Inconel 718 süperalaşımının delinmesinde kriyojenik soğutmanın delme performansı üzerine etkilerinin araştırılması

Abstract

Highlights:Graphical/Tabular Abstract  Drilling of Inconel 718 superalloy under cryogenic conditions with solid carbide drills  Temperature measurement depending on cutting depth  Improvement of surface integrity with cryogenic conditions Drilling of Inconel 718 which is a nickel-based superalloy is a challenging process because its superior physical and mechanical properties lead to the high thermal and mechanical loads on a twist drill. In order to obtain desired hole quality, excessive heat and forces generated during drilling must be minimized using suitable coolants and/or lubricants. Figure A. Cutting conditions, thermocouple connection setup, and the obtained cutting temperature, torque and thrust force results.Purpose: This study aims to investigate experimentally the effects of cryogenic cooling on cutting performance in drilling of Inconel 718.Theory and Methods: Drilling tests were performed at a constant cutting speed (10 m/min) and a feed (0.02 mm/rev) using uncoated and TiAlN coated solid carbide twist drills under cryogenic, wet and dry conditions. The effects of cooling/lubrication conditions and coating material were examined in terms of thrust force, torque, cutting temperature, burr formation, chip formation, subsurface deformed layer thickness, microhardness change and average surface roughness. Results:Cryogenic cooling significantly decreased the cutting temperatures. In general, lower subsurface deformed layer thickness and burr formation at the hole entrance were obtained under cryogenic conditions. However, experimental results showed that cryogenic cooling increased the thrust force and the torque values and led to rapid tool wear. Therefore, burr formation at the hole exit also increased. Good surface roughness and low tool wear were achieved under wet conditions.Conclusion: Due to absence of any cooling/lubrication media, dry conditions led to higher cutting force, torque, and temperatures and undesirable surface quality. The test results showed that although it is possible to obtain better surface quality under cryogenic conditions, extremely low temperatures affected the cutting performance adversely. On the other hand, due to its moderate cooling and lubrication properties, wet conditions provided more stable cutting and better drilling performance.