The Effect of Niobium and Vanadium on the Toughness of High Strength Alloyed Line Pipe Steel Used in Gas & Oil Pipeline

Abstract

The main objective of this research is to modify the alloy steels of high strength, toughness with good mechanical impact loading resistance properties, which are the general requirements of contractions high pressure, large diameters line pipe used for transporting oil and liquid gases, due to the large demine on these two product .The use of Niobium (low quantities) with very good controlling on all rolling stages of production plate, which are used in pipe manufacturing (longitudinal or spiral) by dabble submerge welding (outer and inner face) are the main technology used now in pipe manufacturing.The results of this work shows that the mechanical properties (strength, toughness, and impact resistance) are improved when we used Vanadium with Niobium (controlling quantities), because of their effects on grain size and initiations of precipitation Harding during phase transformations from austenite to ferrite and under full rolling parameters controlling. This leads to have high strength low alloyed line pipes steels (HSLALP) suitable for the longitudinal, spiral pipe mills which satisfy the user requirements in developing the most suitable chemical and mechanical properties line pipe steels.