Pengfei Zhao, Xiaobing Zhang, Shuwang Bian, Wenlong Zhang, Zhanyi Cao
To achieve high quality welding of an AZ31 magnesium alloy sheet, butt experiments are conducted using an Nd:YAG pulsed laser welder to weld the AZ31 magnesium alloy (1 mm). The influence of preheating temperature on the microscopic structure and mechanical performance of AZ31 magnesium alloy pulsed laser welding is studied. Experimental results show that with the rising of preheating temperature, the grain size of an equiaxed crystal in the weld center and columnar crystal at the fusion boundary (FB) first decreases and then increases and reaches the minimum values of 18.89 ± 0.45 and 32.09 ± 1.52 μm, respectively, when preheated at 200 °C. The maximum force and tensile strength increase first and decrease and reach the maximum of 2.32 kN and 193.3 MPa, respectively, when the preheating temperature is 300 °C. Above all, the welds with excellent mechanical performance can be obtained at the preheating temperature of 300 °C.
{"title":"Effect of preheating temperature on the microscopic structure and mechanical performance of pulsed laser welding in sheet AZ31 alloy","authors":"Pengfei Zhao, Xiaobing Zhang, Shuwang Bian, Wenlong Zhang, Zhanyi Cao","doi":"10.2351/7.0001214","DOIUrl":"https://doi.org/10.2351/7.0001214","url":null,"abstract":"To achieve high quality welding of an AZ31 magnesium alloy sheet, butt experiments are conducted using an Nd:YAG pulsed laser welder to weld the AZ31 magnesium alloy (1 mm). The influence of preheating temperature on the microscopic structure and mechanical performance of AZ31 magnesium alloy pulsed laser welding is studied. Experimental results show that with the rising of preheating temperature, the grain size of an equiaxed crystal in the weld center and columnar crystal at the fusion boundary (FB) first decreases and then increases and reaches the minimum values of 18.89 ± 0.45 and 32.09 ± 1.52 μm, respectively, when preheated at 200 °C. The maximum force and tensile strength increase first and decrease and reach the maximum of 2.32 kN and 193.3 MPa, respectively, when the preheating temperature is 300 °C. Above all, the welds with excellent mechanical performance can be obtained at the preheating temperature of 300 °C.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140372825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinya Wang, Lanh Trinh, Xiaoming Yu, Matthew J. Berg, Sajed Hosseini-Zavareh, Brice Lacroix, Pingping Chen, Ruqi Chen, Bai Cui, Shuting Lei
The nature of structural changes of nanosecond laser modification inside silicon is investigated. Raman spectroscopy and transmission electron microscopy measurements of cross sections of the modified channels reveal highly localized crystal deformation. Raman spectroscopy measurements prove the existence of amorphous silicon inside nanosecond laser induced modifications, and the percentage of amorphous silicon is calculated based on the Raman spectrum. For the first time, the high-resolution transmission electron microscopy images directly show the appearance of amorphous silicon inside nanosecond laser induced modifications, which corroborates the indirect measurements from Raman spectroscopy. The laser modified channel consists of a small amount of amorphous silicon embedded in a disturbed crystal structure accompanied by strain. This finding may explain the origin of the positive refractive index change associated with the written channels that may serve as optical waveguides.
