Design and fabrication of gradient cermet composite cutting tool, and its cutting performance

According to performance demands of tool materials for high speed machining difficult to cut materials, gradient cermet composite tool materials were designed and fabricated based on hot pressing sintering after dry pressing. The gradient cermet composite tool materials were composed of surface layer, subsurface layer and substrate and exhibited gradient microstructure and mechanical properties. The surface layer had a high hardness, subsurface layer had a high bonding strength and substrate had a high flexural strength. Three gradient composite cutting inserts were fabricated with the gradient structure on different tool faces. To evaluate the cutting performance of gradient cermet composite cutting inserts, effects of cutting speeds on the tool life and surface roughness were investigated during continuously dry turning 17-4 PH stainless steel. The developed gradient cermet composite cutting inserts showed longer tool life and better machining quality than conventional Ti(C,N) cermet inserts under the same cutting conditions. Cutting speeds played a significant effect on both tool life and failure mode of cutting inserts. The favorable cutting performance of gradient cermet composite cutting inserts was attributed to high surface hardness, good wear resistance of surface layer and reasonable gradient structure. (C) 2017 Elsevier B.V. All rights reserved.