Development and Production Technology of Shipbuilding Steel Plate

Development and Production Technology of Shipbuilding Steel Plate

At present, the main varieties of wide and thick steel plate production include carbon structural steel plate, high quality carbon structural steel plate, low alloy high strength structural steel plate, shipbuilding steel plate, pipeline steel plate, engineering machinery steel plate, automobile girder plate, bridge plate, etc. Shipbuilding steel plate is one of the main special plate varieties for wide and heavy plates. China is a big shipbuilding country, and the demand for shipbuilding steel plate is keeping increasing. At the same time, the large-scale, high-speed ship and the development of marine oil and gas fields provide a broad application prospect for the application of high-strength hull structural steel, so it is necessary to do the research for the development trend and production technology of shipbuilding steel plate, especially the production control technology of high-strength shipbuilding steel plates.

Wide-thickness steel plate for shipbuilding includes general strength ship plate (AE), high strength ship plate (AH32 shipbuilding steel plate-EH40), ultra high strength ship plate steel (AH42-EH69), marine boiler plate, Z-direction steel plate for shipbuilding and offshore platforms, etc. . The main technology of shipbuilding steel production is changed from high carbon single element, low carbon multi-element to micro-alloying and composite micro-alloying. It develops from low-strength level to high-strength level and ultra-high-strength level. Currently, the strength of shipbuilding steel plate can generally reach 450MPa to 980MPa.

Since the organization determines the performance of steel, organizational control has always been the key to the development of shipbuilding steel plate production technology. Although the strength of the ferritic plus pearlite structure steel can be improved and the toughness is improved within a certain cooling range, the improvement and improvement are limited. Therefore, the development of steel of other organization types is an important way to obtain shipbuilding steel with good comprehensive mechanical properties. In recent years, domestic and foreign research results show that high carbon bainite steel has poor impact toughness and weldability despite its high strength. With the continuous development of smelting technology, it is found that the micro-carbon low-alloy steel not only has high strength, but also has low impact transition temperature and excellent welding performance, and these excellent comprehensive mechanical properties can be obtained under controlled rolling conditions.

Since shipbuilding steel plates require good low temperature impact toughness and low brittle transition temperature, it has requirements for aluminum content and microalloying for high strength shipbuilding steel plates. In order to ensure good welding performance, it is necessary to control the upper limit of carbon equivalent, and determine the composition control range of steel according to the comprehensive performance requirements of high-strength ship plates. The strengthening effect of microalloying elements should be considered for the choice of microalloying elements and it can not adversely affect the microstructure of steel. The influence of microalloying elements on the brittle transition temperature of steel is also an important factor should be considered. The influence of steel purity on the toughness of high-strength ship plates, especially low temperature toughness, is also the key to control in smelting.