Abstract: The Bauschinger effect and
back stress in Mn-V heat treated dual phase steel have been
investigated. The influence of reverse flow and aging at 175℃ on
the Bauschinger effect and back stress, and relationship between
back stress and microstructural parameters have been measured.
The results show that there are Bauschinger effect and permanent
softening in the dual phase steel studied. The Bauschinger
effect is mainly related to mobile dislocations and dislocation
configurations with directionality in their resistance to motion
and the back stress in the matrix due to prestrain. Only when
the dislocations are mobile, the back stress can facilitate
dislocations to reverse motion resulting in the decrease of
yield stress during the reverse flow and rounding off of reverse
fow curve as well as producing Bauschinger effect. The
relationship between the back stress and microstructural
parameters of dual phase steel were calculated by using the back
stress hardening model evolved by Brown and Stobbs for
describing back stress hardening mechanism. The calculated
results have good corelation with measured results. It shows
that the back stress hardening mechanism in dual phase steel
bears analogy with that in dispersion hardened alloys. The aging
at 175℃ can dispel Baauschinger effect but does not change the
value of back stress in dual phase steel. However, the reverse
flow can simultanuously decrease or dispel Bauschinger effect
and back stress in dual phase steel.
Key words:
Dual phase steel Bauschinger effect Back stress Aging Microstructural parameter
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