چكيده به لاتين
Machining nickel-based superalloys, such as Hastelloy X, presents significant challenges due to their high thermal stability, exceptional strength, and outstanding resistance to oxidation and corrosion. While these properties make them invaluable for critical applications in aerospace and petrochemical industries, they also reduce machinability, leading to severe tool wear, high cutting forces, and elevated thermal loads during machining. This study addresses these challenges by evaluating the comparative performance of advanced carbide tools and cubic boron nitride (cBN) tools under extreme machining conditions. It investigates how tool wear can be minimized and how tool life can be extended during the turning of this difficult-to-machine material while maintaining acceptable material removal rates and surface quality. To achieve this, systematic experiments were designed and executed, focusing on high-speed and high-feed-rate machining. Two types of tools—innovative carbide inserts and cBN tools with varying cBN content—were evaluated. Advanced analytical methods such as Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) were employed to study wear mechanisms, including abrasive, adhesive, and thermal fatigue wear. Additionally, Response Surface Methodology (RSM) was used to model the relationship between machining parameters (cutting speed, feed rate, depth of cut) and tool wear, enabling the determination of optimal machining conditions. Using MATLAB, optimal conditions that balanced material removal rates across tools with varying cutting parameters were further identified. The results provided significant insights into tool performance and wear behavior. Innovative carbide inserts demonstrated stable performance across a wide range of machining conditions, making them suitable for general-purpose applications. However, the performance of cBN tools varied depending on their cBN content. High-cBN-content tools experienced premature failure due to thermal and mechanical brittleness, regardless of cutting conditions. Conversely, low-cBN-content tools exhibited greater wear resistance and thermal stability but showed high sensitivity to cutting edge geometry. SEM and EDS analyses identified dominant wear mechanisms, with abrasive wear prevailing at higher cutting speeds and adhesive wear dominating at lower speeds. Optimal cutting conditions derived from the RSM models effectively reduced tool wear and extended tool life while maintaining high machining rates. This study not only highlights the limitations of existing tools but also provides practical insights for designing and utilizing advanced cutting tools for machining superalloys. By bridging the gap between tool material properties and extreme machining parameters, this research offers a pathway to improving productivity, reducing operational costs, and enhancing the machining efficiency of Hastelloy X.
