Difference between ABS FQ70 and CCS F690 steel plate

ABS FQ70 and CCS F690 are both extra-high-strength steel plates designed for marine and offshore engineering applications. While they serve similar purposes and share comparable mechanical properties, they are certified by different classification societies-ABS (American Bureau of Shipping) and CCS (China Classification Society), respectively .

ABS FQ70 is an extra-high-strength steel plate certified by the American Bureau of Shipping. The designation "FQ70" indicates a minimum yield strength of 690 MPa and a tensile strength range of 770-940 MPa . The "F" denotes its impact test temperature of -60°C, requiring excellent low-temperature toughness . This grade is typically supplied in a quenched and tempered (QT) condition to achieve its mechanical properties . It is widely used in the construction of offshore drilling rigs, platforms, ice-class vessels, and critical marine structures operating in harsh environments .

CCS F690 (also referred to as FH690) is the equivalent grade certified by the China Classification Society. It shares identical mechanical property requirements: minimum yield strength of 690 MPa, tensile strength of 770-940 MPa, and Charpy V-notch impact testing at -60°C . Like its ABS counterpart, F690 is produced using controlled heat treatment processes such as quenching and tempering or thermomechanical control processing (TMCP) . It is commonly used in hull structures, superstructures, and offshore platform components .

Key Differences:
The primary distinction between these two grades lies in their certifying authority and the corresponding quality control system . While their chemical compositions and mechanical properties are nearly identical-both feature maximum carbon content of 0.18% and similar alloying elements-the difference is that ABS FQ70 complies with American Bureau of Shipping rules, whereas CCS F690 complies with China Classification Society rules . In practical terms, these steels are often considered interchangeable from a technical perspective, and many manufacturers can produce plates certified by both societies simultaneously . 

Chemical Composition

Mechanical Property

CCS F690 extra high strength property in Tempering and Quenching