Special Issue "Recent Advances in Joining and Welding Technology Coping with New Material Combination"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Applied Industrial Technologies".

Deadline for manuscript submissions: closed (31 October 2020).

Special Issue Editor

Dr. Cheolhee Kim
Website
Guest Editor
Joining R&D Group, Korea Institute of Industrial Technology (KITECH), 156, Gaetbeol-ro, Yeonsu-Gu, Incheon 21999, Korea
Interests: welding processes; arc physics; laser welding; friction stir welding
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Special Issue Information

Dear Colleagues,

Materials in industrial applications have rapidly changed in the last two decades. As conventional mild steel is being replaced with high strength steels, nonferrous alloys, polymers, and composites, new joining and welding technologies have been required to cope with new material combinations. In order to ensure excellent productivity and quality in joining unexplored material combinations, welding researchers are continuously developing laser welding, friction stir welding, ultrasonic welding, adhesive bonding, and mechanical joining processes. Even for traditional arc welding and resistance spot welding processes, new welding materials, high production processes, and smart equipment are being developed.

This Special Issue covers the original review and contributed articles on recent advances in innovative welding and joining technologies for nontraditional material combinations. Topics include new processes, filler materials, monitoring and control systems, assessments, and applications.

Dr. Cheolhee Kim
Guest Editor

Manuscript Submission Information

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Keywords

  • welding
  • joining
  • high strength steel
  • nonferrous alloy
  • polymer
  • composite

Published Papers (5 papers)

