Numerous experimental studies on changes of the porosity and density of
various metals and alloys due to the formation and development of micropores
and microcracks in the process of high-temperature creep are carried out. The
results of these studies allow us to consider the density as an integral measure
of the structural micro-defects accumulation, and the damage parameter is
dened as the ratio of current density to initial density. Taking into account
this parameter and the mass conservation law interconnected kinetic equations
for creep deformation and damage parameter are formulated. In the case of
pure brittle fracture the analytical solutions of these equations are received and
the criterion of long-term strength is formulated. The ductile-brittle fracture
is also considered. An analytical solution connecting the damage parameter
to the value of deformation is obtained. In this case, the creep deformation
is calculated approximately. The appropriate choice of the coecients of the
approximate solution allows describing the experimental creep curves.