The major purpose of this study is to investigate two strategies for additive manufacturing processes of SS316L using the direct laser metal deposition method (DLMD). In additive manufacturing (AM), the influence of scanning patterns was the first strategy, and the other strategy was the effects of laser power reduction in various layers. The experiments used a semiconductor diode laser with a coaxial nozzle head. The goal of this study was to determine how these two techniques influenced the properties of additive-produced components. Geometrical metrics such as width, height, and penetration, as well as particle size, and microhardness profiles, were assessed in the macrosection of the fabricated wall samples. The sample’s height stability was also investigated. The results revealed that the scanning pattern significantly affects all aspects of additive-manufactured components. The results indicated that higher stability is achieved when using a unidirectional scanning sequence. The average particle size of specimens obtained using the unidirectional and bidirectional scanning patterns was 8.6 and 9.69 μm, respectively. The pattern of particle size variation in the samples demonstrates that the LMD walls in the beginning and end are larger than in the samples at the center, the microhardness fluctuation pattern is in the opposite direction of particle size. The width of the samples was also found to decrease as the laser power was reduced from the substrate upward.
Laser cladding is usually used for remanufacturing plate and shaft parts. Because the laser cladding process belongs to the energy loading process, it is inevitable to produce stress and plastic deformation, which will cause the parts to lose the original shape precision after the cladding. To reduce the deformation of the parts after laser cladding and reduce the workload of the processing parts, the influence of different laser scanning sequence methods on the deformation of the substrate is studied at this angle. Due to the very uneven distribution of the temperature field of the substrate during the laser irradiation, the uneven distribution of the temperature field will eventually cause the deformation of the cladding parts. To reduce the deformations of the parts after the cladding, we should make the temperature field distributed more evenly in the parts of the cladding process. Based on this theory, laser cladding of a stainless-steel plate for three different laser scanning sequence methods is studied. The results show that the scanning path significantly influences the temperature field and deformation of the part. The study’s main objective was to reduce the temperature variance and thermal deformation of a flat plate stainless steel clamped substrate using different laser scanning sequences. During the investigation, it was found that the same direction and different side cladding can better balance the relationship between heat accumulation and heat dissipation on the substrate and molten pool, making the temperature field more uniform and decreasing the deformation of the parts. This study is helpful in improving the quality of the laser cladding parts. Finally, optimized process parameters have been used to further minimize the temperature variance and substrate deformation.
Laser-based additive manufacturing (LBAM) is a group of advanced manufacturing processes used to produce metal components and functionally graded products. Production in LBAM is either limited to the formation of thin or thick coatings on a substrate by laser metal deposition or the production of a fully functional metallic product by selective laser melting. In every case, LBAM fabricated components require optimization for the process parameters to avoid defects, such as porosity, crack holes, thermal deformation, and mechanical strength. As a key link in the laser additive manufacturing (LAM) process, laser scanning path planning is an effective strategy for balancing the temperature field of the formed part, avoiding stress concentration, and preventing deformation and cracking. Efficient, accurate, and reasonable planning of the laser scanning path is of great significance for improving the processing efficiency of the process data, prolonging the life of the laser scanning system, and improving the forming quality of the specimen. Through many studies, it was found that the scanning pattern of the lasers has a significant impact on the mechanical properties and deformations caused by a thermal mismatch during the process. Therefore, it is essential to have in-depth knowledge about path planning in LBAM. Our review mainly focuses on the influence of scanning patterns on deformation, temperature, and mechanical properties in LBAM. Finally, our paper discusses the current study limitations and some future studies in LAM technology.
Laser directed energy deposition (LDED) is one of the most important parts of metal additive manufacturing, which can provide fast building speed, allows for large building volumes, and is suitable for part repair. LDED can manufacture components layer by layer through processes of rapid heating, melting, solidification, and cooling with the laser beam as a heat source. However, deposition quality and repeatability of components produced by LDED are poor because of the complex thermal cycle and processing environment, hindering the spread of this technique. Adaptive control technology (ACT) is consistently considered an effective and potential way to solve the problem. Many studies have focused on LDED and established the relations of process parameters, process signatures, and product qualities, which promote the rapid development of ACT, with the development of monitoring devices and data processing technology. We review and discuss the problems existing in the ACT of LDED.
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