{"title":"Direct observation and quantification of nanosecond laser induced amorphization inside silicon","authors":"Xinya Wang, Lanh Trinh, Xiaoming Yu, Matthew J. Berg, Sajed Hosseini-Zavareh, Brice Lacroix, Pingping Chen, Ruqi Chen, Bai Cui, Shuting Lei","doi":"10.2351/7.0001305","DOIUrl":"https://doi.org/10.2351/7.0001305","url":null,"abstract":"The nature of structural changes of nanosecond laser modification inside silicon is investigated. Raman spectroscopy and transmission electron microscopy measurements of cross sections of the modified channels reveal highly localized crystal deformation. Raman spectroscopy measurements prove the existence of amorphous silicon inside nanosecond laser induced modifications, and the percentage of amorphous silicon is calculated based on the Raman spectrum. For the first time, the high-resolution transmission electron microscopy images directly show the appearance of amorphous silicon inside nanosecond laser induced modifications, which corroborates the indirect measurements from Raman spectroscopy. The laser modified channel consists of a small amount of amorphous silicon embedded in a disturbed crystal structure accompanied by strain. This finding may explain the origin of the positive refractive index change associated with the written channels that may serve as optical waveguides.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140375827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When predicting welding deformation of the laser-manufactured vehicles and aerospaces, analytical solutions or empirical formulas are not usually accessible in complex problems. Based on the inherent deformation method, a machine learning (ML) approach for predicting welding deformation of welded structures is proposed based on an artificial neural network (ANN). This method is a promising substitute for analytical, empirical, and finite element (FE) solutions due to its accuracy, easy-to-use, efficiency, and universality. First, the outputs of the ANN are determined via dimensionless analysis and comparison of numerical results, which are dimensionally independent. Then, based on the inherent deformation method, the training and validation sets of the ANN are generated through an elastic finite element analysis. At last, the structure of the ANN is determined by analyzing the ANN prediction accuracy with different hidden layers, numbers of neurons, and activation functions. The results show that the ML solutions are in good agreement with the FE results, verifying the effectiveness and generalization ability of the proposed method.
在预测激光制造的车辆和航天器的焊接变形时，对于复杂的问题通常无法获得分析解决方案或经验公式。在固有变形法的基础上，提出了一种基于人工神经网络（ANN）的机器学习（ML）方法，用于预测焊接结构的焊接变形。这种方法因其准确性、易用性、高效性和通用性，有望替代分析法、经验法和有限元（FE）法。首先，通过无量纲分析和数值结果比较确定 ANN 的输出，这些结果在量纲上是独立的。然后，基于固有变形方法，通过弹性有限元分析生成 ANN 的训练集和验证集。最后，通过分析不同隐藏层、神经元数量和激活函数下的 ANN 预测精度，确定了 ANN 的结构。结果表明，ML 解与有限元分析结果十分吻合，验证了所提方法的有效性和泛化能力。
{"title":"Prediction of laser-welded deformation using artificial neural networks","authors":"Zhenfei Guo, Hao Jiang, R. Bai, Zhenkun Lei","doi":"10.2351/7.0001307","DOIUrl":"https://doi.org/10.2351/7.0001307","url":null,"abstract":"When predicting welding deformation of the laser-manufactured vehicles and aerospaces, analytical solutions or empirical formulas are not usually accessible in complex problems. Based on the inherent deformation method, a machine learning (ML) approach for predicting welding deformation of welded structures is proposed based on an artificial neural network (ANN). This method is a promising substitute for analytical, empirical, and finite element (FE) solutions due to its accuracy, easy-to-use, efficiency, and universality. First, the outputs of the ANN are determined via dimensionless analysis and comparison of numerical results, which are dimensionally independent. Then, based on the inherent deformation method, the training and validation sets of the ANN are generated through an elastic finite element analysis. At last, the structure of the ANN is determined by analyzing the ANN prediction accuracy with different hidden layers, numbers of neurons, and activation functions. The results show that the ML solutions are in good agreement with the FE results, verifying the effectiveness and generalization ability of the proposed method.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140378486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Sugrim, Gunjan Kulkarni, Yahya Bougdid, Kevin Heylman, Ranganathan Kumar, Aravinda Kar, Kalpathy Sundaram
Semi-insulating (SI) 4H-polytype of silicon carbide (SiC) is a highly desirable wide bandgap semiconductor material for various applications in challenging environments owing to its exceptional characteristics such as high melting point, remarkable thermal conductivity, strong breakdown field, and excellent resistance to oxidation. This study investigates the critical laser processing parameters to operate a pulsed UV 355 nm laser to dope high-purity (HP) SI 4H-SiC substrates with boron. The doping process parameters are examined and simulated for this UV laser doping system using a liquid precursor of boron. Boron atoms create a dopant energy level of 0.3eV in the doped HP 4H-SiC substrates. Diffusion of boron atoms into 4H-SiC substrates modifies the hole density at 0.3eV energy level, and causing a variation in the dynamic refraction index, and absorption index. Consequently, the optical properties of boron doped samples, namely, transmittance, reflectance, and absorbance, can be modified. The current simulation reported in this study explains the motivation of UV optical doping strategy to dope SiC substrates. A beam homogenizer was used to control the laser spot used to generate doping process. The advantage of the beam homogenizer is demonstrated by producing flat-top beams with uniform intensity over a certain area defined by the focusing lens choice. A simple theoretical model is used to select the laser processing parameters for doping SiC substrates. These modeled parameters are used to determine the efficient laser processing parameters for our doping experiments.