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Research

Open AccessArticle
A Convenient Unified Model to Display the Mobile Keyhole-Mode Arc Welding Process
Appl. Sci. 2020, 10(22), 7955; https://doi.org/10.3390/app10227955 - 10 Nov 2020
Abstract
Keyhole-mode plasma arc welding (PAW) has a good prospect in the manufacturing industry. Unified models of plasma arc and workpiece help to reveal the physical mechanism in PAW for a better application. Previous unified models either deal with a constant keyhole situation or [...] Read more.
Keyhole-mode plasma arc welding (PAW) has a good prospect in the manufacturing industry. Unified models of plasma arc and workpiece help to reveal the physical mechanism in PAW for a better application. Previous unified models either deal with a constant keyhole situation or take too much computational time to display the dynamic keyhole process with a two-phase flow method. In view of the convenience for industrial application as well as good accuracy, a convenient unified model was developed to describe the mobile keyhole-mode PAW. With a simplified technique, the multiphase heat and force effect between plasma arc and workpiece was turned into a single-phase problem at each individual domain. Thus, it takes less computational time than previous unified models. The temperature field and weld pool during the mobile keyhole-mode PAW process were revealed, the arc flow and pool flow were displayed and the electric potential was predicted. The experiment was conducted on a stainless-steel plate, and the weld pool image and the measured arc pressure agree well with the calculated result. The calculated electric potential drop also coincides with the experiment. The model provides a convenient and accurate method to display the mobile keyhole-mode arc welding process. Full article
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Open AccessArticle
Parametric Investigation of Effect of Abnormal Process Conditions on Self-Piercing Riveting
Appl. Sci. 2020, 10(7), 2520; https://doi.org/10.3390/app10072520 - 06 Apr 2020
Abstract
Self-piercing riveting (SPR) is one of the mechanical joining processes, and its application to Al/Fe dissimilar materials combination, which is hard to weld, is expanding in the automotive industry. The main process parameters in SPR are types of rivet and die, setting force, [...] Read more.
Self-piercing riveting (SPR) is one of the mechanical joining processes, and its application to Al/Fe dissimilar materials combination, which is hard to weld, is expanding in the automotive industry. The main process parameters in SPR are types of rivet and die, setting force, and rivet setting speed. Previously, the relationship between the main process parameters and output parameters such as cross-sectional characteristics and joint strength has been studied to optimize the SPR process. In practical applications, there are unexpected and abnormal process conditions such as poor fit-up, angular misalignment, edge offset distance, and inaccurate setting and pre-clamping forces, and their effects on the joining quality have not been discussed. In this study, parametric investigation was performed using an experimental design on SPR joints for 1 mm-thick high strength steel (590 DP) and 2 mm-thick Al alloy (Al5052-H32). The main effect of each level of the abnormal process parameters on the output parameters was statistically investigated, and the analysis of variance was performed for each abnormal process parameter. In the range of abnormal process conditions applied, the set force was the most significant factor affecting the output parameters, and the effect of pre-clamping force on the output parameters was the least significant. Full article
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Open AccessArticle
A High-Performance Deep Learning Algorithm for the Automated Optical Inspection of Laser Welding
Appl. Sci. 2020, 10(3), 933; https://doi.org/10.3390/app10030933 - 31 Jan 2020
Cited by 5
Abstract
The battery industry has been growing fast because of strong demand from electric vehicle and power storage applications.Laser welding is a key process in battery manufacturing. To control the production quality, the industry has a great desire for defect inspection of automated laser [...] Read more.
The battery industry has been growing fast because of strong demand from electric vehicle and power storage applications.Laser welding is a key process in battery manufacturing. To control the production quality, the industry has a great desire for defect inspection of automated laser welding. Recently, Convolutional Neural Networks (CNNs) have been applied with great success for detection, recognition, and classification. In this paper, using transfer learning theory and pre-training approach in Visual Geometry Group (VGG) model, we proposed the optimized VGG model to improve the efficiency of defect classification. Our model was applied on an industrial computer with images taken from a battery manufacturing production line and achieved a testing accuracy of 99.87%. The main contributions of this study are as follows: (1) Proved that the optimized VGG model, which was trained on a large image database, can be used for the defect classification of laser welding. (2) Demonstrated that the pre-trained VGG model has small model size, lower fault positive rate, shorter training time, and prediction time; so, it is more suitable for quality inspection in an industrial environment. Additionally, we visualized the convolutional layer and max-pooling layer to make it easy to view and optimize the model. Full article
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Open AccessArticle
Effect of Different Bonding Materials on Flip-Chip LED Filament Properties
Appl. Sci. 2020, 10(1), 47; https://doi.org/10.3390/app10010047 - 19 Dec 2019
Abstract
This article researches the effect of Sn-based solder alloys on flip-chip light-emitting diode LED (FC-LED) filament properties. SEM images, shearing force, steady-state voltage, blue light luminous flux, and junction temperature were examined to demonstrate the difference between two types of FC-LED filaments welded [...] Read more.
This article researches the effect of Sn-based solder alloys on flip-chip light-emitting diode LED (FC-LED) filament properties. SEM images, shearing force, steady-state voltage, blue light luminous flux, and junction temperature were examined to demonstrate the difference between two types of FC-LED filaments welded with two solders. The microstructure surface of Sn90Sb10 filament solder joints was smoother and had fewer voids and cracks compared with that of SAC0307 filament solder joints, which indicates that the Sn90Sb10 filaments had a higher shearing force than the SAC0307 filaments; moreover, the average shearing force was beyond 200 gf (standard shearing force). The steady-state voltage and junction temperature of the Sn90Sb10 solder-welded FC-LED filament were lower, and the Sn90Sb10 filament had a relatively higher blue light luminous flux. If high reliability of the solder joints and better photoelectric properties of the filaments are required, this Sn90Sb10 solder is the best bonding material for FC-LED filament welding. Full article
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Open AccessArticle
Pre-Inscribed Laser Surface Pattering for Increased Joining Strength in Laser Fusion Bonding of CFRP and Zinc-Coated Steel
Appl. Sci. 2019, 9(21), 4640; https://doi.org/10.3390/app9214640 - 31 Oct 2019
Cited by 1
Abstract
In this study, we present improved fusion-bonding strength results between carbon fiber-reinforced polyetheretherketone (CFR-PEEK) and zinc-coated steel through the introduction of pre-inscribed laser surface patterns. Optimized laser welding parameters, including laser power, focal position, pitch, number of passes, and clamping pressure, are presented [...] Read more.
In this study, we present improved fusion-bonding strength results between carbon fiber-reinforced polyetheretherketone (CFR-PEEK) and zinc-coated steel through the introduction of pre-inscribed laser surface patterns. Optimized laser welding parameters, including laser power, focal position, pitch, number of passes, and clamping pressure, are presented along with parameters for producing the rectangular laser patterns. It was found that for the optimized parameters, the tensile shear strength of the welded samples is improved by as much as 100% when pre-inscribed laser patterns are present. Detailed SEM images of the fractured fusion welded joint samples after the tensile shear test are presented for analysis. The tight bonding between the polymer matrix and the zinc-coated steel inside the formed grooves is found to be the main reason behind the increased tensile shear strength. A comparison of the tensile shear loads for various joining methods is also presented and discussed. Full article
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