Advances in Manufacturing

Feasibility analysis and process characteristics of selective laser ablation assisted milling Inconel 718

Bao-Yu Zhang, Yu-Ning Zeng, Xue-Qin Pang, Song-Qing Li, Xiao Liu, Wen-Jun Deng

2022, 10(4): 495-519. doi:10.1007/s40436-021-00384-9

摘要 ( 2310 )

PDF (493KB) ( 134 )

参考文献 | 相关文章 | 多维度评价

Laser-assisted machining (LAM), as one of the most efficient ways, has been employed to improve the machinability of nickel-based superalloys. However, the conventional LAM process usually used high power laser with large spot size, easily leading to high processing costs and overheating of bulk materials. In this paper, a new approach of selective laser ablation assisted milling (SLA-Mill) process for nickel-based superalloys was proposed, in which low power laser with small spot size was used to selectively ablate the uncut surface in front of the cutting tool, resulting in plentiful surface defects emerging. Such defects would significantly weaken the mechanical strength of difficult-to-cut materials, which was different from the thermal "softening" principle of conventional LAM. Thus, the laser ablation effect with low power and small spot size was first studied. The relationship between process parameters (e.g., laser power, cutting speed and cutting depth) and process characteristics of SLA-Mill (e.g., chip morphology, tool wear and surface integrity) was systematically discussed. Moreover, the chip formation mechanism in the SLA-Mill process was indepth analyzed. Results show that the SLA-Mill process is an effective approach for enhancing the machinability of nickel-based superalloys. The resultant cutting force has a reduction of about 30% at laser power of 60 W, cutting speed of 90 m/min, and cutting depth of 0.1 mm. Furthermore, the chip formation, tool wear, and surface integrity have improved significantly. In general, this paper provides a new route for the application of LAM technology.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-021-00384-9

Influences of processing parameters and heat treatment on microstructure and mechanical behavior of Ti-6Al-4V fabricated using selective laser melting

Qi-Dong Sun, Jie Sun, Kai Guo, Saad Waqar, Jiang-Wei Liu, Lei-Shuo Wang

2022, 10(4): 520-540. doi:10.1007/s40436-022-00389-y

摘要 ( 2303 )

PDF (500KB) ( 167 )

参考文献 | 相关文章 | 多维度评价

Selective laser melting (SLM) has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features. Therefore, this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM. The influences of various process parameters on the relative density, tensile properties, impact toughness, and hardness of Ti-6Al-4V alloy parts were studied. By employing parameter optimization, a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM. A relative density of 99.45%, a tensile strength of 1 188 MPa, and an elongation to failure of 9.5% were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters. The effects of annealing and solution aging heat treatment on the mechanical properties, phase composition, and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied. The ductility of the heat-treated Ti-6Al-4V alloy was improved. By applying a heat treatment at 850 ℃ for 2 h, followed by furnace cooling, the elongation to failure and impact toughness were found to be increased from 9.5% to 12.5%, and from 24.13 J/cm² to 47.51 J/cm², respectively.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00389-y

Effect of stepover and torch tilting angle on a repair process using WAAM

Francesco Baffa, Giuseppe Venturini, Gianni Campatelli, Emanuele Galvanetto

2022, 10(4): 541-555. doi:10.1007/s40436-022-00393-2

摘要 ( 2290 )

PDF (494KB) ( 187 )

参考文献 | 相关文章 | 多维度评价

To sustain the transition to a greener economy and greener manufacturing, it is necessary to develop new approaches and technologies to repair metal components; this will result in a drastic reduction in energy and material usage. In this study, wire arc additive manufacturing (WAAM) was used to deposit a layer of new material on an existing surface, with the objective of finding the optimal configuration that maximized the layer quality and material efficiency. The parameters considered are the stepover among the deposited beads and the inclination of the torch with respect to the repaired surfaces. The inclination angle is crucial when repairing complex surfaces, like those of a mold, owing to accessibility issues, the torch cannot be maintained orthogonal to the surfaces along the entire toolpath. Different configurations were tested in order to assess the quality of the materials in terms of the presence of material voids, depth of penetration, and the heat affected zone (HAZ) and to understand the effects of these variables on the material efficiency and thickness of the repairing layer. It should be noted that by adopting deposition parameters set to have a low heat input, the use of a tilting angle has beneficial effects on the quality of the deposited layer and the process efficiency. Metallurgical and geometrical measurements were carried out to assess the effect of these two variables depositing a layer of plain carbon steel.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00393-2