半绝缘（SI）4H-聚类碳化硅（SiC）具有熔点高、热导率高、击穿场强和抗氧化性强等优异特性，是一种非常理想的宽带隙半导体材料，可用于各种具有挑战性的环境中。本研究探讨了使用脉冲紫外 355 纳米激光器在高纯度 (HP) SI 4H-SiC 基底上掺杂硼的关键激光加工参数。使用液态硼前驱体对这种紫外激光掺杂系统的掺杂工艺参数进行了研究和模拟。硼原子在掺杂的 HP 4H-SiC 基底中产生了 0.3eV 的掺杂能级。硼原子扩散到 4H-SiC 衬底中，改变了 0.3eV 能级的空穴密度，并导致动态折射率和吸收率的变化。因此，掺硼样品的光学特性，即透射率、反射率和吸收率都会发生变化。本研究报告中的模拟解释了采用紫外光掺杂策略掺杂碳化硅基底的动机。使用光束匀浆器来控制激光光斑，以产生掺杂过程。通过在聚焦透镜选择确定的一定区域内产生强度均匀的平顶光束，证明了光束匀浆器的优势。一个简单的理论模型用于选择掺杂碳化硅衬底的激光加工参数。这些建模参数用于确定我们掺杂实验的高效激光加工参数。
{"title":"Numerical investigation of laser doping parameters for semi-insulating 4H-SiC substrate","authors":"C. Sugrim, Gunjan Kulkarni, Yahya Bougdid, Kevin Heylman, Ranganathan Kumar, Aravinda Kar, Kalpathy Sundaram","doi":"10.2351/7.0001158","DOIUrl":"https://doi.org/10.2351/7.0001158","url":null,"abstract":"Semi-insulating (SI) 4H-polytype of silicon carbide (SiC) is a highly desirable wide bandgap semiconductor material for various applications in challenging environments owing to its exceptional characteristics such as high melting point, remarkable thermal conductivity, strong breakdown field, and excellent resistance to oxidation. This study investigates the critical laser processing parameters to operate a pulsed UV 355 nm laser to dope high-purity (HP) SI 4H-SiC substrates with boron. The doping process parameters are examined and simulated for this UV laser doping system using a liquid precursor of boron. Boron atoms create a dopant energy level of 0.3eV in the doped HP 4H-SiC substrates. Diffusion of boron atoms into 4H-SiC substrates modifies the hole density at 0.3eV energy level, and causing a variation in the dynamic refraction index, and absorption index. Consequently, the optical properties of boron doped samples, namely, transmittance, reflectance, and absorbance, can be modified. The current simulation reported in this study explains the motivation of UV optical doping strategy to dope SiC substrates. A beam homogenizer was used to control the laser spot used to generate doping process. The advantage of the beam homogenizer is demonstrated by producing flat-top beams with uniform intensity over a certain area defined by the focusing lens choice. A simple theoretical model is used to select the laser processing parameters for doping SiC substrates. These modeled parameters are used to determine the efficient laser processing parameters for our doping experiments.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140380657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xueqian Qin, Yaowu Zhao, Yao Wang, Junjie Zeng, Liao Zhou, Jinguo Ge, Qingyuan Liu, Jia Zhou, Yuhong Long
In this paper, the process parameters of pulsed laser welding of Al–Cu are studied using response surface methodology (RSM) and grey relation analysis (GRA) to propose optimal directions for lap-shear strength of the joints. A single-factor experiment was conducted to find the suitable process parameter windows. The RSM models were established and analyzed with laser power, welding speed, pulse width, and frequency as inputs and joint lap shear, interfacial weld width, and weld-penetration-depth as outputs. With the use of GRA of interfacial weld width and weld penetration depth with the lap-shear force of joints, the improved direction for the lap-shear force of joints can be proposed.
