Research On The Weldability Simulation Of X80 Pipeline Steel

High-pressure, large-diameter and high-strength pipes are inevitable trend for the oil and natural gas transporting pipeline. X80 pipeline steel, microalloyed steel produced by TMCP process with high strength and good crack- resistance prosperity, is the main material of transporting pipeline. In this paper, physical simulation and quantitative predication of CGHAZ for X80 pipeline steel were preformed in order to study its mechanical properties, which will provide theoretical knowledge for its practical application. At the same time, On the basis of heat transfer, metal physics and mechanics, the distribution of temperature, microstructure and stress could be calculated in order to optimize chemical composition and welding condition and predict microstructure and mechanical properties.SYSWELD software and double ellipsoid heat source were adopted to perform FEM simulation. Thermal cycle has been gained to reveal the relationship between weld condition and t8/5, tH.Three field of temperature, microstructure and stress were coupled considering the nonlinear relationship between material properties and temperature, and the interaction among temperature, microstructure and stress.Thermal simulating technology was used to study weld HAZ of pipeline steel X80. Based on the results of thermal simulation, the quantitative relationship between welding condition and properties of HAZ has been established. By optimization method and MATLAB, the most suitable weld condition which could lead to highest toughness of X80 pipeline steels has been determined.