N. A. Tereshchenko

Structural aspect of delamination crack formation during the HTMT of steels with a ferritic structure

The fine structure, texture, and fracture of the ferritic 08Kh18T1 steel subjected to repeated hot rolling at temperatures of 800–1100°C and reductions of 35, 50, and 65% have been studied. When significant strains are reached, a layered subgrain structure forms in the steel, and {100} and {111} planes are predominantly located in the rolling plane. The mechanisms of delamination crack formation during rolling under HTMT conditions are considered. The development of a crack in a material with a layered structure is analyzed theoretically.

Structure formation in low-alloy pipe steel during heating in the intercritical temperature range

Effects of the temperatures of preliminary quenching and additional quenching from the intercritical range (ICR) on the impact toughness, hardness, and microstructure of a low-alloy pipe steel have been studied. A complex pattern of structural and phase transformations that occur during holding in the ICR of the initially quenched steel has been shown, namely, the development of the α-phase recrystallization and the formation of the γ phase in two ways—via the heredity mechanism and by an orientation-unrelated growth.

Specific features of low-temperature phase transformations in nitrogen-Containing Cr-Mn-based steels

Physical and mechanical properties of nitrogen-containing austenitic steels of different alloying systems have been studied at temperatures from −196 to 700°C in the quenched state. It has been found that nitrogen-containing Cr-Mn-based steels undergo a paramagnetic to antiferromagnetic ordering (with a manifestation of invar properties), the ΔE effect, and a resistivity anomaly. It has been shown that the behavior of the temperature dependence of the yield stress in nitrogen austenite is determined by several factors. Along with specific features of the dislocation structure determined by a low energy of stacking faults, the strengthening of nitrogen austenite is influenced by its magnetic state.

Influence of structure on static cracking resistance and fracture of welded joints of pipe steels of strength class K60

The static cracking resistance of a number of welded joints made from pipe steels of K60 strength class has been determined. It has been established that the deformation parameter CTOD varies significantly at identical parameters of weldability of steels. The character of fracture has been investigated and the zone of local brittleness of welded joints has been studied. It has been shown that the ability of a metal to resist cracking is determined by the austenite grain size and by the bainite morphology in the region of overheating in the heat-affected zone of a welded joint.

Effect of preliminary thermal treatment on decomposition kinetics of austenite in low-alloyed pipe steel in intercritical temperature interval

The decomposition kinetics of austenite that appears in the 13KhFA low-alloyed pipe steel upon heating the samples in an intercritical temperature interval (ICI) and exposure for 5 or 30 min has been studied by the method of high-speed dilatometry. The results of dilatometry are supplemented by the microstructure analysis. Thermokinetic diagrams of the decomposition of the γ phase are represented. The conclusion has been drawn that an increase in the duration of exposure in the intercritical interval leads to a significant increase in the stability of the γ phase.

Dilatometry investigation of austenite dissociation for low-alloyed pipe steel on cooling from intercritical temperature range

AbstractThe formation and post-decomposition kinetics of supercooled austenite of low-alloyed pipe steels obtained upon heating in an intercritical temperature range is investigated by velocity dilatometry. The decrease in the stability of austenite in the pearlite region after austenization in the intercritical temperature range in the grade-20FA steel in comparison with the stability of austenite obtained by heating to temperatures above

Effect of abrasive water jet on the structure of the surface layer of Al–Mg alloy

A_{C_3 }

Recrystallization of medium-carbon steel under nonequilibrium conditions of short-term heating to a temperature above Ac1

is found. It is shown that austenization in the intercritical temperature range affects the decomposition of supercooled austenite of the grade-13KhFA steel in a complicated manner, namely, the temperature of the onset of austenite decomposition decreases, and the temperature of the end of transformation increases.