This specification covers high-strength low-alloy structural steel plates intended for use in welded construction of naval ships where a savings in weight (mass) is important. The steel shall be made to fine grain practice. The plates shall optionally undergo heat treatment such as quenching or tempering to meet the requirements on mechanical properties such as yield point, yield strength, elongation, and Charpy V-notch impact, provided that the treatment be reported on the test report. The specimen shall undergo heat and product analyses and conform to the chemical composition values of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, vanadium, columbium, aluminum, titanium, and nitrogen.

1.1 This specification covers high-strength low-alloy structural steel plate intended for use in welded construction of naval ships where a savings in weight [mass] is important. Plates that conform to this specification offer improved weldability, formability, and toughness resulting from the specified alloying elements with limitations on carbon, sulfur, and residual element contents. Grades 50 and 65 may be provided as-rolled, control-rolled, thermo-mechanical control processed (including accelerated cooling), normalized, or quenched and tempered as required to meet the specified mechanical requirements.

1.2 The maximum thickness or weight [mass] of plates shall be as follows:

    Grade

Plate thickness,
max, in. [mm]

Plate weight [mass],
max, lb/ft² [kg/m²]

     50

2 [50]   

81.7 [393]

     65

2¹/₂ [65]

102 [502]

1.3 If the steel is to be welded, it is presupposed that a welding procedure suitable for the grade of steel and intended use or service will be utilized.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not necessarily exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.