Surface integrity evolution and machining efficiency analysis of W-EDM of nickel-based alloy
Surface integrity evolution and machining efficiency analysis of W-EDM of nickel-based alloy
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DOI：
10.1016/j.apsusc.2014.05.165
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发表时间：
2014-09
影响因子：
6.7
通讯作者：
Li Li-Li;X. T. Wei;Zongwen Li
中科院分区：
文献类型：
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作者：
Li Li-Li;X. T. Wei;Zongwen Li
镍基合金因其优异的性能在许多行业有着广泛的应用。然而，由于导热系数低、应变硬化强、高温下强度高，使用切削和磨削方法进行机械加工非常困难。放电加工是一种通过电腐蚀加工镍基合金的替代竞争工艺。本研究重点研究了 W-EDM 在加工 IN 718 时的表面完整性和加工效率的演变过程，采用一种粗切削 (RC) 模式和三种修整切削 (TC) 模式。材料去除效率、表面粗糙度、表面形貌、表面合金化和显微硬度已得到表征。结果表明，W-EDM 可以实现高材料去除效率。 RC 模式下 Ra 的六西格玛分布与 TC 模式下不同。 IN 718 的高韧性是 TC 模式中不存在微裂纹的主要因素。微裂纹仅存在于白色层中。在 RC 模式下可以观察到带有微裂纹的厚白色层 (6–8 µm)，在 TC2 模式下可以观察到没有这些缺陷的非常薄的白色层 (0–2 µm)，而在 TC3 模式下白色层几乎看不见。 TC模式白层显微硬度高于MC模式。
Nickel-based alloys have wide applications in many industries due to their outstanding properties. However, it is very difficult to machine using cutting and grinding methods because of their low thermal conductivity, strong strain hardening, and high strength at elevated temperatures. Electrical discharge machining is an alternative competitive process to machine Nickel-based alloys by electrical erosion. This study focuses on the evolution process of surface integrity and machining efficiency of W-EDM in machining IN 718 by one rough cut (RC) mode followed by three trim cut (TC) modes. Material removal efficiency, surface roughness, surface topography, surface alloying, and microhardness have been characterized. Results show that high material removal efficiency can be achieved in W-EDM. Six-sigma distribution of Ra in RC mode is different from that of TC modes. The high toughness of IN 718 would be the major contributing factor to the absence of microcracks in the TC modes. Microcracks just exist in the white layer. Thick white layers (6–8 μm) with microcracks in RC mode and very thin white layers (0–2 μm) free of those defects in TC2 mode can be observed, while white layer is nearly invisible in TC3 mode. The microhardness of white layer in TC mode is higher than that in MC mode.