Research

12 pages, 36213 KiB

Open AccessArticle

by Mariia Rashkovets, Maria Emanuela Palmieri, Nicola Contuzzi, Luigi Tricarico and Giuseppe Casalino

J. Manuf. Mater. Process. 2024, 8(2), 55; https://doi.org/10.3390/jmmp8020055 - 04 Mar 2024

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Abstract

Lap joining of an aluminum AA6082-T6 plate and a UHSS steel plate coated with an Al-Si layer was performed using Probeless Friction Stir Spot Welding (P-FSSW). The dwell time and rotational speed were controlled in the range of 10–15 s and 1000–1500 rpm, [...] Read more.

Lap joining of an aluminum AA6082-T6 plate and a UHSS steel plate coated with an Al-Si layer was performed using Probeless Friction Stir Spot Welding (P-FSSW). The dwell time and rotational speed were controlled in the range of 10–15 s and 1000–1500 rpm, respectively. For all the samples, thermo-mechanical deformation occurred solely within the upper AA6082 plate. A refined grain structure was formed in the aluminum plate close to the surface. The dwell time was responsible for the intensity of the material flow, resulting in stirring between the Al-Si layer and the aluminum plate at 15 s. The microhardness distribution corresponded to the microstructure features. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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13 pages, 58262 KiB

Open AccessArticle

Modelling the Evolution of Phases during Laser Beam Welding of Stainless Steel with Low Transformation Temperature Combining Dilatometry Study and FEM

by Karthik Ravi Krishna Murthy, Fatma Akyel, Uwe Reisgen, Simon Olschok and Dhamini Mahendran

J. Manuf. Mater. Process. 2024, 8(2), 50; https://doi.org/10.3390/jmmp8020050 - 01 Mar 2024

Viewed by 950

Abstract

In this study, the evolution of volume fractions during laser beam welding (LBW) of stainless steel, with a specific focus on incorporating the low transformation temperature (LTT) effect using the dilatometer, has been proposed. The LTT effect refers to the phase transformations that [...] Read more.

In this study, the evolution of volume fractions during laser beam welding (LBW) of stainless steel, with a specific focus on incorporating the low transformation temperature (LTT) effect using the dilatometer, has been proposed. The LTT effect refers to the phase transformations that occur at lower temperatures and lead to the formation of a martensitic microstructure, which will significantly influence the residual stresses and distortion of the welded joints. In this research, the LTT conditions are achieved by varying the Cr and Ni content in the weld seam by varying the weld parameter, including laser power, welding speed and filler wire speed. The dilatometer analysis technique is employed to simulate the thermal conditions encountered during LBW. By subjecting the stainless steel samples to controlled heating and cooling cycles, the kinetics of the volume fractions can be measured using the lever rule and empirical method (KOP and Lee). The phase transformation simulation model is computed by integrating the thermal and metallurgical effects to predict the volume fractions in LBW joints and has been validated using dilatometer results. This provides valuable insight into the relationship between welding parameters and phase transformations in stainless steel with the LTT effect during laser beam welding. Using this relationship, the weld quality can be improved by reducing the residual stresses and distortion. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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12 pages, 7054 KiB

Open AccessArticle

In Situ Synchrotron Investigations of Beam Diameter Influence on Vapor Capillary Formation during Laser Beam Welding of Copper Alloy with a Blue Laser Beam Source

by Christoph Spurk, Frederik Dietrich, Marc Hummel, Arnold Gillner, Felix Beckmann, Julian Moosmann and Constantin Häfner

J. Manuf. Mater. Process. 2024, 8(2), 47; https://doi.org/10.3390/jmmp8020047 - 01 Mar 2024

Viewed by 1017

Abstract

Laser beam welding as a reliable tool for high-precision joining of batteries or microelectronics is more and more the choice for achieving reproducible results in production processes. In addition to a high automation capability, the precise control of the energy deposition into the [...] Read more.

