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Materials at High Temperatures (2006), 23(2)
Measurement
of flow stress in hot axisymmetric
compression tests
B.
Roebucka, J.D. Lorda,
M. Brooksa, M.S. Lovedaya,
C.M. Sellarsb and R.W. Evansc
aMaterials Centre, National
Physical Laboratory, Teddington,
bDepartment of Engineering
Materials,
cIRC for Computer Aided
Engineering,
ABSTRACT
This
paper describes good practice for the measurement of hot flow stress in
metallic materials. It
is applicable to hot (isothermal) uniaxial
axisymmetric compression tests at medium to high rates of
strain (10_4–102 s_1)
at deformation temperatures below the solidus.
Guidance
is provided on appropriate testpiece geometries and methods of verifying the
temperature
distribution along the length of the testpiece.
Flow diagrams are given showing all the steps that are
necessary, including the correction factors that
need to be applied for deformational heating and for
the determination of true stress. Details are given
of the calibration procedures that should be
followed to provide traceability to the National
Measurement System.
Technical
input to the document has been provided by a steering group containing academic
researchers and representatives of industrial
users and producers of a wide range of engineering
materials. An experimental and modelling
programme on an aluminium alloy, AA5052; on 316
stainless steel and a nickel alloy, Nimonic 901,
over a range of temperatures and strain rates has been
conducted during the preparation of the document
to underpin the procedures in the guide.
Keywords:
flow stress, hot axisymmetric compression tests
Measurement
of flow stress in hot plane strain
compression tests
M.S.
Lovedaya, G.J. Mahonb,
B. Roebucka, A.J. Laceyc,
E.J. Palmierec, C.M. Sellarsc and
M.R.
van der Windend
aMaterials Centre, National
Physical Laboratory, Teddington,
bInnoval (formerly at Alcan
International Ltd),
cDept of Engineering Materials,
dCorus Group,
ABSTRACT
This
Good Practice Guide is applicable to hot (isothermal) plane strain compression
(PSC) tests at
medium to high rates of strain (10_3 to
102 s_1)
at deformation temperatures below the solidus.
Guidance
is provided on appropriate testpiece geometries and methods of verifying the
temperature
distribution along the length of the testpiece.
Flow diagrams are given showing all the steps that are
necessary, including the correction factors that
need to be applied for breadth spreading of the
testpiece; machine origin and compliance,
friction effects and deformational heating. Details are given
of the calibration procedures that should be
followed to provide traceability to the National
Measurement System.
The
development of the procedure has been supported through experimental tests on
type 316
austenitic stainless steel at 1050 – 1150_C
and an aluminium alloy, AA5052, at 300_C
to 500_C at
strain rates ranging up to 100 s_1.
Technical
input to the document has been provided by a steering group comprising academic
researchers, representatives of industrial users
and producers of a wide range of engineering materials.
Keywords:
flow stress, hot plane strain compression test
Measurement
of flow stress at high temperature in
solid torsion tests
B.
Roebucka, M.S. Lovedaya,
Y. Chastelb, G. Fioruccib and
T. Dal Negroc
aMaterials Centre, National
Physical Laboratory,
bCEMEF, Sophia Antipolis,
cUniversity of
ABSTRACT
This
document outlines good measurement practice to be adopted for the determination
of flow
stress at high temperature in torsion tests on solid
metallic materials. The recommendations are
applicable to hot (isothermal) tests at medium to
high rates of strain (10_3–102 s_1)
at temperatures
relevant to metal working practice.
Guidance
is provided on appropriate testpiece geometries and methods of verifying the
temperature
distribution along the length of the testpiece.
Flow diagrams are given showing all the steps that are
necessary, including the correction factors that
need to be applied for deformational heating and for
the determination of true stress. Details are given
of the calibration procedures that should be
followed to provide traceability to the National
Measurement System.
Technical
input to the document has been provided by the steering group of a European SMT
funded project on High Temperature Testing, TESTIFY,
that contained representatives of industrial
users and producers of a wide range of engineering
materials as well as academic modellers.
An
experimental programme was conducted during the preparation of this document to
underpin
the procedures in this guide.
Keywords:
flow stress, high temperature, solid torsion tests