  Seven-core Ag/Fe sheathed Sr0.6K0.4Fe2As2 (Sr-122) superconducting wires were
produced by the ex situ powder-in-tube (PIT) method. The relationship between
the cold-work deformation process and the superconducting properties of wires
were systematically studied. It was found that flat rolling can efficiently
increase the density of the superconducting core and largely improve the
transport critical current density (Jc) of as-drawn wires. The Jc of the best
sample achieved 21.1 kA/cm^2 at 4.2 K in self field, and showed very weak
magnetic field dependence in high fields. Our result suggested a promising
future of multifilamentary iron-based superconductors in practical application.
