Difference between ABS EQ51 and ABS EQ63 steel plate

ABS EQ51 is an ultra-high-strength marine steel plate certified by the American Bureau of Shipping (ABS) , produced through quenching and tempering (Q&T) . The "E" designation signifies it is impact tested at -40°C . It has a minimum yield strength of 500 MPa (73 ksi) and tensile strength ranging from 610 to 770 MPa (88-112 ksi), with minimum elongation of 16% . Impact energy requirements are minimum 50J (longitudinal) or 33J (transverse) at -40°C. This grade is widely used in offshore drilling platforms, ship hulls, and critical marine structures .

ABS EQ63 is an ultra-high-strength marine steel plate also certified by ABS, manufactured using quenching and tempering (Q&T) processes . The "63" denotes a minimum yield strength of 620 MPa (90 ksi) and tensile strength ranging from 720 to 890 MPa (104-129 ksi), with minimum elongation of 15% . Impact testing is performed at -40°C, with minimum energy requirements of 62J (longitudinal) or 41J (transverse) . The chemical composition is strictly controlled with carbon ≤0.20% and manganese ≤1.70% . This grade is designed for the most demanding offshore structures, including drilling platforms, jack-up rig legs, and floating production storage vessels (FPSOs).

Both ABS EQ51 and ABS EQ63 are ABS-certified ultra-high-strength marine steels produced by quenching and tempering, with excellent low-temperature toughness tested at -40°C for reliable performance in harsh marine environments . Their primary difference lies in strength level: EQ51 offers a minimum yield strength of 500 MPa with tensile strength of 610-770 MPa, suitable for high-strength offshore platforms and shipbuilding , while EQ63 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 strength-to-weight ratio. Both grades feature controlled chemical composition and maintain good weldability for critical marine structural applications.

Chemical Composition

Mechanical Property