Scientific journal
Scientific Review. Technical science
ISSN 2500-0799
ПИ №ФС77-57440

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INFLUENCE OF THE INTERCRITICAL HEATING TEMPERATURE ON THE FORMATION OF SUBGRAIN STRUCTURE IN LOW-ALLOY STEELS

Belikov S.V. 1 Sergeeva K.I. 1 Karabanalov M.S. 1 Popov A.A. 1 Al-Katawy A. Adwan 1, 2
1 Ural Federal University named after First President of Russia B.N. Yeltsin
2 Diyala University
The features of structure of low-alloy pipe steels such as 13CrV and 26Cr1MoV after quenching, intercritical quenching and high-temperature tempering are studied by electron-microscopic procedure. It is established that intercritical quenching of 13CrV from bottom of intercritical interval temperature Ас1-Ас3 provides the increased density of low angle boundaries in ferritic range, which is inherited in high-temperature condition. The heating temperature rise in two-phase region leads to abrupt shortening length of low angle boundaries. The steel structure after quenching on all modes contains together with ferrite as martensite and ferrite-carbide mixture. Secondary intercritical quenching of more alloy steel such as 26Cr1MoV from lowered temperatures of intercritical interval has resulted in formation of the extended grains of ferrite, which are collected in clusters, on a place of martensite lath. Carbides, which were extracted on ferritic crystal boundaries, restrain behavior of recrystallization processes. The heating temperature rise in intercritical region leads to partial dissolution of carbides, spheroidization of ferritic crystals and formation of significant amount small (2-3 µm) austenitic grains, which are provided essential breakage of products of double quenching.