Machining response of Ti64 alloy under Nanofluid Minimum Quantity Lubrication (NFMQL)

Rapid wear progression of cutting insert associated with attainment of excessive tool-tip temperature are indispensable causes which limit operational domain of cutting velocity during dry turning of Ti64 alloy. Again, to counteract demerits of flood cooling, jet of air-oil mist (MQL technology) is employed in which water-based coolants or vegetable oils are highly preferable. On the other hand, inclusion of nano-additives within base fluid, and supply the same through MQL system (NFMQL) is also a trendy area of research. Application potential of NFMQL is understood over conventional MQL in terms of better cooling, and lubrication effects due to improved thermo-physical, and tribological properties of the resultant cutting fluid. In this context, present study aims to assess performance of MQL jet containing biodegradable Jatropha oil (carried by pressurized air) when applied during longitudinal turning of Ti64 work alloy. In addition, advantages of 2D layered-structured graphene nanoplatelets (when dispersed into Jatropha oil), in purview of machining performance on difficult-to-cut Ti64 alloy under NFMQL, are studied in this work. Experimental data are compared on the basis of different lubrication conditions (dry, conventional MQL, and NFMQL). Morphology of tool wear is studied in detail. The work extends towards studying chip morphology and machined surface finish of the end product, as influenced by variation in lubrication conditions.

An innovative method to assess and manage residual stresses in additively manufactured titanium

A simple method for residual stresses (RS) evaluation in additively manufactured titanium samples is described in this study. This method allows to obtain samples that are separated from the build plate but still include building’s RS. Thanks to these samples, the influence of time and temperature on thermal stress relieving performance and microstructural evolution for Ti64 alloy processed by LBM have been analysed. Additionally, the obtained data allowed to compare the thermal stress relief behaviour of additively manufactured parts to conventional wrought alloy. Process simulations have also been undertaken to predict RS fields and check this method accuracy.

The Effects of Laser-Assisted Ultrasonic Nanocrystal Surface Modification on 3D-Printed Ti-6Al-4V Alloy

In this paper, 3D-printed Ti-6Al-4V (Ti64) alloy, a hard-to-deform alloy with poor surface finish and high porosity was processed by an innovative technique, laser-assisted ultrasonic nanocrystal surface modification (LA-UNSM). The localized thermal effect of continuous laser decreases the flow stress of the alloy effectively. The effects of LA-UNSM on surface finish, microstructure, and surface hardness were investigated and compared with traditional UNSM treated samples. It is found that much smoother and harder surface was obtained after LA-UNSM. In addition, LA-UNSM also led to a thicker plastically-affected layer compared with UNSM process only. It is found that the LA-UNSM is a very efficient post-processing technique for 3D-printed alloys since it makes the thermal and mechanical effects work synergistically and energy-efficiently.