High-accuracy calibration for multi-laser powder bed fusion via in situ detection and parameter identification

Qi Zhong, Xiao-Yong Tian, Xiao-Kang Huang, Zhi-Qiang Tong, Yi Cao, Di-Chen Li

2022, 10(4): 556-570. doi:10.1007/s40436-022-00392-3

摘要 ( 2412 )

PDF (496KB) ( 282 )

参考文献 | 相关文章 | 多维度评价

Multi-laser powder bed fusion (ML-PBF) adopts multiple laser-scanner systems to increase the build envelope and build speed, but its calibration is an iterative and time-consuming process. In particular, multiple large-scale scan fields have a complex distortion in the overlap area, challenging the calibration process. In this study, owing to the enormous workload and alignment problems in the calibration of multiple scan fields, a novel calibration system is designed in this study to realize in situ auto-detection of numerous laser spots in the build chamber to ensure high efficiency and accuracy. Moreover, because the detectable area could not cover the entire build area and the detection data still contained errors, a virtual laser-scanner system was established by identifying the assembly defects and galvo nonlinearities of the ML-PBF system from the detection data, which served as the system's controller to improve calibration accuracy. The multi-field alignment error was less than 0.012%, which could avoid the intersection and separation of scan paths in multi-laser scanning and therefore meet the requirements for high-precision ML-PBF. Finally, the reliability of the method was verified theoretically using principal component analysis.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00392-3

Real-time monitoring of raster temperature distribution and width anomalies in fused filament fabrication process

Feng Li, Zhong-Hua Yu, Hao Li, Zhen-Sheng Yang, Qing-Shun Kong, Jie Tang

2022, 10(4): 571-582. doi:10.1007/s40436-021-00385-8

摘要 ( 2324 )

PDF (493KB) ( 105 )

参考文献 | 相关文章 | 多维度评价

The aim of this study is to monitor the raster temperature distribution and width anomalies in a fused filament fabrication (FFF) process by an infrared (IR) array sensor. To achieve this goal, two experiments were conducted on a desktop FFF machine. For the first experiment, three normal samples with different raster widths were fabricated, and thermal images of the newly deposited rasters were collected during the process. To process the low-resolution images, a segmentation-based image processing method was proposed. The temperature distributions along the horizontal direction of the raster section and along the raster length were obtained. The temperature features that could indicate the raster widths were extracted and then fed to recognition models for training and testing. The classification performance of the models were evaluated based on the F-score. The models with high F1-scores could be used to recognise width anomalies online. For the second experiment, an abnormal sample with raster width anomalies was fabricated. The temperature features were extracted from the collected experimental data. The obtained features were then fed to the built and evaluated models to recognise the width anomalies online. The effectiveness of the monitoring method was validated by comparing the recognition results with the actual optical images. The support vector machine (SVM) and k-nearest neighbour (KNN) were adopted to build the recognition models. The F1-score and online recognition results of the models were compared. The comparison study shows that SVM is more suitable for our situation than KNN. A method for monitoring the temperature distribution and width anomalies of the FFF raster is provided in this paper. To the best of the authors' knowledge, this is the first study to explore the actual temperature distribution along the horizontal direction of the raster section, and the first study to monitor the width anomalies of the raster in the FFF process.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-021-00385-8

Electrical arc contour cutting based on a compound arc breaking mechanism

Guo-Jian He, Lin Gu, Ying-Mou Zhu, Ji-Peng Chen, Wan-Sheng Zhao, K. P. Rajurkar

2022, 10(4): 583-595. doi:10.1007/s40436-022-00406-0

摘要 ( 2411 )

