Improvements of machinability of aerospace-grade Inconel alloys with ultrasonically assisted hybrid machining
Improvements of machinability of aerospace-grade Inconel alloys with ultrasonically assisted hybrid machining
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DOI：
10.1007/s00170-018-3012-8
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发表时间：
2019-04-01
影响因子：
3.4
通讯作者：
Silberschmidt, Vadim V.
中科院分区：
文献类型：
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作者：
Bai, Wei;Bisht, Anuj;Silberschmidt, Vadim V.
航空航天级镍基合金，如英科乃尔718和625，由于其在高温下的优异机械性能，广泛应用于航空航天工业。然而，这些材料被归类为“难以加工”，因为它们具有高剪切强度、低导热性、易加工硬化以及微观结构中存在碳化物颗粒，导致刀具快速磨损。加工残余应力是一个重要的评估参数，它可以用来评估零件的整体结构弹性及其在使用中疲劳失效的倾向。超声辅助车削（UAT）是一种混合加工技术，它通过在切削过程中对刀具运动施加超声振动（典型频率类似于20kHz）来改变刀具与工件的接触条件。一些研究成功地证明了由此产生的切削力和表面形貌的改善。然而，对uat诱导的残余应力的深入研究是缺失的。在本研究中，采用常规车削（CT）和UAT两种不同的加工参数加工Inconel 718和625，研究了切削力、表面粗糙度和加工零件残余应力的影响。研究表明，当切削速度低于临界水平时，与连续油管相比，UAT可以显著降低切削力，改善表面粗糙度。加工后工件的残余应力表明，UAT比CT产生更多的压应力。因此，UAT显示了铬镍铁合金可加工性的全面改善。
Aerospace-grade Ni-based alloys such as Inconel 718 and 625 are widely used in the airspace industry thanks to their excellent mechanical properties at high temperatures. However, these materials are classified as difficult-to-machine' because of their high shear strength, low thermal conductivity, tendency to work-harden and presence of carbide particles in their microstructure, which lead to rapid tool wear. Machining-induced residual stresses in a machined part is an important parameter which is assessed since it can be used to evaluate overall structural resilience of the component and its propensity to fatigue failure in-service. Ultrasonically assisted turning (UAT) is a hybrid machining technique, in which tool-workpiece contact conditions are altered by imposing ultrasonic vibration (typical frequency similar to 20kHz) on a tool's movement in a cutting process. Several studies demonstrated successfully the resulting improvements in cutting forces and surface topography. However, a thorough study of UAT-induced residual stresses is missing. In this study, experimental results are presented for machining Inconel 718 and 625 using both conventional turning (CT) and UAT with different machining parameters to investigate the effect on cutting forces, surface roughness and residual stresses in the machined parts. The study indicates that UAT leads to significant cutting force reductions and improved surface roughness in comparison to CT for cutting speeds below a critical level. The residual stresses in machined workpiece show that UAT generates more compressive stresses when compared to those in CT. Thus, UAT demonstrates an overall improvement in machinability of Inconel alloys.