Laser beam welding as a reliable tool for high-precision joining of batteries or microelectronics is more and more the choice for achieving reproducible results in production processes. In addition to a high automation capability, the precise control of the energy deposition into the material plays an important role, especially when highly reflective materials, such as copper or aluminum, must be welded together. Alongside the use of highly brilliant fiber lasers in the near-infrared range with a focal diameter of a few tens of micrometers, diode lasers in the wavelength range of 445 nm are increasingly being used. Here, beam diameters of a few hundred micrometers can be achieved. With a wavelength of 445 nm, the absorptivity in copper can be increased by more than a factor of 10 compared to a near-infrared laser beam sources in solid state at room temperature. This paper presents the in situ X-ray observation of laser welding processes on CuSn6 with a laser beam source with a wavelength of 445 nm using synchrotron radiation at DESY Petra III Beamline P07 EH4 in Hamburg, Germany. For the experiments, the laser radiation was focused via two separate optics to focal diameters of 362 µm and 609 µm. To characterize the dynamics of the vapor capillaries depending on the different focal diameters d_F, the parameters were varied with respect to laser power P_L and feed rate v. For the investigations, a synchrotron beam of 2 × 2 mm² in size with a photon energy of 89 keV was used, and the material samples were analyzed by means of phase-contrast videography to show the boundaries between solid, liquid, and gaseous material phases. The results of this paper show the welding depths achieved and how the geometry of the vapor capillary behaves by changing the focal diameter, laser power and feed rate. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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14 pages, 7991 KiB

Open AccessArticle

Investigation of Generatively Manufactured Components in a Sealed Welding Chamber Using the Tungsten Inert Gas Hot Wire Process

by Silvia Imrich, Kai Treutler and Volker Wesling

J. Manuf. Mater. Process. 2024, 8(1), 24; https://doi.org/10.3390/jmmp8010024 - 31 Jan 2024

Viewed by 1129

Abstract

To produce additively manufactured components, various process advantages can be combined by using the tungsten inert gas (TIG) hot wire process with ohmic wire preheating. Unlike other various gas metal arc welding processes, with TIG, it is possible to influence the material properties [...] Read more.

To produce additively manufactured components, various process advantages can be combined by using the tungsten inert gas (TIG) hot wire process with ohmic wire preheating. Unlike other various gas metal arc welding processes, with TIG, it is possible to influence the material properties by decoupling the energy supply and the welding filler material. Compared to the conventional TIG cold wire process, the hot wire process can achieve an increased deposition rate. To be able to use this combined process for the manufacturing of filigree components consisting of steel and titanium alloys, a system concept with a hermetically sealed welding chamber was developed. This concept is particularly designed for an individual use and is also intended to be used for producing prototypes and small quantities. In the investigations, the application of the TIG hot wire process is explored, regarding the material properties to be achieved in combination with the manufacturing plant concept developed with a sealed welding chamber. In this context, the mechanical-technological properties and detailed microstructural analyses are determined based on selected welding tests to evaluate and further develop the quality of the components produced. A final transfer of the findings to the process behavior by optimizing the interaction of the process parameters considered should lead to an increase in productivity, robustness, and reproducibility. The experimental setup’s potential for applicability in the field of additive manufacturing will be demonstrated based on this elaboration. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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19 pages, 4541 KiB

Open AccessArticle

Numerical Study of the Cold Metal Transfer (CMT) Welding of Thin Austenitic Steel Plates with an Equivalent Heat Source Approach

by Hichem Aberbache, Alexandre Mathieu, Nathan Haglon, Rodolphe Bolot, Laurent Bleurvacq, Axel Corolleur and Fabrice Laurent

J. Manuf. Mater. Process. 2024, 8(1), 20; https://doi.org/10.3390/jmmp8010020 - 26 Jan 2024

Viewed by 1661

Abstract

The CMT (cold metal transfer) arc welding process is a valuable joining method for assembling thin sheets, minimizing heat transfers, and reducing subsequent deformations. The study aims to simulate the CMT welding of thin stainless-steel sheets to predict temperature fields and deformations. Both [...] Read more.