{"title":"Optimization and GRA prediction of Al–Cu pulsed laser welding process based on RSM","authors":"Xueqian Qin, Yaowu Zhao, Yao Wang, Junjie Zeng, Liao Zhou, Jinguo Ge, Qingyuan Liu, Jia Zhou, Yuhong Long","doi":"10.2351/7.0001249","DOIUrl":"https://doi.org/10.2351/7.0001249","url":null,"abstract":"In this paper, the process parameters of pulsed laser welding of Al–Cu are studied using response surface methodology (RSM) and grey relation analysis (GRA) to propose optimal directions for lap-shear strength of the joints. A single-factor experiment was conducted to find the suitable process parameter windows. The RSM models were established and analyzed with laser power, welding speed, pulse width, and frequency as inputs and joint lap shear, interfacial weld width, and weld-penetration-depth as outputs. With the use of GRA of interfacial weld width and weld penetration depth with the lap-shear force of joints, the improved direction for the lap-shear force of joints can be proposed.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingjun Lin, Panyang Dai, Changjin Che, Xiaomei Lin, Yao Li, Jiangfei Yang, Yutao Huang, Yongkang Ren, Xin Zhen, Xingyue Yang
In the recycling of scrap metal, the establishment of the classification database of recyclables has the advantages of fast classification speed and high analysis accuracy. However, the classification and recycling of unknown samples become highly significant due to the extensive variety of standard metal samples and the challenges in obtaining them. In this study, a method for multi-element classification of automotive scrap metals in general environmental conditions was achieved by utilizing laser-induced breakdown spectroscopy (LIBS) and two-step clustering algorithm (K-means, hierarchical clustering). The two unsupervised learning algorithms were employed to cluster the LIBS spectral data of 60 automotive scrap metal samples rapidly and hierarchically. Three rare metal elements and three elements for distinguishing metal categories were selected to meet the recycling requirements. After applying the multiplicative scatter correction to the spectral data for calibration, the initial clustering clusters were determined using the Davies–Bouldin index, Calinski–Harabasz index, and silhouette coefficient. Then, the Kruskal–Wallis test was conducted on each cluster to check the significance. The clusters that failed the test were split and reclustered until all clusters met the significance criterion (α=0.05). The accuracy of the proposed method for classifying the collected automotive scrap metals reached 97.6%. This indicates the great potential of this method in the field of automotive scrap metal classification.
{"title":"Research on automotive scrap metal classification method using laser-induced breakdown spectroscopy and two-step clustering algorithm","authors":"Jingjun Lin, Panyang Dai, Changjin Che, Xiaomei Lin, Yao Li, Jiangfei Yang, Yutao Huang, Yongkang Ren, Xin Zhen, Xingyue Yang","doi":"10.2351/7.0001289","DOIUrl":"https://doi.org/10.2351/7.0001289","url":null,"abstract":"In the recycling of scrap metal, the establishment of the classification database of recyclables has the advantages of fast classification speed and high analysis accuracy. However, the classification and recycling of unknown samples become highly significant due to the extensive variety of standard metal samples and the challenges in obtaining them. In this study, a method for multi-element classification of automotive scrap metals in general environmental conditions was achieved by utilizing laser-induced breakdown spectroscopy (LIBS) and two-step clustering algorithm (K-means, hierarchical clustering). The two unsupervised learning algorithms were employed to cluster the LIBS spectral data of 60 automotive scrap metal samples rapidly and hierarchically. Three rare metal elements and three elements for distinguishing metal categories were selected to meet the recycling requirements. After applying the multiplicative scatter correction to the spectral data for calibration, the initial clustering clusters were determined using the Davies–Bouldin index, Calinski–Harabasz index, and silhouette coefficient. Then, the Kruskal–Wallis test was conducted on each cluster to check the significance. The clusters that failed the test were split and reclustered until all clusters met the significance criterion (α=0.05). The accuracy of the proposed method for classifying the collected automotive scrap metals reached 97.6%. This indicates the great potential of this method in the field of automotive scrap metal classification.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140383206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bolong Zhou, Qiang Jia, Yishu Wang, Dan Li, Hongqiang Zhang, Huan Hu, Limin Ma, Guisheng Zou, Fu Guo
Ag-Cu nanoparticles, integrating the advantages of Ag and Cu, are promising materials for power electronic packaging. In this work, a novel dual-beam pulsed laser deposition method was proposed to prepare an Ag-Cu nanoparticle film with various component ratios and used for die attach at low temperatures. The as-deposited Ag-Cu nanoparticle film was mainly composed of Ag-Cu solid solution, Ag element, and Cu element, and most of the nanoparticles were in the alloying state. The Ag-Cu sintered joint presented a dense microstructure with 10.8% porosity, and the shear strength of Ag-Cu sintered joints could reach 60 MPa at 250 °C. The sintered joint porosity increased as more Cu were added in the Ag-Cu nanoparticle film, resulting in a decrease in the interfacial connection ratio. The fracture mode of sintered joints gradually changed from the sintered layer to the mixed sintered layer and interface fracture. The dual-beam pulsed laser deposition method could guide in designing the component ratios of bimetallic nanoparticles.
