Azerbaijan Technology University, Baku, Azerbaijan

A. T. Mammadov, Dr. Eng., Prof., Professor–adviser, Dept. of Metallurgy and Technology of Materials, e-mail: ariff-1947@mail.ru
A. A. Jafarova, Cand. Eng., Associate Prof., Dept. of Chemical Technology, Processing and Ecology, e-mail: afetceferova8@gmail.com
S. M. Rustamova, Senior Lecturer, Dept. of Chemical Technology, Processing and Ecology, e-mail: sevilrustemova70@mail.ru

The article presents the results of development of the technology of thermal strengthening of coupling blanks made of carbon and low-alloy steels 32G2, intended for oil production. At the same time, the problem of obtaining coupling blanks with a strength of at least strength group L was solved. It was found that according to the existing technology of “Azerboru”, hardening of hot-rolled couplings made of steel 36G2S is carried out in a continuous sectional furnace, with cooling from the outer surface in a sprayer. However, the existing technology, even when using alloy steel, does not ensure a homogeneous structure and uniform properties of the metal along the wall and length of the coupling pipes. In this regard, the paper proposes a new technology for thermal hardening of coupling blanks using equipment from EMAG (Germany), which provides for induction heating of blanks for hardening and their accelerated cooling during tempering. To test the technology for manufacturing coupling blanks on EMAG equipment, carbon steels 20 and 40, as well as low-alloy steel 32G2, were used as materials. Coupling blanks made of steel 20 after hardening and tempering on EMAG equipment showed low mechanical properties and an uneven structure across the thickness of the pipe wall. Steel 40 after hardening and tempering provided sufficiently high strength and corresponded to strength group M. As a result of the conducted research, a technology for thermal strengthening of coupling blanks of various sizes was developed and mastered, which includes induction heating of blanks, cooling in water and tempering.
The work was carried out with the financial support of the Science Foundation of Azerbaijan - Grant No. AEF-MCG-2023-1(43)-13/01-M-01.

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