Equal Channel Angular Processing Of Pearlitic Steel

Severe plastic deformation (SPD) processing, especially Equal-Channel Angular Processing (ECAP) of steel and other iron-based alloys, has achieved increasing interest recently because of the potential for obtaining ultrafine grains and improving the properties.Equal Channel Angular Processing of the pearlitic steel (0.65 wt.%C) was successfully carried out at 650℃ with route C in this study, obtaining a total equivalent true strain ~5.The microstructure evolution of pearlitic steel in ECAP was investigated by means of transmission electron microscope and scanning electron microscope .The main results are as the following:1. The microstructure of lamellae pearlite has evolved ultrafine cementite particles throughout the ferrite matrix uniformly after five passes. The ferrite matrix is homogeneous grains, average grain size is -0.3 μ m.2. In ECAP route C, in order to accommodate the severe shear deformation the deformation form of lamellae cementite in pearlitic steel include periodical bending,periodical shearing and shearing fracture etc .3. On the present deformation condition, the cementite in pearlitic steel hasmore severe plastic deformation capability t-he max shear strain up to1.9.4. Excessive imperfections even sub-grained boundaries may be introduced in cementite .This makes the accelerating dissolution and spheroidization of cementite easy.5. The fracture and spheroidization of cementite shows obvious anisotropy.There are two possible mechanism about spheroidization ofcementite: the fracture cementite lamellae grows up non-uniformly and the fine spherical cementite particles grows up as the core.