  The effect of hydrogen on the fracture behaviour of austenitic stainless
steel has been investigated in the past [1][2]. It has been reported that
fracture initiates by void formation at inclusions and regions of enhanced
strain localisation [3]. There is experimental evidence that supports the fact
that hydrogen influences void nucleation, growth and coalescence during
material fracture [4]. This work investigates the effect of hydrogen on void
growth and coalescence in austenitic stainless steel. The effect of hydrogen on
void growth and coalescence for different stress triaxialities has been
examined by analysing the stress strain response of a single crystal
representative volume element (RVE). The results show that the higher the
stress triaxiality, the lower the equivalent stress required to yield. This
response is found to be similar irrespective of whether the material is being
exposed to hydrogen or not. Lower equivalent strain values to yield were
experienced for higher stress triaxialities for both hydrogen free and
hydrogenated samples. Hydrogen slowed down void growth at high stress
triaxialities but promoted void growth as lower triaxialities. For lower
triaxialities, the presence of hydrogen was found to initially inhibit void
growth at low equivalent strain values. However, this effect reversed at higher
equivalent strain values and hydrogen was found to promote void growth. The
effect of hydrogen promoting or inhibiting void growth have been shown to
increase in magnitude with increasing hydrogen concentration.
