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Project

Process control and basic mechanisms in Multi-Material Laser Additive Manufacturing of Cu/Ni-alloy/Steel System

Currently, direct net shaping of metal parts is one of the hot topics in Laser Additive Manufacturing (LAM) with two main development directions: Laser Melting Deposition (LMD) and Selective Laser Melting (SLM). LMD is based on the laser powder feeding method, showing the superior capability in printing large-sized 3D parts, while its working accuracy of parts is relatively lower than the parts from SLM; SLM is based on the laser powder bed approach and it is expert in fabricating small-sized complex structures, including thin walls, micro configurations, fine internal channels, etc. Functionally Graded/Gradient Materials (FGMs) are materials which gradually change in material composition or microstructure along a specific dimension. FGMs are promising to be tailored to serve specific purposes and the gradual change in properties leads to lower residual stresses while increases durability. Based on SLM process, FGMs with right materials at right places could be processed which cannot be realized through traditional techniques especially when geometries of parts tend to be complex, showing great superiority in various fields, like industry, aerospace, automobile, etc. Nickel-based superalloys (like Inconel 718 and Inconel 625) are widely used as high-temperature service parts in various fields such as automatic and aerospace in which perfect combination of elevated temperature workability and mechanical performance are required. Cu, as a good material with high thermal conductivity, is the right material to increase the thermal conductive ability of Cu/Ni-alloy materials if Cu could be bonded well with Ni-alloy. Based on the previous researches of FGMs, SLM shows great potential to fabricate Cu/Ni-alloy two-material FGMs. Further, Cu/Ni-alloy/Steel three-material FGMs are believed to be the next goal based on the researches of Cu/Ni-alloy material. A good example of Cu/Ni-alloy/Steel system is Cu/Inconel 625/H13-steel, a new kind of mould material, in which Inconel 625 is taken as the interlayer to increase the bonding ability between Cu and H13-steel. The PhD program of Mr. Qimin SHI will focus on the process control and basic mechanisms in Multi-Material Laser Additive Manufacturing of Cu/Ni-alloy/Steel system. The possible future work will be the following aspects: (1) The first part is process optimization for hard-to-process materials, including increasing the laser absorptivity of Cu as to improve the machinability of Cu in SLM, lowering the temperature gradient of Ni-alloy (like Inconel 718 and Inconel 625) in SLM as to decrease the possibility of cracks in SLM-processed Ni-alloy parts as well as investigate the forming mechanisms of SLM-processed Cu parts or Inconel 718 parts with less defects and residual stress. This part of work aims to lay a solid foundation for the SLM process of Cu/Ni-alloy two-material FGMs. (2) Gradient & multi-phase interface of Cu/Ni-based alloy. The second part of Qimin’s PhD program is to design & process & optimize the interface between Cu and Ni-alloy in order to have a good understanding of internal mechanisms in SLM process of Cu/Ni-alloy two-material FGMs, especially its forming mechanism of gradient & multi-phase interface of Cu/Ni-based alloy. (3) The third part is to process Cu/Ni-alloy/Steel three-material FGMs via SLM, including choosing right materials of Ni-alloy and steel with specific purposes, optimizing the thickness of interlayer, etc. The final goal of Qimin’s PhD program is to successfully process Cu/Ni-alloy two-material FGMs and Cu/Ni-alloy/Steel three-material FGMs, providing scientific support for SLM of Multi-Material Laser Additive Manufacturing.

Date:1 Oct 2018 →  13 Jan 2020
Keywords:Multi-Material Laser Additive Manufacturing, Selective Laser Melting (SLM), Cu, Ni-based alloy, Steel
Disciplines:Control systems, robotics and automation, Design theories and methods, Mechatronics and robotics, Computer theory, Manufacturing engineering, Other mechanical and manufacturing engineering, Product development
Project type:PhD project