Evaluation of the Machinability of Cast Ti-Si Alloys with Varying Si Content

Abstract

This study evaluated the machinability of a series of binary Ti-Si alloys with a goal of developing a titanium alloy with better machinability than commercially pure titanium (c.p. Ti). The alloys were slotted using a milling machine and end mills under four cutting conditions. Machinability was evaluated through cutting force. The experimental results indicate that alloying with Si significantly improved the machinability of c.p. Ti in terms of cutting force under the present cutting conditions. As the Si content increases, the cutting force decreases then greatly increases. The cutting forces of c.p. Ti and the Ti-Si alloys increased as the feed rate increased from 30 to 60 m/min under the cutting speed of 55 or 110 m/min. The cutting force of Ti-5Si at cutting speed 55 m/min was approximately 49% lower than that of c.p. Ti; at cutting speed 110 m/min, it was approximately 62% lower than that of c.p. Ti. The cutting force of Ti-10Si was significantly higher than those of the other Ti-Si alloys and c.p. Ti, a result that can be explained by a higher degree of hardness (626 HV) and larger amounts of Ti 5 Si 3 (47.10 vol.%). For Ti-5Si, there was no obvious adhesion of chips observed on the cut surfaces. Furthermore, the specimens had the lowest surface roughness (Ra) values, approximately 0.3-0.4 lm, under the four cutting conditions. When cutting force, chip length, and surface roughness results are considered, the Ti-5Si alloy developed in this study is a viable candidate for machining.

Correlation between the microstructure and machinability in machining Al–(5–25) wt% Si alloys

“…Taking Ti−10Si specimen as an example, the high Ti 5 Si 3 content led to greater cutting forces than those of the unalloyed or low-Si specimens, the structures of which only contained hexagonal α -phase. 31 In this study, the cutting force components decrease with the increase in the Si content for hypereutectic alloys. On one hand, the radial component of cutting force decreases due to the decrease in Young’s modulus with the increase in primary Si particles.…”

“…Hsu et al 31 indicated that the chip length decreased with an increase in the concentration of Si, a result which can be explained by the reduced ductility as a result of alloying treatment. The chip manifests more brittle or fragile behaviors as the rising of hardness with increasing Si content, as well as the rising of cutting speed.…”

Increase in Efficiency of End Milling of Titanium Alloys Due to Tools with Multilayered Composite Nano-Structured Zr-ZrN-(Zr,Al)N and Zr-ZrN-(Zr,Cr,Al)N Coatings

“…The studies revealed that the values of the cutting forces were influenced more by the feed and less by the cutting speed. The influence of the silicon content in the titanium allow on its machinability was considered in [11]. It was found that the presence of silicon significantly increased the machinability of titanium alloys and thus led to a noticeable decrease in the cutting force.…”