Due to manufacturing characteristic

the strength and life of powder metallurgy alloy are sensitive to micro defects

such as nonmetallic inclusion

pores

and nicks on the surface.A distinct character of failure of this kind of material is scatter

which makes life prediction more difficult.In this paper

based on the defect populations of domestic PM alloy and some probability failure methods established in reference

definition of the probability for the presence of a defect inside the surface

sub-surface and internal region is given first

and then a probabilistic model is set up

which can calculate the failure probability caused by defects having different shapes and different sizes

being in different regions

and also can calculate the total failure probability.It is concluded that the method can describe the effect of probabilistic character of defects on the strength and life of PM alloy

and it is proved to be valid.