Effect of Severe Plastic Deformation on Magnetic and Mechanical Properties in Hard Fe–30% Cr–20% Co Magnetic Alloy

The effect of severe plastic deformation on the mechanical and magnetic properties is explored under conditions of equal channel angular pressing (ECAP). In addition, its impact on the structure of a Fe–30% Cr–20% Co hard magnetic alloy is estimated. Experiments are conducted using an alloy obtained using powder metallurgy. The ECAP phase develops between the quenching and heat treatment stages. Compared with the samples without severe plastic deformation, the samples undergoing ECAP feature significant changes in the magnetic hysteresis and mechanical properties. Triple extrusion through the die increases the yield strength almost twice reaching 2000 MPa. At the same time, ductility decreases by more than an order of magnitude making 1.1%. A single pass reduces the coercivity and leaves the residual induction practically the same. Triple extrusion reduces the magnetic hysteresis parameters by approximately fifty percent. For this case we register the following: residual induction Br = 0.38 T and coercive force Hc = 22.8 kA/m. Single pressing through reduces the coercive force, hardly changing the residual induction. ECAP involving three extrusions makes the grains non-equiaxial. In this case a coarse substructure is shown to develop inside relatively large elongated grains due to shear deformation generated along parallel planes. The shear lines exhibit an uneven pattern controlled by shear in the secondary system of parallel planes intersecting the initial planes. The samples without ECAP do not reveal this structure and the grains remain equiaxial.