Effect of microalloying and temperature at the end of hot rolling deformation on structure and properties of oil-and-gas line tubes made of 06x1 steel

Purpose. Establish effect of niobium microalloying and hot deformation conditions on structure and quality characteristics of oil-and-gas line tubes made of 06X1 steel. Methodology. Methods used: qualitative and quantitative metallography, chemical analysis, corrosion studies; mechanical property tests for tension and impact resistance. Findings. Effect of niobium microalloying of 06X1 steel hot worked at a tube rolling installation TRI ?140? on structure, mechanical and corrosion properties of oil-and-gas line tubes has been established. It was shown that completion of deformation within an intercritical temperature range causes decrease in impact resistance at temperatures from -40 and ? 60 ?С while high mechanical properties were retained in tensile tests. Heating of tubes to temperatures above Ас3 point (normalizing rolling) before their rolling at a sizing mill ensures a high complex of mechanical properties including impact resistance at subzero temperatures and high corrosion resistance properties of tubes. Originality. Microstructural features have been established and high mechanical and corrosion properties of oil-and-gas line tubes made of niobium microalloyed 06X1 steel have been scientifically substantiated. Practical value. The research results have been introduced at YuTiST Steel Tube Works (Nikopol, Ukraine) and can be used at other tube works in Ukraine.