Azerbaijan Technical University (Baku, Azerbaijan)

A. T. Mammadov, Dr. Eng., Prof., Advisor of the Dept. “Metallurgy and Materials Technology”, ariff-1947@mail.ru
S. N. Namazov, Dr. Eng., Prof., Dept. “Metallurgy and Materials Technology”, subhan.namazov@aztu.edu.az
M. Ch. Huseynov, Cand. Eng., Associate Prof., Dept. “Metallurgy and Materials Technology”, muxtar.53@mail.ru
A. A. Jafarova, Cand. Eng., Associate Prof., Dept. “Chemical Technology, Processing and Ecology”, afetceferova8@gmail.com
S. M. Rustamova, Cand. Eng., Senior Lecturer, Dept. “Chemical Technology, Processing and Ecology”, sevilrustemova70@mail.ru
G. A. Mirzayeva, Cand. Eng., Senior Lecturer, Dept. “Chemical Technology, Processing and Ecology”, gulnaz.mirzayeva@aztu.edu.az

This article investigates defects arising during the production of 32G2 steel used for manufacturing pipe blanks intended for oilfield tubing. A comprehensive analysis of two pipe&blank fragments was conducted, including examination of their external appearance, determination of chemical composition, as well as macroanalysis, fractographic study, and metallographic investigation of the metal structure. Particular attention is given to evaluating liquation heterogeneity and the level of contamination by non-metallic inclusions. It was established that the chemical composition of all examined samples fully complies with the requirements for 32G2 steel. Macrostructural analysis revealed that the primary defect of these blanks is pronounced liquation heterogeneity accompanied by the formation of impurity-concentration zones. Fractographic studies identified the presence of pores and cracks within the liquation areas. The fracture surfaces are characterized by transcrystalline brittle cleavage. Metallographic analysis confirmed the presence of regions enriched with low-melting elements–primarily phosphorus and sulfur–indicating non-uniform metal solidification conditions. The investigation of non-metallic inclusions was conducted using optical and electron microscopy, as well as energy-dispersive microanalysis. It was determined that all blanks contain pores (voids) in the central (axial) zone. Metal contamination by non-metallic inclusions was assessed according to scale Sh6. The contents of sulfides and oxides do not exceed 1 point, whereas undeformed silicates reach up to 5 points. Based on the obtained results, it is proposed to improve the current steel-melting technology by placing greater emphasis on the stages of deoxidation and desulfurization. Adjusting these processes will reduce liquation heterogeneity and decrease the amount of non-metallic inclusions, ultimately improving the quality of pipe blanks. 

This work was supported by the Azerbaijan Science Foundation Grant № AEF – MGC – 2024 - 2(50) –16/01/1 – M – 01.

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