Study And Development Of E40 High Strength Offshore Platform Steel

As more domestic wide heavy plate product lines have been on stream in succession, and the proposition that put forward by the government of turning all domestic product lines into high-level and advanced production bases in the world has put into practice, all medium and heavy plate enterprises are increasing input to the development of high additional value products, including the offshore platform steel. With the continuous development of the marine resources of our country, the requirement of high strength offshore platform steel has also been increased. To develop E40 high strength offshore platform steel, the author of this paper has performed the thermal simulation experiment and hot rolling in the laboratory. The main procedures and results involved are shown as follows:(1) Through the single press test, the stress-strain curve of the test steel is measured, the influence law of the deforming temperature, deforming rate and deforming degree on the stress of the steel is researched, and the mathematical model of resistance of deformation is established.(2)The behavior of dynamic softening of the test steel in austenitic area is researched through the analysis of strain-stress curve. The activation energy of dynamic recrystallization is 323.315 KJ/mol. The microstructural evolution of dynamic recrystallization under various deforming degree is researched by metallographic analysis.(3)The heat expansion method is used to test the CCT curves on both undeformed and deformed condition. The influence law of cooling rate and deforming degree on phase transformation and structure of the steel can be obtained through the metallographic analysis and hardness detection. The influence of deform processing parameter on ferrite transformation and bainite transformation is also studied.(4)Based on the thermal simulation experiment, the influence law of different processing parameter such as final temperature on structure and property of the test steel is researched through the hot rolling test in the laboratory, and meanwhile the mechanical property is also detected. Thus a rational process of producing E40 high strength offshore platform steel is obtained, which offer bases and references to set appropriate rolling and cooling processes for industrial production.(5)The influence of different processes on Z-direction property of the test steel is studied. The maximum contraction of tensile fracture of Z-direction tension is up to 60.31%. Fracture scanning and energy dispersion spectrum analysis are applied to the Z-direction samples. All these can offer technical reference to the research on Z-direction steel.