*Department of Mechanical and Intellectual Systems Engineering, Toyama ... creep-fatigue conditions. The fracture mode of the alloy with equiaxed ÆÑ and the.
Materials
Science Research
General
International,
Vol.4,
No.3
pp. 206-211
(1998)
paper
EFFECT
OF
MICROSTRUCTURE
CREEP-FATIGUE
ON
BEHAVIOR
AT
ELEVATED
IN
CREEP
AND
Ti-6Al-4V
ALLOY
TEMPERATURE
Seiichi NISHINO*, Kazuaki SHIOZAWA* and Yasunori AIKAWA** *Departmentof Mechanicaland Intellectual SystemsEngineering, ToyamaUniversity, Gofuku,Toyama930-8555,Japan **GraduateSchool of Engineering, ToyamaUniversity,Gofuku,Toyama930-8555,Japan Abstract:
The
alloy
having
treatment and
of
and
10min
alloy
with
at
out
773K
failure
under
strain
air.
Creep
and
effect
transgranular
under and
was of
The
at
than
the
alloy
fracture
mode
alloy
that
of
the
other
the ƒ¿
load
alloy
hand,
the
at
as
crack
of the at
than
alloy
the
the
with
grain
Creep-fatigue of that
number of
2min of
of
the
crack
the
cycles
other
two
initiation
bimodal
life
structures
lenticular ƒ¿
boundary
heat
equiaxed ƒ¿
to
that
with
Ti-6Al-4V
times
similar The
lower
and
air. hold
was
compared
equiaxed ƒ¿
the
different of
in
with
structure.
was
small
precipitated
773K
structure bimodal
in using
waveform
structure
with
studied
(composed
conditions
with
was
alloy
was
bimodal
equiaxed ƒ¿
life
layer
and
a trapezoidal
with the
773K
prepared
structure
lenticular ƒ¿
the
at
microstructures
constant
the
of
between
of
using
propagation
On
interface
under
with
crack
condition. the
of
higher
on
creep-fatigue
propagated
out conditions
strength
behavior
types lenticular ƒ¿
carried
controlled
condition
creep-fatigue
three
structure,
were
of microstructure conditions.
and The
rupture
structure
creep-fatigue
initiated
tests
total
creep-fatigue
The
under
Creep
in
creep
equiaxed ƒ¿
under
lenticular ƒ¿
structures.
the
structure.
carried
on
microstructures.
included
lenticular ƒ¿) were
microstructure
different
conditions
tests
to
effect
three
was
structure
and
the
was
lenticular ƒ¿
structure.
Key words: Creep, Low-cycle fatigue, High temperature, Heat treatments, Ti-6Al-4V alloy, Strain hold, Microstructure
1.
kinds
INTRODUCTION
of
microstructures
prepared Increased
uses
engines,
titanium
airframes
recently
and
attracted
nents
are
usually power
important
work
as
creep
using
upon
changes to
clarify
strength
and
alloys
alloys
the
on
creep
the
cyclic
low-cycle elevated
of
the
titanium
out
under
for
of
the
1Omin
depend
2.
important
strength
been
reported
(equiaxed ƒ¿
fatigue
life
processed This
elevated
titanium
is
due
the ƒ¿+ƒÀ In
at
to
between titanium
titanium
Ti-6Al-4V
Received
at 773K
alloy
of
material
(lenticular ƒ¿
alloy
August
to and
creep
was
25,
establish
the
elevated
on
of
initiation
the
and
investigated
properties the
creep-fatigue in
this
in
The
6.29Al,
hold-times
air
of
structures
in
Fig.
4.13V,
using of 2min
average
three
1997
206
air
a and
hereafter
grain
structure
equiaxed ƒ¿ size
as
E),
to heat
structure of
by
8.7ƒÊm.
(1123K
as
E+L).
has ƒ¿-phase The
Ti.
the
lenticular ƒ¿
Three
different for
lenticular ƒ¿
treatments
weight
0.0077N, of
hereafter referred for 2h, air cooled,
these
alloy,
in
balance
obtained
referred by
a titanium
0.166O,
and
to
cooled, (1223K
obtained
was
composition
were
referred
for 1h, structure
The
study
0.194Fe,
equiaxed ƒ¿
hereafter
cooled,
1.
this chemical
