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Е.Н. Каблов, Ю.А. Бондаренко, А.Б. Ечин
58
ISSN 0236-3941. Вестник МГТУ им. Н.Э. Баумана. Сер. Машиностроение. 2016. № 6
VARIABLE CONTROLED TEMPERATURE GRADIENT EFFECT
ON THE FEATURES OF STRUCTURE, PHASE COMPOSITION,
PROPERTIES OF HIGH-TEMPERATURE SUPERALLOYS IN THEIR
DIRECTIONAL SOLIDIFICATION
E.N. Kablov
Yu.A. Вondarenko
Viamlab1@mail.ruA.B. Echin
Federal State Unitary Enterprise All-Russian Scientific Research Institute
of Aviation Materials, Moscow, Russian Federation
Abstract
Keywords
The paper presents the research into the conditions of direc-
tional solidification with a variable controlled gradient. In
our work first, we determined the factors influencing the
tempe-rature gradient at the growth front . We found that
the most significant method is to remove the crystallization
heat by radiation or convection cooling when the mould is
immersed into the liquid metal coolant. When examining
this process, we discovered important factors: temperature
in the heating furnace, the liquid metal coolant temperature,
heat shields, separating the heating zone from the cooling
zone, the thermal conducti-vity of the ceramic mould. The
study offers the method for the experimental evaluation of
the temperature gradient values at the growth front by ther-
mocouples. Fin-dings of experimental studies conducted on
the single-crystal samples with crystallographic orientation
CLC <001> of Re-containing VZHM3 alloy, show that by
controlling the temperature gradient values (G = 20, 50, 100,
150 and 200
C / cm) we can significantly influence the size
of the structural superalloy components.
Metallurgical
studies carried out by optical and electron microscopy
showed that with the increase in the temperature gradient
with 20
C / cm to 200
C / cm, the interdendritic distance
halves from 310 microns to 130 mic-rons, the size of the
reinforcing particles
-phase in axes and mezhosnom space
is reduced by 3 times, the particle size of the eutectic
-
is
reduced by more than 2 times, the volume fraction of micro-
porosity is reduced by more than 10 times. By the method of
least squares we obtained the regularities of changes
of structural components VZHM3 alloy, which are present-
ed in the form of equations. With increasing temperature
gradient alloy, single crystal casting properties of cast sam-
ples VZHM3 values of tensile strength at 20
C increase in
~ 1.5 times, while 980
C — by 10–20 %, the time to failure
at 1100
C and
= 120 MPa increases more than 2 times.
This work is within the framework of an integrated research
area 9.5: Directional crystallization (with variable controlled
Directional solidification, temperature
gradient, a nickel single crystal super-
alloy, reinforcing
-
phase,
/
eutec-
tic, dendrite segregation, micro-poro-
sity, short-term strength, long-term
strength