Wissenschaftliche Artikel der BAM
Filtern
Dokumenttyp
Sprache
- Englisch (68)
Schlagworte
- Laser beam welding (22)
- Microstructure (6)
- Laser metal deposition (5)
- Resistance spot welding (5)
- Solidification cracking (5)
- Hybrid laser arc welding (4)
- Hybrid laser-arc welding (4)
- Mechanical properties (4)
- Thick-walled steel (4)
- Additive manufacturing (3)
- Artificial neural network (3)
- DED (3)
- Deep penetration (3)
- Fatigue tests (3)
- Hardness (3)
- Numerical modeling (3)
- Quality assurance (3)
- Tubular X-joints (3)
- Weld pool shape (3)
- Bulge effect (2)
- Critical strain (2)
- Data preparation (2)
- Directed Energy Deposition (2)
- Full penetration (2)
- Gap bridgeability (2)
- Grain refinement (2)
- High-power laser beam welding (2)
- L-PBF (2)
- Laser energy distribution (2)
- Laser hybrid welding (2)
- Laser-metal-deposition (2)
- Liquid metal embrittlement (2)
- Numerical modelling (2)
- Numerical process simulation (2)
- Numerical simulation (2)
- Optical flow (2)
- Porosity (2)
- Preheating (2)
- Process monitoring (2)
- Ray tracing (2)
- Refill friction stir spot welding (2)
- Single pass welding (2)
- Technical crack detection (2)
- Weld pool dynamics (2)
- Wire arc additive manufacturing (2)
- 9% Ni Steel (1)
- 9%Ni steel (1)
- AC magnetic field (1)
- AGIL (1)
- AHSS (1)
- AM feature integration (1)
- Additive Manufacturing (1)
- Advanced high strength steels (1)
- Advanced high-strength steel (1)
- AlMg0.7SiTiB filler wire (1)
- Aluminum bronze (1)
- Artificial Intelligence (1)
- Artificial intelligence (1)
- Automated arc welding (1)
- Automated manufacturing (1)
- Automotive (1)
- Bead-on-plate welds (1)
- Bending test (1)
- Bulge formation (1)
- Bulging (1)
- Bulging effects (1)
- CFD model (1)
- Carbon dioxide footprint (1)
- Charpy impact toughness (1)
- Cimensional Accuracy (1)
- Circumferential weld (1)
- Clustering (1)
- Columnar crystal growth (1)
- Computer vision (1)
- Condition monitoring (1)
- Convolutional neural network (1)
- Crack (1)
- Critical strain rate (1)
- Cryogenic steel (1)
- Crystal branch development (1)
- DED-EB (1)
- Damage prediction (1)
- Deep learning (1)
- Deep penetration laser beam welding (1)
- Digital Image Correlation (1)
- Digitalization (1)
- Directed energy deposition (1)
- Dissimilar joints (1)
- Distortion (1)
- Dual phase steel (1)
- Duplex AISI 2205 (1)
- Duplex steels (1)
- EBAM (1)
- EBSD (1)
- Edge quality (1)
- Electromagnetic backing (1)
- Electromagnetic stirring (1)
- Electromagnetic weld pool support (1)
- Electromagnetic weld pool support system (1)
- Element transport (1)
- Embedded electronics (1)
- End crater (1)
- Environmental impact categories (1)
- Filler material distribution (1)
- Filler wire (1)
- Filler wire mixing (1)
- Finite Element Method (1)
- Finite element method (FEM) (1)
- Finite element simulation (1)
- Flange width (1)
- Flüssigmetallinduzierte Rissbildung (1)
- Fusion zone size (1)
- Galvanized steel (1)
- General analytical solutions (1)
- Hardly separable problem (1)
- Heat Treatment (1)
- Heat source models (1)
- Heat treatment (1)
- High power laser beam welding (1)
- High process speeds (1)
- High strength steels (1)
- Hochfester Stahl (1)
- Hot cracking (1)
- Hot cracking test (1)
- Hybrid Laser arc Welding (1)
- Impact Absorbed Energy (1)
- Inconel 625 (1)
- Inconel 718 (1)
- Industrial and Manufacturing Engineering (1)
- Instumented indentation test (1)
- Integrated alignment features (1)
- Keyhole collapse (1)
- Lamé curves (1)
- Laser Metal Deposition (LMD) (1)
- Laser Powder Bed Fusion (1)
- Laser Welding (1)
- Laser cutting (1)