{"title":"Preparation of Ag-Cu nanoparticle film using a dual-beam pulsed laser deposition for power electronic packaging","authors":"Bolong Zhou, Qiang Jia, Yishu Wang, Dan Li, Hongqiang Zhang, Huan Hu, Limin Ma, Guisheng Zou, Fu Guo","doi":"10.2351/7.0001321","DOIUrl":"https://doi.org/10.2351/7.0001321","url":null,"abstract":"Ag-Cu nanoparticles, integrating the advantages of Ag and Cu, are promising materials for power electronic packaging. In this work, a novel dual-beam pulsed laser deposition method was proposed to prepare an Ag-Cu nanoparticle film with various component ratios and used for die attach at low temperatures. The as-deposited Ag-Cu nanoparticle film was mainly composed of Ag-Cu solid solution, Ag element, and Cu element, and most of the nanoparticles were in the alloying state. The Ag-Cu sintered joint presented a dense microstructure with 10.8% porosity, and the shear strength of Ag-Cu sintered joints could reach 60 MPa at 250 °C. The sintered joint porosity increased as more Cu were added in the Ag-Cu nanoparticle film, resulting in a decrease in the interfacial connection ratio. The fracture mode of sintered joints gradually changed from the sintered layer to the mixed sintered layer and interface fracture. The dual-beam pulsed laser deposition method could guide in designing the component ratios of bimetallic nanoparticles.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140382055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oscillating beam was used for laser welding of TC11 titanium alloys. The porosity, microstructure, and mechanical properties of welds with different parameters were studied. It was found that increasing the oscillation frequency could effectively suppress porosity. When the oscillation amplitude was less than or equal to 1 mm, the laser power was about 3 kW, and the welding speed was less than 15 mm/s, porosity could be effectively suppressed. Both oscillation frequency and amplitude could increase the number of α′-phase. The oscillation frequency promoted the cross distribution of α′-phase and α″-phase in the columnar crystal. The oscillation amplitude promotes the uniform distribution of α′-phase in the columnar crystal. Increasing the oscillation frequency and the oscillation amplitude was beneficial to increase the tensile strength. In the case of low defect rates, the tensile strength of the weld could reach more than 90% of the base metal, and the maximum elongation was 7.5%.