The CMT (cold metal transfer) arc welding process is a valuable joining method for assembling thin sheets, minimizing heat transfers, and reducing subsequent deformations. The study aims to simulate the CMT welding of thin stainless-steel sheets to predict temperature fields and deformations. Both instrumented tests and numerical simulations were conducted for butt-welding of sheets with a thickness of 1 to 1.2 mm. Weld seam samples were observed to identify equivalent heat sources for each configuration. The electric current and voltage were monitored. Temperature measurements were performed using K-type thermocouples, as well as displacement measurements via the DIC (digital image correlation) technique. Thermomechanical simulations, considering phase changes and the actual seam geometry induced by filler material, were conducted using an equivalent heat source approach. A unique heat exchange coefficient accounting for thermal losses was identified. By incorporating these losses into thermal calculations, a good agreement was found between measured and calculated temperatures. Mechanical calculations allowed for the recovery of the horse saddle form after actual welding, with a relative difference of less than 10% in angular distortion between calculated and measured values. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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17 pages, 9895 KiB

Open AccessArticle

Challenges in Contacting Metal–Polymer Current Collectors in Pouch Cells

by Hakon Gruhn, Tobias Krüger, Malte Mund, Maja W. Kandula and Klaus Dilger

J. Manuf. Mater. Process. 2023, 7(6), 219; https://doi.org/10.3390/jmmp7060219 - 05 Dec 2023

Viewed by 1765

Abstract

Recent research focuses on replacing metal current collectors with metallized polymer foils. However, this introduces significant challenges during cell production, as manufacturing steps must be adapted. Currently, copper is used as the current collector on the anode side and aluminum on the cathode [...] Read more.

Recent research focuses on replacing metal current collectors with metallized polymer foils. However, this introduces significant challenges during cell production, as manufacturing steps must be adapted. Currently, copper is used as the current collector on the anode side and aluminum on the cathode side. These current collectors are then joined within the cell with an arrester tab. This step, known as contacting, is carried out industrially in pouch cells using ultrasonic welding or laser beam welding. However, since the polymer foil is electrically insulating, the current contacting procedures cannot be directly transferred to the metal–polymer current collectors. In this work, ultrasonic welding, laser beam welding, and a mechanical contacting method are considered, and the challenges arising from the material properties are highlighted. The properties of the joints are discussed as a function of the number of foils and the coating thickness of the metallization. It is demonstrated that successful contacting by ultrasonic welding and mechanical clamping is possible, as both mechanical strength and electrical conductivity are ensured by the joint. Laser beam welding was unsuccessful. Additionally, the electrical resistance is one to two orders of magnitude higher than that of pure aluminum and copper foils, which necessitates further optimization. Furthermore, ultrasonic welding is limited to welding 16 foils or fewer. This does not match industrial requirements. Consequently, novel approaches for contacting metal–polymer current collectors are required. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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13 pages, 3541 KiB

Open AccessArticle

Mechanical Investigation of Recyclability for Sustainable Use of Laser-Based Metal–Polymer Joints

by Christoph Wortmann, Maximilian Brosda and Constantin Häfner

J. Manuf. Mater. Process. 2023, 7(6), 210; https://doi.org/10.3390/jmmp7060210 - 28 Nov 2023

Viewed by 1439

Abstract

Metal–plastic hybrid components combine the strength of metal with the low density of plastic. Due to weight reduction, these components are becoming increasingly important. To reduce the need for raw materials, processes for the recyclability of hybrid compounds are being investigated to reuse [...] Read more.

