of 15% . Like FQ47, it is impact tested at -60°C, with minimum impact energy requirements typically around 46J (transverse) and 69J (longitudinal) . The chemical composition is precisely controlled, with a low carbon content to enhance weldability while maintaining high strength . This grade is designed for the most demanding applications such as self-elevating drilling platforms, ultra-large container ships, and critical marine structures requiring maximum strength-to-weight ratio.

Both CCS FQ47 and CCS FQ63 are CCS-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 ice-class vessels , while FQ63 provides a substantially higher minimum yield strength of 620 MPa with tensile strength reaching 720-890 MPa, designed for the most demanding load-bearing applications requiring maximum weight reduction . Both grades feature strictly controlled chemical composition and maintain good weldability for critical marine service.

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Mechanical Property