- Laser metal deposition (LMD) (1)
- Laser powder bed fusion (1)
- Laser powder-based directed energy deposition (1)
- Laser welding (1)
- Laser-plasma hybrid (1)
- Life cycle assessment (1)
- Liquid Metal Embrittlement (1)
- Local critical strain (1)
- Local fatigue approaches (1)
- Local fatigue spproaches (1)
- Magnesium Alloy (1)
- Magnesium alloy (1)
- Magnetic bath support (1)
- Magnetic field (1)
- Matching ferritic filler metal (1)
- Mechanical mismatching (1)
- Mechanical property (1)
- Melt pool dynamics (1)
- Metal mixing (1)
- Misalignment of edges (1)
- Model calibration (1)
- Model order reduction (1)
- Multi-materials joining (1)
- Multi-physical modelling (1)
- Multiple reflections (1)
- Ni-based austenitic filler metal (1)
- Nickel (1)
- Notch stress approach (1)
- Novel metrology (1)
- Numerical Simulation (1)
- Numerical welding simulations (1)
- Open science (1)
- Open source (1)
- Oscillating magnetic field (1)
- Oscillating vapor plume (1)
- PBF-LB/M (1)
- Partial penetration (1)
- Path planning (1)
- Penetration depth (1)
- Periodic solidification pattern (1)
- Pipe weld preparation (1)
- Plasma cutting (1)
- Plasma-cut samples (1)
- Plasma-transferred-arc (1)
- Plastic deformation (1)
- Post-weld heat treatment (1)
- Precipitation hardening aluminum alloys (1)
- Process chain (1)
- Proper generalized decomposition (1)
- Pulsed laser beam welding (1)
- Quality monitoring (1)
- Ray teacing (1)
- Ray-tracing methods (1)
- Research data management (1)
- SLM printed plasma torch (1)
- Seam geometry (1)
- Selective Laser Melting (1)
- Selektive-laser-melting (1)
- Ship building (1)
- Shipbuilding steel (1)
- Simulation (1)
- Single-pass welding (1)
- Software (1)
- Solidification (1)
- Stainless steels (1)
- Strain fields prediction (1)
- Strain measurement (1)
- Structural stress approach (1)
- Submerged arc welding (1)
- TIG welding (1)
- Tensile Strength (1)
- Tensile properties (1)
- Tensile resistance spot welding experiment (1)
- Texture (1)
- Thermal analysis (1)
- Thermal cycles (1)
- Thick materials (1)
- Thick plate welding (1)
- Thick-plate welding (1)
- Ti-6Al-4V (1)
- Two-dimensional solidification (1)
- Two-run welding technique (1)
- V-notch impact toughness (1)
- Vaporization (1)
- Weld pool (1)
- Welding (1)
- Welding Simulation (1)
- Welding simulation (1)
- Welding thermal cycle (1)
- Weldx (1)
- Widerstandspunktschweißen (1)
- Wire electron beam additive manufacturing (1)
- Wire feed laser beam welding (1)
- Wire-based additive manufacturing (1)
- Zink (1)
Organisationseinheit der BAM
- 9 Komponentensicherheit (68) (entfernen)
Directed energy deposition additive manufactured parts have steep stress gradients and an anisotropic microstructure caused by the rapid thermo-cycles and the layer-upon-layer manufacturing, hence heat treatment can be used to reduce the residual stresses and to restore the microstructure. The numerical simulation is a suitable tool to determine the parameters of the heat treatment process and to reduce the necessary application efforts. The heat treatment simulation calculates the distortion and residual stresses during the process. Validation experiments are necessary to verify the simulation results. This paper presents a 3D coupled thermo-mechanical model of the heat treatment of additive components. A distortion-based validation is conducted to verify the simulation results, using a C-ring shaped specimen geometry. Therefore, the C-ring samples were 3D scanned using a structured light 3D scanner to compare the distortion of the samples with different post-processing histories.
