Effect of vanadium microaddition on the microstructure and mechanical properties of casing pipes after normalizing process

Purpose: The aim of the paper is to determine the impact of vanadium microaddition on mechanical properties and microstructure of two steel grades with a different content of V, applied for production of casing pipes used in the extractive industry. Design/methodology/approach: Pilger process technology with subsequent normalizing was used. The tests were carried out on an industrial batch produced in the Rurexpol Department, and the research was done with the use of industrial research laboratories of Alchemia S.A. Group. The microstructure and mechanical properties were determined in the initial state and after normalizing at two temperatures: 940°C and 880°C. Static tensile test and Charpy V impact test have been applied. Findings: Mechanical properties, macrostructure and microstructure of steel pipes, obtained during production under industrial conditions, have been analyzed in the article. The effects of V content and hot-working and normalizing treatment affect substantially the mechanical properties and microstructure of the investigated steels. Research limitations/implications: It was found that the application of vanadium microaddition to the normalizing process after the hot-rolling has a beneficial effect on a strength-toughness balance only at a narrow range of technological parameters of the normalizing. Practical implications: The knowledge of the vanadium microaddition effect on the industrial production route is indicated in the paper. Originality/value: : The effect of vanadium microaddition has been proved to be very sensitive to the temperature conditions of the heat treatment.