Abstract Cryogenic assisted machining is experiencing growing popularity and acceptance as a toxic-free, eco-friendly, hazardless process producing improved structural components. This article deals with the analysis of 3D and 2D roughness profiles, surface morphology, residual stress and microhardness of 55NiCrMoV7 die steel after end milling operation under dry, wet, cryogenic CO2 and LN2 cooling environments. Among different cooling methods, the cryogenic CO2 was seen enhancing the surface topography and morphology due to the presence of minimal wear track. The result indicates the production of an insignificant amount of residual stress in the machined surface by the cooling environments at a spindle speed of 1989 rpm and feed rate of 0.02 mm/rev. The surface microhardness values were higher under cryogenic conditions compared to dry and wet conditions. Cryogenic LN2 provided the highest microhardness value among the four cooling methods.

中文翻译：

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低温环境下55NiCrMoV7模具钢端铣表面完整性研究

摘要 低温辅助加工作为一种无毒、环保、无害的生产改进结构部件的工艺，正日益受到欢迎和接受。本文涉及在干、湿、低温 CO2 和 LN2 冷却环境下端铣操作后 55NiCrMoV7 模具钢的 3D 和 2D 粗糙度轮廓、表面形貌、残余应力和显微硬度的分析。在不同的冷却方法中，由于存在最小的磨损痕迹，低温 CO2 增强了表面形貌和形态。结果表明，在主轴转速为 1989 rpm 和进给速率为 0.02 mm/rev 的情况下，冷却环境在加工表面上产生了微不足道的残余应力。与干湿条件相比，低温条件下的表面显微硬度值更高。在四种冷却方法中，低温 LN2 提供了最高的显微硬度值。