Through electrolytic deposition ZrO2, cold work, and
recrystallization annealing, the effects of oxide films and
microstructures on the hydrogen diffusion of the AISI 430
stainless steel had been investigated. The time-lag (),
breakthrough time (), diffusivity and sublayer concentration
were derived by hydrogen diffusion tests. The morphology and
microstructures were analyzed by scanning electron microscopy
(SEM), optical microscopy (OM), and X-ray diffractometer (XRD),
respectively.It was found that thickness of ZrO2 coating on 430
stainless steel is increased with increasing time, while the
time-lag was not. Because of the longer deposition time, the
micro-crack would be found during drying or sintering, which
made hydrogen atoms easier diffuse into the 430 stainless steel
substrate. Only for a proper coating time, a uniform ZrO2 film
could be obtained. Its effect of preventing the hydrogen
diffusion was even better than thermally grown oxide films on
430 stainless steel. By the analysis of a mathematical model,
the retarding effect on hydrogen entry of electrolytic
deposition ZrO2 on AISI 430 stainless steel is mainly because of
a very low diffusivity .The dislocation density was increased
with the increasing of cold work degree, so was the dislocations
trapping effect which would decrease the effective diffusivity,
especially in 50% cold work. After annealed at 1073K, the
grain size of 50% cold work 430 stainless steel was increased,
and the ratio of grain boundary to lattice was decreased with
increasing time. XRD showed the highest ratio of (110) preferred
orientation and the hydrogen permeation tests showed the
shortest time-lag for 120 min annealing. It was considered that
a quicker diffusion path such as the lattice diffusion of (110)
preferred orientation replaced that of random orientation, and
the grain boundary as a barrier for lattice diffusion was
further reduced.