Fatigue strength of by selective laser melting generated samples

选择性激光熔化产生的样品的疲劳强度

• 批准号: 275999847
• 负责人: Professorin Dr.-Ing. Brigitte Clausen, since 6/2021
• 金额: --
• 依托单位: BIAS - Bremer Institut für Angewandte Strahltechnik GmbH
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/275999847?language=en
• 关键词: Fatigue; strength; selective; laser; melting

Additive manufacturing processes promise to be time and cost saving compared to conventional manufacturing processes, especially for components manufactured in small batches. During the Selective Laser Melting process, one-component metals and alloys in powder form are processed in layers. The process belongs to the class of completely melting additive manufacturing processes in which the powder is completely remelted, whereby a melting metallurgical bond is formed between the individual layers. An obvious criterion for the quality of a component manufactured by SLM is its density in comparison to the base material. A component which is free of pores and cracks is desired. Furthermore, the mechanical properties are of interest. There are only a few systematic investigations, especially for the mechanical properties at cyclic loading. The large number of influencing variables in the process and their interaction with each other complicate a priori estimation with regard to the process window and the resulting properties of the samples.The investigations carried out during the first funding phase on steels 1.4404 and 1.2344 have shown that the causes of failure of SLM-generated materials cannot be reduced to the existing residual porosity after an improvement of the surface quality. The specimens failed in the steel matrix itself as well. Thus high fatigue strength cannot be coupled exclusively to the avoidance of residual porosity. The aim of the project is to realize homogeneous mechanical properties of SLM-generated components of highest fatigue strength. By reliably detecting transient temperature fields and the melt pool characteristics, the influences and the reaction of parameter shifts in the process are to be quantified and used as a basis for the design of a control concept. Over a constant temperature history, homogeneous sample properties with maximized fatigue strength are to be achieved. Simultaneously, different heat treatments of the manufactured parts are to be carried out in order to remove undesirable residual stresses for austenitic steel 1.4404 and tool steel 1.2344. In addition, a new hardening process adapted to the initial state of the specimens is to be developed for tool steel 1.2344 to achieve a homogeneous microstructure in order to further improve its fatigue strength. Furthermore, the fatigue strength of SLM-manufactured specimens before and after heat treatment is to be modelled using different modelling approaches in order to enable the prediction of fatigue strength.

与传统制造工艺相比，增材制造工艺有望节省时间和成本，特别是对于小批量制造的组件。在选择性激光熔化过程中，粉末形式的单组分金属和合金被分层加工。该工艺属于完全熔融增材制造工艺的类别，其中粉末完全再熔融，由此在各个层之间形成熔融冶金结合。SLM制造的部件质量的一个明显标准是其与基材相比的密度。期望没有孔和裂纹的部件。此外，机械性能也令人感兴趣。目前，对混凝土的力学性能，特别是循环荷载下的力学性能的研究还很少。工艺中的大量影响变量及其相互作用使关于工艺窗口和样品的所得性质的先验估计复杂化。在第一资助阶段对钢1.4404和1.2344进行的研究表明，SLM失效的原因是：产生的材料在表面质量改善后不能减少到现有的残余孔隙。试样在钢基体本身中也失效。因此，高疲劳强度不能仅与避免残余孔隙相关联。该项目的目的是实现SLM产生的最高疲劳强度部件的均匀机械性能。通过可靠地检测瞬态温度场和熔池特性，可以量化过程中参数变化的影响和反应，并将其用作控制方案设计的基础。在恒定的温度历史中，将实现具有最大疲劳强度的均匀样品特性。同时，对制造的零件进行不同的热处理，以消除奥氏体钢1.4404和工具钢1.2344的不希望的残余应力。此外，一个新的硬化工艺适合于试样的初始状态是开发工具钢1.2344，以实现均匀的显微组织，以进一步提高其疲劳强度。此外，SLM制造的试样在热处理前后的疲劳强度将使用不同的建模方法进行建模，以便能够预测疲劳强度。