Structuring by laser remelting for removing waviness or generation of structures on metallic surfaces

RWTH亚琛大学数字添加剂生产DAP教席正在研究一种构建金属表面结构的新工艺。这种结构化不是基于材料的烧蚀，而是基于材料的重新分布。再分布是通过调制激光功率的激光重熔来实现的。这种创新工艺的特点和优点是：-制造特别是具有小粗糙度、微米至毫米波长和高度为2至500微米的周期性结构-不烧蚀材料的结构-通过构建反向结构(“破坏性干涉”)从其他制造过程中去除波浪度或结构的可能性-在一个加工步骤中结构和激光抛光-化学成分的均质化和在表层中产生细晶结构并因此增强表面的性能，例如关于耐腐蚀性或硬性。可能的应用是添加制造(印刷部件的后处理)、机械工程(碾磨精密部件的后处理)、工具制造(设计面、可重写金属部件)、航空(流体力学)和珠宝(设计面)。然而，由于这一过程的新颖性，仍有许多基本的科学问题需要回答：-完全理解结构形成的潜在机制。1.2379钢合金的一个相反的悖论行为表明，其工艺原理还没有完全被理解--“逆问题”：到目前为止，主要是激光功率的调制是不同的，并研究了由此产生的结构。获得所需的表面结构所需的调制只进行了很少的研究，并且仅针对周期结构--到目前为止，仅针对一维正弦结构研究了通过“相消干涉”去除结构和波纹的问题。2维窦和非周期结构的去除尚未被研究-结果在其他金属材料上的转移和对结构形成的热物理材料特性的影响的研究-通过重熔的结构建模，以研究熔体和凝固速率、从固体到液体的体积变化和表面张力对所产生的结构的影响-关于小结构(波长和lt；100微米)和面积速率的工艺限制的扩展。物理原理在多大程度上限制了结构化过程？熔池是否太小或激光调制太快，无法形成结构？-通过激光重熔在简单3D几何图形上的3D表面(入射角，分区边界)进行结构研究这些科学问题将在应用项目中由RWTH亚琛大学的DAP主席和莫斯科国家航空技术研究所密切合作进行研究。

The Chair for Digital Additive Production DAP of RWTH Aachen University is investigating a new process for structuring metallic surfaces. The structuring is not based on ablation of material but on redistribution of material. The redistribution is achieved by laser remelting with modulated laser power. Characteristics and advantages of this innovative process are:- Manufacturing especially of periodic structures with small roughness, µm- to mm-wavelengths and heights of 2 to 500 µm- Structuring without ablation of material - Possibility for removing the waviness or structures from other manufacturing processes by structuring the inverse structure (“destructive interference”)- Structuring and laser polishing in one processing step- Homogenization of the chemical composition and generation of a fine grain structure in the surface layer and therefore enhancing the properties of the surface, e.g. regarding corrosion resistance or hardnessPossible applications are additive manufacturing (post processing of printed parts), mechanical engineering (post processing of milled precision parts), tool making (design surfaces, rewriteable metallic parts), aeronautics (fluid mechanics) and jewelry (design surfaces). However, due to the novelty of the process there are still many fundamental scientific questions to be answered:- Complete comprehension of the underlying mechanisms for structure formation. A paradox opposite behavior of steel alloy 1.2379 suggests that the process principle is not yet fully understood- “Inverse Problem”: Up to now mainly the modulation of the laser power was varied and the resulting structures were investigated. Which modulation is required to achieve a desired surface structure is only slightly investigated and only for periodic structures- Up to now the removing of structures and waviness by “Destructive Interference” is only investigated for 1-dimensional sinusoidal structures. The removing of 2-dimensional sinus and also aperiodic structures is not investigated yet- Transfer of the results on further metallic materials and investigation of the influence of the thermo-physical material properties on the structure formation- Modeling of structuring by remelting for investigating the influence of melt and solidification rate, volume change from solid to liquid and surface tension on the resulting structures- Extension of the process limits regarding small structures (wavelength < 100 µm) and area rate. At what point do physical principles limit the structuring process? Can a melt pool be too small or laser modulation too fast for structure formation?- Investigation of structuring by laser remelting for 3D surfaces (angle of incidence, borders between subareas) on simple 3D geometriesThese scientific questions shall be investigated in the applied project in a close collaboration between the chair DAP of RWTH Aachen University and the National Institute of Aviation Technologies NIAT in Moscow.