Hipp Dominik, Mahrle Achim, Beyer Eckhard
Institute of Manufacturing Science and Engineering, TU Dresden, PO Box, D-01062 Dresden, Germany.
Fraunhofer IWS Dresden, Winterbergstraße 28, D-01277 Dresden, Germany.
Materials (Basel). 2019 Aug 30;12(17):2802. doi: 10.3390/ma12172802.
The industrial application of laser materials processing methods is still far ahead of research into the physical phenomena occurring during these processes. In particular, the effect of high temperatures on the energy coupling of laser irradiation of metals is poorly understood. However, most processes in laser materials treatment involve temperatures above the melting point or even cause evaporation. This study therefore evaluates the effect of high temperatures on the energy coupling efficiency of stainless steel experimentally for three typical laser wavelengths (515 nm, 1.07 µm, 10.6 µm). As a result, it is shown that the effect of temperature on the energy coupling efficiency depends on the wavelength. In this context the relevance of the X-point phenomenon known from the emissivity theory could be demonstrated for laser material processing. Further, the effect of a process-induced surface oxidation is analyzed. At temperatures above 650 °C the energy coupling efficiency dramatically increases to around 65% at melting point and stays at this high level even in the liquid phase.
激光材料加工方法的工业应用仍远远领先于对这些过程中发生的物理现象的研究。特别是，高温对金属激光辐照能量耦合的影响还知之甚少。然而，激光材料处理中的大多数过程涉及高于熔点的温度，甚至会导致蒸发。因此，本研究针对三种典型激光波长（515纳米、1.07微米、10.6微米），通过实验评估了高温对不锈钢能量耦合效率的影响。结果表明，温度对能量耦合效率的影响取决于波长。在此背景下，发射率理论中已知的X点现象在激光材料加工中具有相关性得到了证明。此外，还分析了加工引起的表面氧化的影响。在高于650℃的温度下，能量耦合效率在熔点时急剧增加至约65%，即使在液相中也保持在这一高水平。
