The effects of cryogenic cooling on tool wear and chip morphology in turning of tantalum-tungsten alloys Ta-2.5W

• Published in: Journal of manufacturing processes Vol. 86; pp. 152 - 162
• Main Authors: Wang, Ruibin, Wang, Xibin, Yan, Pei, Zhou, Tianfeng, Jiao, Li, Teng, Longlong, Zhao, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 27.01.2023
• Subjects: Chips evolution; Cryogenic cooling; Rehbinder effect; Tantalum‑tungsten alloys; Tool wear; Rehbinder effect; Tantalum‑tungsten alloys; Chips evolution; Cryogenic cooling; Tool wear
• ISSN: 1526-6125; 2212-4616
• DOI: 10.1016/j.jmapro.2022.12.063

Tantalum‑tungsten alloy is particularly difficult to cut due to its high plasticity. Environmentally friendly liquid nitrogen cooling and hybrid minimum quantity of lubricant-low temperature CO2 (MQL + CO2) technology can improve the machinability of ductile materials. In this paper, the experimental and numerical turning of tantalum‑tungsten alloy Ta-2.5W were carried out under cryogenic cooling conditions. The effects of liquid nitrogen cooling and MQL + CO2 cooling on the wear mechanism of cutting tools and the formation mechanism of chips were studied. The Rehbinder effect induced by the surfactant in MQL + CO2 system was analyzed. The results show that the cutting tool life can be effectively improved by 50 % in turning of Ta-2.5W under both cryogenic cooling conditions. Different from the flank wear dominated by adhesive wear under water-based emulsified cutting fluid, the tool failure was mainly caused by the notch wear under cryogenic cooling conditions. The chips in turning of high plastic Ta-2.5W showed a “pomelo-meat shaped” morphology with non-uniformed and non-periodic folds. Rehbinder effect was induced by the surfactant in MQL + CO2 system, which transformed the “pomelo-meat shaped” chips into “layered-rock shaped” chips. Under this effect, the machinability of tantalum‑tungsten alloy was effectively improved with a reduction of chip thickness and increment of the tool life. •The effects of cryogenic cooling on the machinability of Ta-2.5W was studied.•The turning experiments under liquid nitrogen and MQL + CO2 cooling were carried out.•Rehbinder effect induced by surfactants in MQL + CO2 system was found and discussed.•The influence of surfactants in the morphology evolution of chips was analyzed.