Knuckle boom cranes are mainly used in the field of ocean engineering, installed on decks or docks, and must work in harsh marine environments, so their quality and performance requirements are extremely high. To manufacture knuckle boom offshore cranes, the first step is to start by selecting materials. All materials must be certified by a classification society and have traceability. The plates for offshore cranes need to be made of high-strength and corrosion-resistant steel, because in the ocean, seawater has strong corrosiveness. If the materials are not up to standard, the crane will quickly be corroded and damaged, which cannot satisfy customer expectations.