Brazeability of similar hybrid joint compounds consisting of additively manufactured and conventional material grades

选择性激光熔化（SLM）是一种基于金属粉末的制造工艺，为生产高度复杂的部件提供了最佳的设计选择。直到今天，在简单的几何形状上生成SLM部件，常规生产的部件需要在实现混合接头化合物之前对这些部件进行分段、钎焊和回火。这种方法的缺点主要在于SLM部件包含高残余应力并且在生成状态下具有完全不同的材料结构。因此，这些化合物提供完全不同的机械-技术性能。此外，技术上高效的SLM部件需要后续的热处理，这将本已复杂的生产链扩展为另一个工艺步骤。选择性激光熔化以及组合钎焊/热处理工艺提供了巨大的潜力，可以将各自的优势联合收割机组合成高效的生产链。如在初步测试中所证明的，残余孔隙和氧化物夹杂物显著影响钎焊质量和接头强度，尽管SLM材料具有高于99.8体积%的密度。该研究项目将系统地产生基础知识，以钎焊奥氏体不锈钢316L（X2 CrNiMo 17 -12-2）和镍马氏体时效工具钢18 Ni 300（X3 NiCoMoTi 18 -9-5）的常规和SLM材料等级的类似复合材料和混合复合材料。此外，钎焊接头将以仅通过选择性激光熔化制造的适当复合材料为基准。此外，将对接头进行热处理，以均衡微观结构并最大限度地减少残余应力。总体目标是建立一个合适的工艺链，以生产类似的SLM和常规材料的混合复合材料，这是基于机械接头性能的特征值。详细地说，研究项目的重点主要是使用这些材料等级的钎焊工艺的研究。建立钎焊工艺为传统的复合材料被转移到这些复合材料和分析的润湿和流动行为，接头强度，具有强烈的关注SLM材料内的孔隙和氧化物的钎焊质量的影响。此外，将对钎焊样品进行气相蚀刻，然后对连接表面进行镀镍。这些工艺将去除氧化物并封闭开孔，从而显著提高钎焊质量和接头强度。

Selective-Laser-Melting (SLM) is a metal-powder-based manufacturing process that offers the best possible design options for the production of highly complex components. Until today, generating a SLM part on a simple geometrical, conventionally produced component requires such components to be segmented, brazed and tempered prior to realizing a hybrid joint compound. The disadvantages of this procedure are mainly based on the fact that the SLM part contains high residual stresses and has a completely different material structure in the generated state. Therefore, these compounds offer wholly dissimilar mechanical-technological properties. Furthermore, technically efficient SLM components require a subsequent heat treatment which extends the already complex production chain by another process step.Selective laser melting as well as a combined brazing/heat treatment processes offer a great potential to combine the respective advantages into an efficient production chain. As proven in preliminary tests, the residual porosity and oxide inclusions affect the brazing quality and the joint strength significantly, although the SLM materials had a density higher than 99.8 vol.-%. This research project will systematically generate fundamental knowledge to braze similar composite and hybrid composites of conventional and SLM material grades for austenitic stainless steel 316L (X2CrNiMo17-12-2) and nickel maraging tool steel 18Ni300 (X3NiCoMoTi18-9-5). Furthermore, the brazed joints will be benchmarked to appropriate composites which are only manufactured by selective laser melting. Additionally, the joints will be heat-treated to equalize the microstructure and minimize residual stresses. The overall objective is to establish a suitable process chain to produce similar hybrid composites of SLM and conventional materials, which is based on characteristic values of the mechanical joint properties. In detail, the focus of the research project is mainly the investigation of the brazing process using these material grades. The established brazing processes for conventional composites are transferred to these composites and analyzed with respect to the wetting and flow behavior, the joint strength, with a strong focus on the influence of pores and oxides within the SLM material to the brazing quality. In addition, gas phase etching followed by nickel plating of the joining surfaces will be examined for the brazing samples. These processes will remove the oxides and close the open porosity, thus enhancing the brazing quality and the joint strength significantly.