PDF (544KB) ( 91 )

参考文献 | 相关文章 | 多维度评价

Electrical arc contour cutting (EACC) is a novel high-efficiency material cutting process that applies arc plasma to perform efficient and economical contour cutting of difficult-to-cut materials. Compared to conventional electrical arc machining (EAM), this process can remove the allowance of open structures and plates in bulk mode, rather than entirely in the form of debris. Compared with existing contour cutting methods, EACC possesses the advantages of high cutting efficiency and a deep cutting depth. Particularly, a compound arc breaking mechanism (CABM), which integrates hydrodynamic force and mechanical motion, has been applied to control the discharge arc column in EACC, while also strengthening the debris expelling effect in the narrow discharge gap. The CABM implementation conditions were studied, based on arc column distortion images captured by a high-speed camera and simulation results of the flow field and debris distribution. A set of machining experiments was designed and conducted to optimize the performance of the proposed process. Finally, a SiC_p/Al metal matrix composite (MMC) space station workpiece was machined to verify the feasibility and efficiency of this process.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00406-0

Microstructures and properties evolution of Al-Zn-Mg-Cu alloy under electrical pulse assisted creep aging

Tian-Jun Bian, Heng Li, Chao Lei, Chang-Hui Wu, Li-Wen Zhang

2022, 10(4): 596-609. doi:10.1007/s40436-022-00404-2

摘要 ( 2413 )

PDF (556KB) ( 120 )

参考文献 | 相关文章 | 多维度评价

Creep aging (CA) is a promising forming technology for integral panels with complex structures. However, how to balance excellent corrosion resistance and strength is still a challenge for CA parts. By synchronously applying electrical pulse (300 Hz, 15 A/mm²) in the middle of steady-state CA of Al-Zn-Mg-Cu alloy, the electrically assisted CA (ECA) is proposed to induce retrogression rapidly for realizing a three-step aging (retrogression and re-aging, RRA) in CA to tailor the needed properties balance. It is compared with conventional CA with one-step aging (peak aging, T6 or over aging, T7), two-step aging (over aging, T73) and RRA in hardness, intergranular corrosion and microstructures. For the ECA of pre-aging and re-aging for 20 h plus electropulsing for 10 min, the hardness is 10.5%, 20.5% and 18.9% higher than those of CA with T6, T7 and T73 processes, respectively, while the corrosion resistance is higher than T6 process and lower than T7 and T73 processes. Although the hardness and corrosion resistance are comparable to those of the CA with the RRA process, ECA takes one hour less due to the accelerated effect of the electropulsing and is not limited by the thick plates. The improved comprehensive performance of the ECA sample is due to both fine intragranular precipitates η′ and large discontinuous grain boundary precipitates η.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00404-2

The development of a high-performance Ni-superalloy additively manufactured heat pipe

Sheng Li, Khamis Essa, James Carr, States Chiwanga, Andrew Norton, Moataz M. Attallah

2022, 10(4): 610-624. doi:10.1007/s40436-022-00407-z

摘要 ( 2402 )

PDF (316KB) ( 171 )

参考文献 | 相关文章 | 多维度评价

Additively manufacturing (AM) has been used to manufacture fine structures with structured/engineered porosity in heat management devices. In this study, laser powder bed fusion (LPBF) was used to manufacture a high-performance Ni-superalloy heat pipe, through tailoring LPBF process parameters to fabricate thin wall and micro-channel. By using novel laser scanning strategies, wick structure heat pipes with maximised surface-area-to-volume ratio, fine features size around 100 μm, and controlled porosity were successfully fabricated. Microscopy and X-ray microtomography (micro-CT) were used to investigate the 3D structure of the void space within the pipe. Wick test results showed that most of the heat pipes made by LPBF had better performance than the conventionally manufactured pipes. This study also investigated the influences of the process parameters on the porosity volume fraction and the feature size. The results showed that LPBF process could fabricate thin structure due to the change of melt pool contact angle. The relationship between process parameters and bead size reported in this study could help design and manufacture heat pipe with complex fine structure.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00407-z

当期目录