{"title":"Effects of beam oscillation on porosity and microstructure of laser welded TC11 titanium alloy","authors":"Can Luo, Wei Peng, Chen Zhang","doi":"10.2351/7.0001262","DOIUrl":"https://doi.org/10.2351/7.0001262","url":null,"abstract":"Oscillating beam was used for laser welding of TC11 titanium alloys. The porosity, microstructure, and mechanical properties of welds with different parameters were studied. It was found that increasing the oscillation frequency could effectively suppress porosity. When the oscillation amplitude was less than or equal to 1 mm, the laser power was about 3 kW, and the welding speed was less than 15 mm/s, porosity could be effectively suppressed. Both oscillation frequency and amplitude could increase the number of α′-phase. The oscillation frequency promoted the cross distribution of α′-phase and α″-phase in the columnar crystal. The oscillation amplitude promotes the uniform distribution of α′-phase in the columnar crystal. Increasing the oscillation frequency and the oscillation amplitude was beneficial to increase the tensile strength. In the case of low defect rates, the tensile strength of the weld could reach more than 90% of the base metal, and the maximum elongation was 7.5%.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140225083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Heilmeier, Michael K. Kick, Sophie Grabmann, Tatek Muschol, Franz Schlicht, Felix von Hundelshausen, Hans-Georg von Ribbeck, T. Weiss, M. F. Zaeh
The mobility sector is considered a major contributor to global greenhouse gas emissions and air pollution. As a result, many countries have initiated the transition from fossil fuel-powered to electrified powertrains. This transformation of the powertrain concept will lead to a rapid increase in the production of electric vehicles and, therefore, to a high demand for so-called traction batteries. As a production step of the traction batteries, a connection between the cell connector and the terminal of the battery cell has to be manufactured. For this purpose, laser beam welding is a reliable and efficient joining technique. In order to ensure continuous quality of the welding process during production and to detect defects in real time, reliable process monitoring is required. In this study, spectral and acoustic emissions during laser beam welding were recorded using a laser welding monitor and an optical microphone. For determining possible correlations between the signals and weld defects, various failure cases were generated by the systematic placement of disturbance elements. These elements included a contaminated surface, a gap between the cell connector and the battery cell, and a misalignment of the cell connector. Based on the recorded signals, statistical metrics were calculated. Finally, weld seams with and without defects were compared to assess the capability of both sensor systems for detecting the weld defects.
{"title":"Inline failure detection in laser beam welding of battery cells: Acoustic and spectral emission analysis for quality monitoring","authors":"Johannes Heilmeier, Michael K. Kick, Sophie Grabmann, Tatek Muschol, Franz Schlicht, Felix von Hundelshausen, Hans-Georg von Ribbeck, T. Weiss, M. F. Zaeh","doi":"10.2351/7.0001216","DOIUrl":"https://doi.org/10.2351/7.0001216","url":null,"abstract":"The mobility sector is considered a major contributor to global greenhouse gas emissions and air pollution. As a result, many countries have initiated the transition from fossil fuel-powered to electrified powertrains. This transformation of the powertrain concept will lead to a rapid increase in the production of electric vehicles and, therefore, to a high demand for so-called traction batteries. As a production step of the traction batteries, a connection between the cell connector and the terminal of the battery cell has to be manufactured. For this purpose, laser beam welding is a reliable and efficient joining technique. In order to ensure continuous quality of the welding process during production and to detect defects in real time, reliable process monitoring is required. In this study, spectral and acoustic emissions during laser beam welding were recorded using a laser welding monitor and an optical microphone. For determining possible correlations between the signals and weld defects, various failure cases were generated by the systematic placement of disturbance elements. These elements included a contaminated surface, a gap between the cell connector and the battery cell, and a misalignment of the cell connector. Based on the recorded signals, statistical metrics were calculated. Finally, weld seams with and without defects were compared to assess the capability of both sensor systems for detecting the weld defects.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140392197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chad B. Durrant, G. Brennecka, J. Wimpenny, D. Weisz, Raymond Mariella
Traditional dissolution of geologic samples often requires a significant time investment. Here, we present an alternative method for the dissolution of geologic materials using laser-driven hydrothermal processing (LDHP). LDHP uses laser energy directed onto a submerged sample, which increases the temperature and pressure at the liquid–sample interface and drives the hydrothermal dissolution coupled with photomechanical spallation, an ablative process. This uses focused 527 nm laser energy at 40 W average power, 1 kHz pulse repetition rate, and 115 ns pulse duration. When LDHP is performed on basalt geostandards (BCR-2 and BHVO-2) using the conditions outlined, we show that LDHP does not produce significant elemental fractionation and, thus, can be considered an alternative processing method to traditional mechanical crushing and acid digestion. Additionally, it is possible using LDHP to utilize the spatially confined beam to target and selectively isolate individual phases in a rock, potentially alleviating the need for mechanical separation of inclusions that are difficult to physically isolate. Furthermore, using this outlined method of LDHP, we demonstrate full dissolution of 120 mg of obsidian in 85 minu, meaning that LDHP is a potentially very useful method when sample processing is time sensitive.
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