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, and 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 this two product. The use of Niobium (low quantities) with excellent control on all rolling stages of production plate, which are used in pipe manufacturing (longitudinal or spiral) by dabbling submerge welding (outer and inner face) is the primary technology used now in pipe manufacturing. The results of this work show 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 high-strength low alloyed line pipe steels (HSLALP) suitable for the longitudinal, spiral pipe mills, which satisfy the user requirements in developing the most suitable chemical and mechanical properties of line pipe steels.

Keywords

• alloy steels
• Niobium
• Vanadium
• pipe steels