Abstract Machining processes with main thermal impact like electro discharge machining (EDM) result in a change of temperature in the workpiece with temporal and spatial temperature gradients which have a large influence on the thermo-chemically modified surface microstructure and therefore a high impact on the functional properties of the workpiece. However, as most state variables (like the temperature) cannot be measured directly during processing, further insight can be gained only by simulations. This problem can be addressed by using microstructural features like the secondary dendrite arm spacing for calculating the cooling rate and by validating the simulated temperature profiles with these values. This study analyzes the subsurface microstructure of EDM machined 42CrMo4 steel with a ferrite-perlite and a quenched-tempered matrix by a range of microstructure analysis techniques. Results of electron backscatter diffraction (EBSD), electron probe microanalysis (EPMA) and analysis of secondary dendrite arm spacing of secondary electron images are presented and their dependence on the main processing parameters is discussed qualitatively and quantitatively.

中文翻译：

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电火花加工热化学改性表面区域的电子显微表征

摘要 电火花加工 (EDM) 等具有主要热影响的加工工艺会导致工件温度随时间和空间温度梯度发生变化，这对热化学改性的表面微观结构有很大影响，因此对工件的功能影响很大。工件的特性。然而，由于大多数状态变量（如温度）在处理过程中无法直接测量，因此只能通过模拟获得进一步的了解。这个问题可以通过使用微观结构特征（如二次枝晶臂间距）来计算冷却速率并通过这些值验证模拟温度曲线来解决。本研究通过一系列显微组织分析技术分析了电火花加工 42CrMo4 钢与铁素体-珍珠岩和淬火回火基体的次表面显微组织。介绍了电子背散射衍射 (EBSD)、电子探针微量分析 (EPMA) 和二次电子图像二次枝晶臂间距分析的结果，并定性和定量地讨论了它们对主要处理参数的依赖性。