Investigation On Microstructure And Mechanical Properties Of Armco Iron Processed By Equal-Channel Angular Pressing

Equal Channel angular pressing (ECAP) is an innovative technique that can producebulk ultrafine-grained (UFG) materials in product forms large enough for structuralapplications. In this work, we have studied, the influence of ECAP routes on themicrostructures and properties of BCC Armco iron. Microstructure evolution andmechanical performance were carried on the research analysis after ECAP. Simultaneouslywe have studied the different extrusion route influence on microstructure evolution andMechanical properties.Nowadays, ECAP technique is still a new research field in the world,and ECAP iron which less than 4 passes were studied most, however Imposing such highstrain(＞8) into the pure iron can improve ductility efficiently. So it Can be used to obtaingood mechanical properties in metals.Two ECAP routes, conventionally defined as A and Bc, were used to process the Febillets. Microstructures, micro-hardness, tensile properties were studied. The observationof microstructures indicates that the grain size of Armco iron refined while the ECAPpasses increased. After 4 passes by route B_C, the grain size reduced to 0.4μm, furtherpressing the grain-size can not be refined uniformly. We observed continues dynamicrecrystallization occurred at 8 passes by route B_C. Tensile tests revealed that the ultimatetensile strength (UTS) increased while the ECAP passes increased. After 6 ECAP passes byroute A and 8 ECAP passes by route B_C, the UTS rise to the peak. On the other hand, theductility lost seriously after the first pass; however it recovered slowly in the subsequentpressing. After 6 passes extrusion by route B_C exhibited both high tensile strength(σ_b=810MPa) and ductility (Elongationδ=15.1％) at room temperature.