Metal–plastic hybrid components combine the strength of metal with the low density of plastic. Due to weight reduction, these components are becoming increasingly important. To reduce the need for raw materials, processes for the recyclability of hybrid compounds are being investigated to reuse the metal part. The aim of this research is to characterize the mechanical bond strength after laser-based cleaning and reuse of the metal component. For this purpose, laser radiation is used to introduce microstructures into the metal surface. Afterwards, the polymer is joined to the metal component with laser radiation. As a reference of the initial mechanical bond strength, the joined samples are examined in a tensile testing machine. The polymer residues remaining in the structured metal surface are removed with different laser-based cleaning strategies. The metal is used again to generate another hybrid joined sample with a new polymer component. The results of the subsequent tests in the tensile testing machine are used for a detailed analysis of the reusability. As a result of this investigation, the laser-cleaned specimens showed significant improvements in bond strength compared to the uncleaned specimens. The process of laser-based cleaning for the reuse of the metallic part of hybrid joined components provides a fundamental procedure for improving the circular economy. In the future, this study should be validated in subsequent investigations on realistic components with complex geometries. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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22 pages, 7364 KiB

Open AccessEditor’s ChoiceArticle

A Selective Integration-Based Adaptive Mesh Refinement Approach for Accurate and Efficient Welding Process Simulation

by Hui Huang and Hidekazu Murakawa

J. Manuf. Mater. Process. 2023, 7(6), 206; https://doi.org/10.3390/jmmp7060206 - 24 Nov 2023

Viewed by 1396

Abstract

To save computational time and physical memory in welding thermo-mechanical analysis, an accurate adaptive mesh refinement (AMR) method was proposed based on the feature of moving heat source during the welding. The locally refined mesh was generated automatically according to the position of [...] Read more.

To save computational time and physical memory in welding thermo-mechanical analysis, an accurate adaptive mesh refinement (AMR) method was proposed based on the feature of moving heat source during the welding. The locally refined mesh was generated automatically according to the position of the heat source to solve the displacement field. A background mesh, without forming a global matrix, was designed to maintain the accuracy of stress and strain after mesh coarsening. The solutions are always carried out on the refined computational mesh using a selective integration scheme. To evaluate the performance of the developed method, a fillet welding joint was first analyzed via validation of the accuracy of conventional FEM by experiment. Secondly, a larger fillet joint and its variations with a greater number of degrees of freedom were analyzed via conventional FEM and current AMR. The simulation results confirmed that the proposed method is accurate and efficient. An improvement in computational efficiency by 7 times was obtained, and memory saving is about 63% for large-scale models. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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16 pages, 7098 KiB

Open AccessArticle

Investigation of Single-Pulse Laser Welding of Dissimilar Metal Combination of Thin SUS303 SS and Cu

by Ruining Huang, Xuehao Huang and Junqiang Feng

J. Manuf. Mater. Process. 2023, 7(5), 161; https://doi.org/10.3390/jmmp7050161 - 08 Sep 2023

Viewed by 1146

Abstract

The present study investigated the dissimilar metal combination of SUS303 stainless steel (SS) and pure copper C19210 by utilizing a fiber pulse laser to perform lap welding. The weld quality was evaluated through metallurgical and mechanical examinations, including scanning electron microscopy (SEM), optical [...] Read more.

The present study investigated the dissimilar metal combination of SUS303 stainless steel (SS) and pure copper C19210 by utilizing a fiber pulse laser to perform lap welding. The weld quality was evaluated through metallurgical and mechanical examinations, including scanning electron microscopy (SEM), optical microscopy (OM), energy dispersive spectroscopy (EDS), as well as tensile and shear tests. The cross-section of the weld joints was observed to examine the penetration inside the molten zone of the pulse laser welding. The incomplete weld penetration depth was confirmed by analyzing the molten pool geometry, which indicated that the penetration depth was proportional to the pulse heat energy input. EDS analysis demonstrated that interdiffusion and dissolution of Cu and SS occurred inside the weld pool, although only a limited amount of Cu was melted. Microhardness (MH) exploration revealed the hardness of the molten zone was lower than that of the heat-affected zone (HAZ) on the SS side, while the hardness on the Cu side, closer to the molten zone, was higher. The results of the tensile test indicated that the fracture occurred in the HAZ on the Cu side, displaying a dimpled fracture mode characteristic of ductile fracture. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques 2023)

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