Difference between ABS DQ51 and ABS DQ70 steel plate

ABS DQ51 is an extra-high-strength marine steel plate certified by the American Bureau of Shipping (ABS) , produced through quenching and tempering (Q&T) . The "DQ" designation signifies it is quenched and tempered with impact toughness tested at -20°C . It has a minimum yield strength of 500 MPa and tensile strength ranging from 610 to 770 MPa, with minimum elongation of 16% . Impact energy requirements are minimum 50J (longitudinal) or 33J (transverse) at -20°C. This grade is widely used in offshore drilling platforms, shipbuilding, and marine structures requiring high strength and toughness.

ABS DQ70 is an ultra-high-strength marine steel plate also certified by ABS, produced through quenching and tempering (Q&T) . The "70" denotes a minimum yield strength of 690 MPa and tensile strength ranging from 770 to 940 MPa, with minimum elongation of 14% . Impact testing is performed at -20°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 rigs, and critical marine engineering projects requiring maximum strength-to-weight ratio.

Both ABS DQ51 and ABS DQ70 are ABS-certified, quenched and tempered high-strength marine steels with excellent toughness tested at -20°C, ensuring reliable performance in harsh marine environments . Their primary difference lies in strength level: DQ51 offers a minimum yield strength of 500 MPa with tensile strength of 610-770 MPa, suitable for high-strength offshore platforms and shipbuilding , while DQ70 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 in critical offshore structures. Both grades feature controlled chemical composition and maintain good weldability for critical marine structural applications.

Chemical Composition

Mechanical Property