Cutting performance and wear mechanism of TiB2-B4C ceramic cutting tools in high speed turning of Ti6Al4V alloy

TiB2-20vol%B4C (TB20) and TiB2-80vol%B4C (TB80) ceramic cutting tool materials were prepared by hot pressing, and then tested in turning of Ti6Al4V alloy with various cutting parameters. The tool life and wear mechanism of TB20 and TB80 were studied and compared with a commercial grade tungsten carbide tool (WO). The results of turning showed that effective cutting length of TB20 was about one third longer than that of TB80 and WO. Among the three tools, the increment of cutting temperature measured for TB20 was the lowest as flank wear increased from 0 to 600 mu m. Analysis showed that dominant wear mechanism was adhesive wear in all of the three tools tested, while chipping was also observed in TB80 and temperature deterioration in WO. In addition, the TB20 exhibited a much better integrity of cutting edge after flank wear reaching 600 pm, due to its higher toughness than TB80 and higher thermal resistance than WO, respectively. The adhesive layers of workpiece material on the rake and flank faces of both TB20 and TB80 were much thinner than that of WO, which suggested a lower adhesive wear rate in TiB2-B4C cutting tools. The high wear resistance of TiB2-B4C cutting tools is attributed to higher thermal resistance, higher hardness, and lower chemical affinity with titanium as compared with tungsten carbides, which makes them very promising materials for high speed machining of titanium alloys.