  In the paper we predict a distinctive change of magnetic properties and
considerable increase of the Curie temperature caused by the strain fields of
grain boundaries in ferromagnetic films. It is shown that a sheet of
spontaneous magnetization may arise along a grain boundary at temperatures
greater than the bulk Curie temperature. The temperature dependence and space
distribution of magnetization in a ferromagnetic film with grain boundaries are
calculated. We found that $45^\circ$ grain boundaries can produce long-range
strain fields that results in the width of the magnetic sheet along the
boundary of the order of $ 0.5 \div 1 \mu m$ at temperatures grater than the
bulk Curie temperature by about $10^2$ K.
