Wear mechanisms and cutting performance of coated carbides in milling LPBF IN718 alloy under hybrid cryogenic conditions

Abstract

The present study investigates the milling of Inconel 718 (IN718) alloy fabricated using laser powder bed fusion (LPBF). Finish milling has been performed using Al-rich ternary-coated end mills under different lubri-coolant environments. An indigenously developed Cryo-MQL technology for greener manufacturing has been employed. Machinability results have been evaluated in terms of milling forces, tool wear progression, wear mechanisms, surface roughness, sub-surface damages and chip characteristics. MQL and Cryo-MQL conditions reduced milling forces by 50.6% and 47.2%, respectively. A 35–67% flank wear reduction has been obtained for the Cryo-MQL, resulting in minimal sub-surface deformation. Cryo-MQL caused the least milling-induced deformation with no transverse microcrack due to an excellent balance of cooling and lubrication actions. Micro-hardness of the machined sub-surface ranged 450–490 HV_0.03 (100–400 μm) for Cryo-MQL compared to 435–485 HV_0.03 in a deeper sub-surface deformation zone (250–450 μm) for dry milling. The synergy of lubri-coolant actions in Cryo-MQL mitigated frictional tracks, chip-side cracking and chip-edge fracture.

Keywords:

• Cryo-MQL
• Inconel 718
• laser powder bed fusion
• sustainable machining
• wear mechanisms

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Some part of the research was supported by PID2022-137380OB-I00 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe” by the “European Union”. Experimental tests were performed with support from the University Excellency groups granted by Basque Government IT 1573–22.