Comparison of the chip formations during turning of Ti64 β and Ti64 α+β

Abstract

For a number of years, the rise in the number of titanium alloy grades and therefore of microstructures has hampered the productivity of titanium parts. In order to understand the phenomena involved, this study presents a comparison of the chip formations between two microstructures obtained from the same alloy. The first part presents the two alloys, their microstructures and their methods of production. The chip formation of each material is then presented and shows two completely different processes. The first process is classical, for which shear mechanisms appear to be cyclical. Conversely, the second process depends on the orientation of the microstructure when the shear occurs. For a better understanding of the phenomena, the effect of cutting speed and feed is also discussed. Finally, in the last section, chip formations for the two microstructures are summarized and perspectives are presented.

Machinability of cast titanium alloy Ti-6Al-4V with addition of boron

“…The actual deformation was found to depend on the orientation of the beta lamellae; however there was no influence on cutting forces when compared with two other microstructures; bi-modal and equiaxed. This influence of beta lamellae orientation was also found by Wagner et al when turning Ti-6Al-4V having two different microstructures, where it was stressed that new material behavior laws are needed to describe the material inhomogeneity [5].…”

Experimental and numerical investigations of the heating influence on the Ti5553 titanium alloy machinability

“…should be noticed that the temperature increases rapidly as explained by [24], however, the low thermal conductivity limits the effect on the microstructure and consequently in its evolution (Fig. 13b).…”

Kinematic fields measurement during Ti-6Al-4V chip formation using new high-speed imaging system

“…Understanding the mechanisms of chip formation under complex thermomechanical loads require developing dedicated experimental set-up. In the cutting zone, the material undergoes high plastic deformation and local temperature rise that may induce changes in the material microstructure [1,2] as well as its mechanical and physical properties. Establishing the link between the thermomechanical load and the material microstructure evolution leads to develop physical-based models [3][4][5][6] that are suitable for numerical simulation of the machining processes.…”