Plane strain compression is a versatile laboratory testing method for
simulating industrial hot working operations such as plate and strip r
olling. The deformation can be closely controlled to the required cond
itions of temperature and strain rate, and high strains can be achieve
d without instability. However, for accurate determination of flow str
ess, care must be taken with experimental procedure and the interpreta
tion of the measured force-displacement data. This paper reports the r
esults of work carried out in three laboratories on samples of the sam
e cast of Al-1% Mn alloy. In particular, the effects of spread and fri
ction are analyzed as a function of initial specimen geometry. When co
nsistent procedures are used it is shown that excellent reproducibilit
y of flow stress data is obtained between laboratories. In deriving co
nstitutive relationships, the importance of considering the effects of
lubricant films, of deformational heating, and of heat transfer are c
learly demonstrated.