Comparative Microstructural Analysis of Aluminum Alloy 7075 Under Dry and Chilled Air Drilling Conditions

Aluminum Alloy 7075 (AA 7075) is renowned for its high strength-to-weight ratio and is widely used in the aerospace, automotive, and marine industries. However, during drilling, the machinability becomes challenging due to frequent tool changes, serious burr formation, and poor chip evacuation. Additionally, the alloy is prone to microstructural changes that can compromise its mechanical properties. Meanwhile, although effective, traditional petroleum-based cutting fluids are used widely in machining processes to alleviate machinability problems, raising significant environmental and health concerns. To address this, the study explores eco-friendly alternatives, specifically dry and chilled air cutting in the drilling process. The objective is to evaluate the impact of these cutting conditions on the microstructure and hardness of this material. The research employs advanced methodologies, including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vickers hardness testing to analyze crystallinity, phase transformation, grain size, strain, and residual stress. Results revealed that applying chilled air cutting enhances crystallinity, refines grain structure, reduces strain, and improves hardness compared to dry cutting. These findings aim to optimize machining parameters, ensuring the preservation of material properties while promoting environmental sustainability.