As oil and natural gas resources are often located in remote areas and harsh environments, greater pressure pipelines transporting, complex and corrosive media, and pipeline welding assembly ring general in the wild, which not only requires pipeline steel with high strength, and requirements should be good toughness, fatigue resistance, fracture resistance and corrosion resistance, but also requires improving the mechanical properties should not deteriorate welding and processing properties of the steel.
In order to improve transport efficiency, large oil and gas fields of transport and pipeline design is concerned, tends to increase the working pressure and delivery diameter, therefore, on the strength of pipeline increasingly demanding. Pipeline strength including tensile strength and yield strength. Intensity with different material composition variation is large, and the processing state is different, the intensity change is great. In general, the yield strength of steel to increase its plasticity, such as Charpy impact energy will be reduced, which gives transport medium and high voltage requirements, such as good toughness properties of high strength steel production has brought conflict, therefore, spurred by solid solution strengthening, grain grain refinement and other means to make the pipeline to achieve enhanced performance requirements.
Toughness is one of the important properties of pipeline, which includes the impact toughness, fracture toughness. Restricted due to improved toughness strength, and therefore the production pipeline is often used grain refinement can improve the strength of this unique and can improve the toughness of toughening means, in addition, inclusion of the pipeline toughness has serious dangers Therefore, to reduce the content of harmful elements in steel and inclusion modification is an effective means to improve the toughness.
Steel welding material of the welding process is the adaptability that, under certain conditions to obtain the degree of difficulty of the welding quality of the welded joint. It includes binding properties (that is, when the welding process of welding a metal to form a complete joint capacity) and performance (already welded joint welded into the safe operation capacity under conditions of use). Welding of high strength steel to improve measures is multifaceted, first of all, the chemical composition of the steel has a direct and significant impact on the high-strength steel welding, soldering and effective measures to improve performance is to reduce the content and selection of appropriate alloying elements.