constant strain rate constant stress (creep)

Deformation tests ( constant T )

Constant strain rate testing

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Extensometer INSTRON 2630-014

(g.l. 10 mm, range 50 %)

At our lab:

Electromechanical (Instron 1123 or 5567)

Universal Electromechanical Testing Machine

Instron 5567 (dual column table top, 30 kN)

Temperature Chamber

Instron 3119(-70 °C / 250 °C )

ServohydraulicTesting Machines(MTS 810)

Constant strain rate behaviour

... details at T = 573 K (Th > 0.6 ! For the Al-alloy)

… why not constant loading-rate experiment?

Creep Testing: top-lever machine

PP

P

10 mm

initial state after creep

Compression Test

Compression Cage

Creep behaviour

The Monkman-Grant Relationship for time to fracture

)exp(1

RTQA

tcn

ssf

MGfss Ct * : time to fracture

: minimum creep rate

ft

ss

or, more general: MGfm

ss Bt * where: 0.77<m<0.93; 0.48<BMG<1.3

for Al, Cu, Ti, Fe and Ni base alloys (from Monkman-Grant research)

Test of Monkman-Grant for Cu

Engineering Estimates of Creep Behaviour

CtTLM r log

Larson-Miller parameter (LM)

ksi

ksi

Fig a