Powder bed-based laser beam melting (PBF-LB) for the production of tailored microstructures in quenched and tempered steel 42CrMo4

基于粉床的激光束熔化 (PBF-LB)，用于在调质钢 42CrMo4 中生产定制微观结构

• 批准号: 516837935
• 负责人: Dr.-Ing. Stefan Dietrich
• 金额: --
• 依托单位: Institut für Angewandte Materialien - Werkstoffkunde (IAM-WK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/516837935?language=en
• 关键词: Powder; bed; based; laser; beam

Quenched and tempered steels form a significant proportion of the world's annual steel production (16-18%) and can now be found in many automotive, aerospace and mechanical engineering components such as shafts, gears and other higher strength structural parts. Nevertheless, the production of optimised components from quenched and tempered steels using additive manufacturing methods (e.g. laser beam-based powder bed fusion - PBF-LB) and research into resulting material and component states has made little progress. The reasons for this are mainly to be found in difficulties in consolidation from the metal powder by the laser exposure process. Quenched and tempered steels are generally considered difficult to weld due to their higher carbon content. Also in the PBF-LB process, similar to microwelding, high cooling rates occur in the weld and heat-affected zone due to the local energy input and the associated self-quenching. The thermal and transformation-related strains induced by the cooling rates lead to strong component distortion. The martensitic transformation in the weld zone also increases the probability of cracking. The probability of crack formation can be reduced during the process by using a heated build plate. However, the mechanical properties in the "as-built" state do not usually correspond to the technical specifications from the application. In addition, the downstream heat treatment is time-consuming and cost-intensive. The core of the project is therefore to control the intrinsic transformation and tempering effects occurring in the PBF-LB process and to use them specifically to integrate the conventional and otherwise downstream heat treatment directly in the PBF-LB process. In addition to the microstructural and mechanical characterisation, the present research proposal will use a phase-specific thermal-mechanical FE simulation to investigate the influence of novel exposure strategies with regard to a stress-appropriate, integrated and local heat treatment in the process. To validate the simulation, an in-situ characterisation of the process at the synchrotron is also planned. In this way, an important research gap in the field of additive manufacturing of heat-treatable steels will be closed.

淬火和回火钢在世界钢年产量中占很大比例（16-18%），现在可以在许多汽车，航空航天和机械工程部件中找到，如轴，齿轮和其他更高强度的结构部件。然而，使用增材制造方法（例如基于激光束的粉末床熔合- PBF-LB）从淬火和回火钢生产优化的部件以及对所得材料和部件状态的研究进展甚微。其原因主要在于通过激光曝光工艺从金属粉末固结的困难。淬火和回火钢由于其较高的碳含量而通常被认为难以焊接。同样在PBF-LB工艺中，类似于微焊接，由于局部能量输入和相关的自淬火，在焊接和热影响区中出现高冷却速率。由冷却速率引起的热应变和相变应变导致强烈的成分畸变。焊接区的马氏体相变也增加了裂纹的可能性。通过使用加热的构建板，可以在该过程期间降低裂纹形成的可能性。然而，“竣工”状态下的机械性能通常不符合应用的技术规格。此外，下游热处理是耗时且成本密集的。因此，该项目的核心是控制PBF-LB工艺中发生的内在转变和回火效应，并专门将其用于将常规和其他下游热处理直接集成到PBF-LB工艺中。除了微观结构和机械特性，本研究建议将使用特定阶段的热机械有限元模拟，以调查新的曝光策略的影响，在这个过程中的应力适当的，集成的和局部的热处理。为了验证模拟，在同步加速器的过程中的原位表征也计划。通过这种方式，将填补热处理钢增材制造领域的一个重要研究空白。