Electrometallurgy Today, 2021, №03



2021 №03 (05)

DOI of Article 10.37434/sem2021.03.06

2021 №03 (07)

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Electrometallurgy Today (Sovremennaya Elektrometallurgiya), 2021, #3, 35-41 pages

Structure and fracture mode of haz metal of corrosion-resistant 06G2BDP steel

O.M. Berdnikova, V.D. Poznyakov, V.A. Kostin, T.O. Alekseenko, S.L. Zhdanov, E.V. Polovetskyi

E.O. Paton Electric Welding Institute of the NAS of Ukraine. 11 Kazymyr Malevych Str., Kyiv, 03150, Ukraine. E-mail: office@paton.kiev.ua

Abstract
ВThe regularities of the influence of thermal cycles of welding on structural-phase transformations in the HAZ metal of 06G2BDP steel, on parameters of the structure forming in the metal at different cooling rates (w6/5 from 1 to 64 °с/s), and on its mechanical properties and fracture mode at static and dynamic loading were studied. Structural-phase transformations were investigated on model samples-simulators in Gleeble 3800 complex. The methods of light and scanning electron microscopy were used to determine the structural parameters, namely grain size, microhardness, as well as the features of the fracture mode. It is shown that base metal of 06G2BDP steel has a fine-grained ferrite-carbide structure; after impact bend testing the sample fracture demonstrates a ductile mode that ensures not only its high level of mechanical properties, but also the required crack resistance. Depending on the metal cooling rate, in the HAZ overheated zone its structure can change from ferritic-pearlitic (at w6/5 = 1 °с/s) to bainitic (at w6/5 = 20 °с/s) and bainitic-martensitic one (at w6/5 ≥ 20 °с/s). With increase of the cooling rate, the quantity of lower bainite in the metal becomes greater and refinement of the packet and lath substructures takes place, leading to increase of microhardness level and, consequently, to higher strength characteristics of HAZ metal of 06G2BDP steel at preservation of its ductility properties. Ref. 19, Tabl. 1, Fig. 6.
Keywords: high-strength corrosion-resistant steel; simulation of welding thermal cycles; cooling rate; heat-affected zone; microstructure; mechanical properties; fracture mode

Received 20.05.2021

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