  The c-axis textured Sr1-xKxFe2As2 tapes produced by cold rolling and
post-annealing, could carry a high super-current over 2*104 A/cm2. However, the
magnitude is far from its maximum, because of the current obstacles associated
with various defects in the material. To predict the maximal transport critical
current density, we modeled the current paths in a c-axis textured polycrystal
as a three-dimensional flow network, and calculated the maximum flow with the
Ford-Fulkerson algorithm. It indicates that a much higher super-current of
about 2*105 A/cm2 could be achieved in an ideal c-axis textured K-doped 122
polycrystal. The dependences of transport Jc on density, content of invalid
boundary and grain size and shape were also studied. The results imply that,
over 30% of the grain boundaries in the reported c-axis textured Sr1-xKxFe2As2
tapes may act as current obstacles, and the large ratio of width to thickness
was expected to be the most favorable grain shape for high transport Jc in
c-axis textured 122 superconducting tapes.
