Studying the plastic deformability of a Ni–Fe–Cr–Ti–B–C composite

Abstract

The paper studies changes in the structural state of a Ni–Fe–Cr–Ti–B–C composite after hot plastic deformation. The matrix of the composite consists of a mechanical mixture of two solid solutions: austenite and ferrite. Titanium carbide and diboride particles resulting from self-propagating high-temperature synthesis (SHS) are the strengthening phases. Additional strengthening is provided by carbide Cr23C6 and intermetallic Ni3Ti particles formed in austenite during cooling. The constituent with a ferrite matrix, which is a mixture of α-(Cr,Fe) + TiB2 + TiC + Cr23C6, is shown to have the highest ductility. The strongest constituent of the composite is represented by regions with an austenitic matrix and the most abundant TiB2 particles. These regions are characterized by the highest hardness, elastic modulus, elastic recovery Re and wear resistance ratio HIT/E. The hardness of the composite is 58 HRC. For plastic deformation of the composite, it is proposed to perform hot rolling at a heating temperature of 1000 °C under all-round compression. To do this, a composite specimen is pressed into a 10 mm steel shell, with 6 mm steel plates welded on top and from below. True plastic strain ε = 0.6 is achieved under these conditions. EBSD analysis testifies that the deformation is implemented due to dynamic polygonization and recrystallization of the austenitic and ferritic grains of the composite matrix. Dynamic recrystallization prevails in the austenitic grains, whereas dynamic polygonization predominates in the ferritic ones.