For Class A and D marine steel plate, the cleanliness requirements are S≤0.008, P≤0.015, S≤0.005%, P≤0.010% for Class E, S≤0.002%, P≤0.005% for Class F marine steel plate. In order to ensure NDT≤-550C for naval marine steel plate, S≤0.002%, P≤0.005%, N≤40ppm, O≤10ppm and H≤1.0ppm are required. The refining process is essential.
Class A marine steel plate and grade D marine steel plate can be delivered by hot rolling or controlled rolling. Class E and F marine steel plate can be used in normalizing or hot mechanical rolling condition.
The marine steel plate must distinguish the difference between controlled rolling and hot mechanical rolling. According to the current standard, Class E and Class F ship plates cannot be produced without heat treatment conditions.
The quality requirements of the marine steel plate also include the requirements of shape and dimensional accuracy, ultrasonic flaw detection and performance stability.
