Nickel-based superalloy Inco nel 718 has many excellent properties such as high strength, oxidation resistance, radiation resistance, weldability and structural stability. It is widely used in gas turbines, aero engines, nuclear reactors and other high temperature fields. At the same time, due to the serious self-hardening of its own processing, the use of conventional mechanical processing methods is likely to cause serious tool wear, poor heat resistance and surface integrity of the material. The rapid heating and rapid solidification characteristics in the laser processing process make the fabricated metal parts have directional growth microstructure and excellent performance, and have broad application prospects in the preparation of aerospace devices, aircraft engine blades and weapon parts; Axial powder feeding can deposit different components of forming materials according to performance requirements in different parts of the part, so as to optimize the structural design, weight, strength and material use of the parts. Laser metal deposition forming technology can also be used to prepare the function. Composite materials such as gradient materials, which are widely used in electronics, aerospace and other fields. [Introduction] Recently, Guo Weiguo (corresponding author) of Northwestern Polytechnical University and others are in the journal Mater. Sci. Eng. An article published in the latest study entitled "Influence of Process Parameters and Heat Treatments on the Microstructures and Dynamic Mechanical Behaviors of Inco nel 718 Superalloy Manufactured by Laser me tal Deposition". In order to prepare high-performance nickel-base superalloys for aero-engines using laser metal deposition (LMD) technology, Inco nel 718 alloys were prepared by three different process parameters using LMD technology and heat treated by two different heat treatment systems. The effects of process parameters and heat treatment on its microstructure and dynamic mechanical properties were then evaluated by compression tests with wide strain rate and temperature range, and the initial microstructure and fracture characteristics of the samples were observed using optical microscopy and scanning electron microscopy. figure 1. Schematic diagram of laser metal deposition process figure 2. Different sample microstructure (a) Deposited sample 1 microstructure (b) deposition sample 2 microstructure (c) deposition sample 3 microstructure (d) Microstructure of initial defects in the sample image 3. (a) direct aging treatment and (b) sample microstructure after standard heat treatment Figure 4. The variation of flow stress with temperature under different strain rates Figure 5. Profile and fracture behavior of laser deposited Inco nel 718 after compression in (a) X direction and (b) Z direction Figure 6. Fracture behavior of laser deposited Inco nel 718 after dynamic compression in Z direction Figure 7. Fracture morphology of laser deposited Inco nel 718 alloy after compression in the Z direction at a strain rate of 5300/s and a temperature of 298K (a) and (b) fracture morphology of as-deposited Inco nel 718 alloy (c) and (d) fracture morphology of direct aging Inco nel 718 alloy (e) and (f) fracture morphology of standard heat-treated Inconal 718 alloy ã€summary】 In this paper, the nickel-base superalloy Inco nel 718 used in aeroengines is prepared by laser metal deposition (LMD) technology using different process parameters and heat treatment system. Compressive experiments at different strain rates (0.001 - 5300 / s) and temperatures (273-1193K) were performed on each set of laser deposited Inco nel 718 samples to evaluate the microstructure and dynamics of the process parameters and heat treatment methods. The impact of performance. At the same time, the initial microstructure and fracture characteristics of the sample were observed using an optical microscope and a scanning electron microscope. The results show that in the laser additive manufacturing process, a higher energy input density results in a wider dendrite spacing. As the primary dendrite spacing increases, the plastic flow stress of the alloy decreases approximately linearly. The plastic flow stress of laser deposited Inco nel 718 alloy has an abnormal stress peak phenomenon with the increase of temperature, which is a typical characteristic of the third type strain aging phenomenon. Finally, by observing the compression failure characteristics, it is found that the propagation path of the crack depends on the compression loading direction. The compression fracture morphology can reflect the effect of heat treatment on the plasticity of the specimen. In addition, initial defects (pores and shrinkage pores, etc.) generated during laser deposition may cause initiation, deflection and branching of dynamic cracks. Bitmain is the world's leading digital currency mining machine manufacturer. Its brand ANTMINER has maintained a long-term technological and market dominance in the industry, with customers covering more than 100 countries and regions. The company has subsidiaries in China, the United States, Singapore, Malaysia, Kazakhstan and other places.
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