Research On The Microstructure Performance And Crystal Orientation Of X80Pipeline Steel

As an economy, security, uninterrupted long-distance transmission tool, Pipeline steelsare used to transport oil and gas. Along with the throughput and conveying distance raising,the transport pipeline for oil and natural gas has rapidly developed to large diameter and highpressure. X80pipeline steel is becoming the main timber of the China’s WestEast Gas Pipeline Project. Along with the high grade pipeline steel widely used, for theurgent needs of high toughness pipeline steel and improving their transmission capacity,establishing objective material mechanical properties and more effective safety analysis ofpipeline steel has become urgent problem to be solved. In this paper, technics, microstructureand properties and crystal orientation of X80pipeline steel were comprehensively analyzedand the control factors influenced on arrest properties of pipeline steel was also studiedsystematically in our investigation.In this work, X80pipeline steel was taken as an object to be studied, systematicallystudied the relationship of between microstructures, orientations and process, also propertiesand crystal orientations. Gleeble1500D thermal simulation experiments were used to studystatic recrystallization softening rate and the influence of hot rolling process parameters onthe microstructure of X80steel. X-ray diffraction (XRD) was used to study thecharacteristics of the trend and the formation of the main hot-rolled texture componentsunder different process in pipeline steel. The electron backscatter diffraction technique wasused to collect information of the microscopic orientation of the fracture zone, Clarify therelationship between the textures and micro-orientation and mechanical properties of high-level pipeline steel. Based on this, research on factors influence the mechanical properties ofX80pipeline steel.The results indicated that reducing the final rolling temperature and increasingthe cooling rate can get more acicular ferrite, that is beneficial for DWTT performance; Inthe hot rolling process, the type of textures in X80pipeline steel evolve to {112}<110>and {111}<110>; Control the metallurgical quality and rolling process can improve thedistribution and size of the inclusions, so as to improve the tear resistance of pipeline steel;Raising {112}<110> and {110}<110> orientations and low-angle boundaries may causeDrop Weight Tear Test (DWTT) performance increased.