| In order to improve the efficiency and reduce the cost, the transporting pipeline for oil and natural gas has rapidly developed to large diameter, high pressure and density. As the steel grade improved, the requirements for mechanical properties and weld ability are also enhanced. However, the higher the level of steel strength, the higher H2S corrosion resistance demands, this reality requires us to develop resistance to H2S corrosion of steel.Based on the research platform for Oil and Gas with the X65-X80pipeline steel high-level development of the state key Laboratory of Rolling and Automation (Northeastern University) and one Steel Corporation, this paper has mainly studied the effect of Thermo Mechanical Control Process (TMCP) of X70/80steel on the products’mechanical properties and hydrogen induced cracking (HIC). Therefore, with the thermo-mechanical simulation and experimental rolling, the effect of the different cooling methods on the microstructure and mechanical properties has been researched, and its resistance to hydrogen induced cracking (HIC) properties and welding properties has also been analyzed, the expected goals were reached. Additionally, it is also in the process of heavy plate rolling three-dimensional mathematical model of rolling force were derived. The main contents of the article include the following:(1) The single-pass compression was tested for the experimental steels. The activation energy of dynamic recrystallization was calculated. The influence of the deforming temperature, strain value and strain rate on the flow stress were investigated, and the mathematical models of deformation resistance were also established. The CCT curves of tested steels were also obtained under different deformation conditions and cooling rates.(2) The effect of deformation and cooling on the microstructure and mechanical properties of tested steels were studied for the industry trials.(3) According to NACE TM0284-2003and GB/T8650-2006"pipeline steel and pressure vessel cracking resistant steel determination" assessment method of X70/80cracking (HIC-resistant) performance.(4) The simulated weld test was carried out with the different lines of energy and peak temperature, the properties of X80pipeline steel welding were studied, spot welding for the next step to provide a theoretical basis.(5) A three-dimensional velocity field for plate rolling was proposed by global weighted method. Then, using the field and the linear MY (mean yield) criterion, the power functional of internal deformation for plate rolling was analyzed; using the collinear vectors, the power functional of friction was analyzed, ultimately, analytical solution of plate rolling power functional was obtained. |
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