The mechanical behavior of semi-solid MB15 magnesium alloy was investigated based on an isothermal compression experiment. The concept of thixotropic strength that is the maximum stress borne on the solid skeleton of semi-solid materials is put forward

which is the stress corresponding to the thixotropic point during steady deformation. Effects of some factors

including the heating temperature

strain rate

holding time

solid grain size

grain roundness as well as the intrinsic strength of the materials

on the thixotropic strength were analyzed

and existent conditions of the thixotropic strength was given. The results show that thixotropic strength is decreased with increase the heating temperature

decreasing the strain rate and extending the holding time while is increased with lowering the solid grain size

increasing the grain roundness and intrinsic strength of the material. The thixotropic strength exists when the solid grain in semi-solid materials jointed with each other to constitute the solid skeletons.