Yanmin Li

Laser near net shape manufacturing for nickel alloy parts with complex structure

To fabricate near net-shape nickel alloy turbine blade airfoil with complex internal structure, process of laser net shape manufacturing (LNSM) is studied in two aspects. One is steady process analysis to establish transfer functions between dimension and process parameters. Another one is dynamic process analysis focusing on decreasing defects in the region of special geometry features. Two solutions, path planning with process parameters optimization and vision based closed loop control are implemented to keep the process stable in those areas. Both solutions are applied successfully in nickel alloy turbine blade airfoil deposition with LNSM system. Geometric inspection shows good dimensional accuracy and surface quality can be achieved with this technology.To fabricate near net-shape nickel alloy turbine blade airfoil with complex internal structure, process of laser net shape manufacturing (LNSM) is studied in two aspects. One is steady process analysis to establish transfer functions between dimension and process parameters. Another one is dynamic process analysis focusing on decreasing defects in the region of special geometry features. Two solutions, path planning with process parameters optimization and vision based closed loop control are implemented to keep the process stable in those areas. Both solutions are applied successfully in nickel alloy turbine blade airfoil deposition with LNSM system. Geometric inspection shows good dimensional accuracy and surface quality can be achieved with this technology.

Laser net shape manufacturing of metallic materials with CO 2 and fiber laser

Laser net shape manufacturing of metallic materials has been carried out with CO2 and fiber lasers. The effect of the processing parameters, such as laser power, scanning velocity, and spot size on the impact of final deposition result was investigated. A comparison study of the as-deposited materials with the use of the two lasers was also conducted. It was found that the alignment of powder stream and laser beam is a critical element of ensuring high quality of deposition.Laser net shape manufacturing of metallic materials has been carried out with CO2 and fiber lasers. The effect of the processing parameters, such as laser power, scanning velocity, and spot size on the impact of final deposition result was investigated. A comparison study of the as-deposited materials with the use of the two lasers was also conducted. It was found that the alignment of powder stream and laser beam is a critical element of ensuring high quality of deposition.

Laser net shape manufacturing of Ti6Al4V

Ti6Al4V is the most common used Ti alloy due to its outstanding comprehensive properties. In order to investigate the process of Laser Net Shape Manufacturing (LNSM) with Ti6Al4V, systematic experimental studies were performed with CO2 laser. The process window and transfer functions of the LNSM process were developed. It was shown that the power mass ratio is a critical factor to achieve good geometry and surface finish of LNSM Ti6Al4V part. The 3D Ti6Al4V parts were deposited with good geometry and surface finish with the parameters selected through the transfer functions. The microstructure of deposited Ti6Al4V samples were mainly made up of mixed fine α and β phase, which indicated good comprehensive properties of deposited samples. The testing results show that the tensile properties of LNSM samples are better than casting data and comparable with forging data of Ti6Al4V.Ti6Al4V is the most common used Ti alloy due to its outstanding comprehensive properties. In order to investigate the process of Laser Net Shape Manufacturing (LNSM) with Ti6Al4V, systematic experimental studies were performed with CO2 laser. The process window and transfer functions of the LNSM process were developed. It was shown that the power mass ratio is a critical factor to achieve good geometry and surface finish of LNSM Ti6Al4V part. The 3D Ti6Al4V parts were deposited with good geometry and surface finish with the parameters selected through the transfer functions. The microstructure of deposited Ti6Al4V samples were mainly made up of mixed fine α and β phase, which indicated good comprehensive properties of deposited samples. The testing results show that the tensile properties of LNSM samples are better than casting data and comparable with forging data of Ti6Al4V.

Laser net shape manufacturing of Rene80

Rene 80, as an alloy for production of the jet turbine blades by investment precision casting, shows high mechanical properties as well as microstructure stability during the high temperature engine operation. However, due to poor weldability of this material, it’s very difficult to weld by conventional welding technologies. Laser beam welding/cladding has been recognized as a very attractive and promising technology for prototype fabrication and repair of high performance aircraft engine components due to its lower heat input and localized heating. In this paper, Laser Net Shape Manufacturing (LNSM) was applied for Rene 80 deposition. The key processing parameters were correlated with solidification microstructure and cracking susceptibility was investigated. In addition, the effect of heat treatment on the microstructure was also studied.Rene 80, as an alloy for production of the jet turbine blades by investment precision casting, shows high mechanical properties as well as microstructure stability during the high temperature engine operation. However, due to poor weldability of this material, it’s very difficult to weld by conventional welding technologies. Laser beam welding/cladding has been recognized as a very attractive and promising technology for prototype fabrication and repair of high performance aircraft engine components due to its lower heat input and localized heating. In this paper, Laser Net Shape Manufacturing (LNSM) was applied for Rene 80 deposition. The key processing parameters were correlated with solidification microstructure and cracking susceptibility was investigated. In addition, the effect of heat treatment on the microstructure was also studied.

A binocular vision system to measure width and height of deposited material in laser net-shape manufacturing

Laser Net-Shape Manufacturing (LNSM) is an effective way for aircraft part manufacturing and repair. The process usually requires a sensor and control system to increase geometry accuracy and enhance mechanical property. This article presents a novel vision sensor, which is able to measure meltpool width and deposition height simultaneously during laser consolidation process. It works based on the theory of binocular vision. The sensor forms two separate clear images of meltpool on a CMOS camera through a group of optics, and then a processor finds an accurate shift between two images by a couple of image processing algorithms. This shift can be calibrated to axial displacement, or Z-height. Each individual image, or combination of two images, can be used to measure meltpool width, because the sensor is installed almost coaxially.Laser Net-Shape Manufacturing (LNSM) is an effective way for aircraft part manufacturing and repair. The process usually requires a sensor and control system to increase geometry accuracy and enhance mechanical property. This article presents a novel vision sensor, which is able to measure meltpool width and deposition height simultaneously during laser consolidation process. It works based on the theory of binocular vision. The sensor forms two separate clear images of meltpool on a CMOS camera through a group of optics, and then a processor finds an accurate shift between two images by a couple of image processing algorithms. This shift can be calibrated to axial displacement, or Z-height. Each individual image, or combination of two images, can be used to measure meltpool width, because the sensor is installed almost coaxially.

Microstructure and mechanical properties of laser net shape manufactured Inconel 718 and TI-6AL-4V components

Laser net shape manufacturing (LNSM) is a laser cladding based technology, which can fabricate prototype and repair high performance aircraft engine components with metal powders. Characterizing mechanical properties of the laser net shape manufactured components is important to the application of LNSM technique in real production. Nickel-based superalloys and titanium alloys are the most commonly used materials in aircraft engines. This paper studies the material properties of laser deposited Inconel 718 and Ti-6Al-4V specimens by evaluation of their microstructures and tensile strength. The effects of laser processing parameters and build up orientations on the resulting material microstructures and the mechanical strengths are investigated.Laser net shape manufacturing (LNSM) is a laser cladding based technology, which can fabricate prototype and repair high performance aircraft engine components with metal powders. Characterizing mechanical properties of the laser net shape manufactured components is important to the application of LNSM technique in real production. Nickel-based superalloys and titanium alloys are the most commonly used materials in aircraft engines. This paper studies the material properties of laser deposited Inconel 718 and Ti-6Al-4V specimens by evaluation of their microstructures and tensile strength. The effects of laser processing parameters and build up orientations on the resulting material microstructures and the mechanical strengths are investigated.