Fabrication and cutting performance of reactively hot-pressed TiB2-TiC-SiC ternary cutting tool in hard turning of AISI H13 steel

Abstract

TiB2-based ceramics are promising materials for fabrication of cutting tools, which are used in hard machining of difficult-to-cut materials. A TiB2-TiC-SiC ceramic cutting tool composite was fabricated via the reactive hot pressing (RHP) process. The microstructure and mechanical properties, as well as the strengthening and toughening mechanisms, were investigated. Elongated TiB2 grains with a diameter of 0.5–1 μm and an aspect ratio of 3–8 were in situ synthesized and uniformly distributed in the composite. The mechanical properties were tested, and the flexural strength was 768 MPa, the fracture toughness was 7.3 MPa m1/2, and the Vickers hardness was 21.8 GPa. The good mechanical properties were ascribed to the clean interface and toughening effect of the elongated TiB2 grains. The cutting performance including tool life and surface roughness, as well as tool failure mechanisms in hard turning of 55 HRC AISI H13 steel, was investigated. The effects of cutting parameters on tool life and surface roughness were studied. For the investigated range of cutting parameters, the optimal cutting speed, feed rate, and depth of cut were 100 m/min, 0.1 mm/rev, and 0.25 mm, respectively. Under this condition, the tool life and surface roughness were 45.4 min and 1.289 μm, respectively. The failure of the fabricated cutting tool was characterized by nose and flank face wear. The wear mechanisms consisted of adhesive wear, oxidation wear, and diffusion wear.