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The paper presents the results of experimental investigations concerning the kinetics of static
precipitation in HSLA steels with microadditions of Nb, V, Ti and N in the course of isothermal
holding between the successive cycle of plastic hot deformation. The process of deformation was
realized making use of a torsional plastometer and Gleeble’s thermomechanic simulator. Particularly,
the kinetics of static precipitation in unstrained austenite of steel B2 (0,16%C, 0,030%Nb, 0,01%V,
0,0060%N) was tested applying the method of hot torsion, and the precipitation in steel G1 (0,16%C,
0,037%Nb, 0,002%V, 0,004%Ti, 0,0098%N)both its unstrained state and after the deformation of
austenite at elevated temperature by means of the method of axial-symmetric compression of the
samples. The curves of the kinetics of precipitation in the austenite were determined basing on
measurements of changes of the value ε m [1,2], corresponding to σ max on the flow curves obtained in
the course of continuous deformation, carried out after a varying duration of isothermal holding (from
1 to 10800 seconds). The kinetics of static precipitation concerning steel B2 were tested at a tempera-
ture of 900°C after its austenization at 1150°C, whereas in the case of steel G1 this was accomplished
at a temperature of 1100°C after its austenization at 1200°C. The process of precipitation of this kind
of steel was tested also after its initial deformation (ε = 0,2) at a strain rate of 1,0s -1
, the conditions of
temperature remaining unchanged.
The precipitation in the matrix of stable austenite of steel G1 was also investigated using a electron
transmission microscope on samples quenched immediately after their hot deformation and at a
varying duration of isothermal holding. The effects of precipitation in the phase γ, taken over from
martensite, were analyzed mainly by means of electron diffraction and verified by observations in the
dark field, aided by X-ray microanalysis.
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