Ductile and brittle transition behavior of titanium alloys in ultra-precision machining

Abstract

Titanium alloys are extensively applied in biomedical industries due to their excellent material properties. However, they are recognized as difficult to cut materials due to their low thermal conductivity, which induces a complexity to their deformation mechanisms and restricts precise productions. This paper presents a new observation about the removal regime of titanium alloys. The experimental results, including the chip formation, thrust force signal and surface profile, showed that there was a critical cutting distance to achieve better surface integrity of machined surface. The machined areas with better surface roughness were located before the clear transition point, defining as the ductile to brittle transition. The machined area at the brittle region displayed the fracture deformation which showed cracks on the surface edge. The relationship between depth of cut and the ductile to brittle transaction behavior of titanium alloys in ultra-precision machining(UPM) was also revealed in this study, it showed that the ductile to brittle transaction behavior of titanium alloys occurred mainly at relatively small depth of cut. The study firstly defines the ductile to brittle transition behavior of titanium alloys in UPM, contributing the information of ductile machining as an optimal machining condition for precise productions of titanium alloys.

Influence of Feed Rate Response (FRR) on Chip Formation in Micro and Macro Machining of Al Alloy

“…The chip morphology changes to discontinuous, transition (quasi-continuous), and continuous, with an increase in the feed rate similar to the response of cutting speed [57], the feed rate response can be utilized to develop the phenomenology in chip formation. The onset of voids and crevices on the chip surface is triggered by the intense plastic deformation, as the tool-chip contact/interaction becomes unstable with the reduction of UCT (h c ) [73]. A similar phenomenon of Ti chip surface tearing occurred, as a result of the inability of the stable formation of long and continuous chips due to the inducement of highly compressive stress at extremely small UCT(h c ) [74].…”

Effect of parameters on surface roughness during the ultra-precision polishing of titanium alloy

“…Bai [ 13 ] investigated the influence of the ultra-precision cutting on the mechanical properties and microstructure of titanium alloys. Yip [ 14 ] surveyed the brittle and ductile transition phenomenon of titanium alloys during the ultra-precision turning process with a single point diamond tool. Xiong [ 15 ] combined simulations and experiments to analyze the cutting mechanism of titanium alloys during ultra-precision cutting.…”

“…An increasing amount of attention has been paid to the ultra-precision cutting of various titanium alloys [9][10][11][12][13][14][15][16][17]. When using the diamond tool in ultra-precision turning, Colafemina [9] analyzed the surface quality of Ti6Al4V alloy and Ti.…”

Study on Influence of Ultrasonic Vibration on the Ultra-Precision Turning of Ti6Al4V Alloy Based on Simulation and Experiment

“…Hu and Zhou [13] adopted the experimental method to investigate the wear mechanisms of diamond tool in ultra-precision cutting of Ti6Al4V alloy. Yip [14] used the ultra-precision machine to cut Ti6Al4V alloy and investigated the brittle and ductile transition phenomenon of material. We have also done some research to explore the cutting mechanism of titanium alloys during ultraprecision turning [17]- [19].…”