In additive manufacturing (AM) directed energy deposition (DED), parts are built by welding layers of powder or wire feedstock onto a substrate with applications for steel powders in the fields of forging tools, spare parts, and structural components for various industries. For large and bulky parts, the choice of toolpaths influences the build rate, the mechanical performance, and the distortions in a highly geometry-dependent manner. With weld-path lengths in the range of hundreds of meters, a reliable, automated tool-path generation is essential for the usability of DED processes. This contribution presents automated tool-path generation approaches and discusses the results for arbitrary geometries. Socalled “zig-zag” and “contour-parallel” processing strategies are investigated and the tool-paths are automatically formatted into machine-readable g-code for experimental validation to build sample geometries. The results are discussed in regard to volume-fill, microstructure, and porosity in dependence of the path planning according to photographs and metallographic cross-sections.
This paper demonstrates that the instrumented indentation test (IIT), together with a trained artificial neural network (ANN), has the capability to characterize the mechanical properties of the local parts of a welded steel structure such as a weld nugget or heat affected zone.
Aside from force-indentation depth curves generated from the IIT, the profile of the indented surface deformed after the indentation test also has a strong correlation with the materials’ plastic behavior. The profile of the indented surface was used as the training dataset to design an ANN to determine the material parameters of the welded zones. The deformation of the indented surface in three dimensions shown in images were analyzed with the computer vision algorithms and the obtained data were employed to train the ANN for the characterization of the mechanical properties. Moreover, this method was applied to the images taken with a simple light microscope from the surface of a specimen. Therefore, it is possible to quantify the mechanical properties of the automotive steels with the four independent methods: (1) force-indentation depth curve; (2) profile of the indented surface; (3) analyzing of the 3D-measurement image; and (4) evaluation of the images taken by a simple light microscope. The results show that there is a very good Agreement between the material parameters obtained from the trained ANN and the experimental uniaxial tensile test. The results present that the mechanical properties of an unknown steel can be determined by only analyzing the images taken from its surface after pushing a simple indenter into its surface.
The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure.
Resistance spot welding is an established joining process for the production of safetyrelevant components in the automotive industry. Therefore, consecutive process monitoring is essential to meet the high quality requirements. Artificial neural networks can be used to evaluate the process parameters and signals, to ensure individual spot weld quality. The predictive accuracy of such algorithms depends on the provided training data set, and the prediction of untrained data is challenging. The aim of this paper was to investigate the extrapolation capability of a multi-layer perceptron model. That means, the predictive performance of the model was tested with data that clearly differed from the training data in terms of material and coating composition. Therefore, three multi-layer perceptron regression models were implemented to predict the nugget diameter from process data. The three models were able to predict the training datasets very well. The models, which were provided with features from the dynamic resistance curve predicted the new dataset better than the model with only process parameters. This study shows the beneficial influence of process signals on the predictive accuracy and robustness of artificial neural network algorithms.
Especially, when predicting a data set from outside of the training space.
The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and an infrared camera is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs more frequently during partial penetration above 6 mm and complete penetration above 8 mm penetration depth, respectively. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root.
The study deals with the determination of the influence of an externally applied oscillating magnetic field on the melt pool dynamics in high power laser beam and hybrid laser arc welding processes. An AC magnet was positioned under the workpiece which is generating an upward directed electromagnetic force to counteract the formation of the droplets. To visualise the melt flow characteristics, several experiments were carried out using a special technique with mild steel from S355J2 with a plate thickness of up to 20 mm and a quartz glass in butt configuration. The profile of the keyhole and the melt flow were recorded with a highspeed camera from the glass side. Additionally, the influence of the magnetic field orientation to the welding direction on the filler material dilution on laser hybrid welding was studied with variating oscillation frequency. The element distribution over the whole seam thickness was measured with X-ray fluorescence (XRF). The oscillation frequency demonstrated a great influence on the melt pool dynamics and the mixing of the elements of the filler wire. The highspeed recordings showed, under the influence of the magnetic field, that the melt is affected under strong vortex at the weld root, which also avoids the formation of droplets.
One of the challenges of the high-power hybrid laser welding of thick steels is the sensitivity of the process of the process to manufacturing tolerances. This usually leads to a time-consuming preparation of the welding edges, such as milling. The study deals with the influence of the edge quality of milled and plasma-cut steel made of S355J2 with a wall thickness of 20 mm on the laser hybrid welded seam quality. Furthermore, the gap bridgeability and the tolerances towards edge misalignment was investigated. An AC magnet was used as backing support to prevent sagging and positioned under the workpiece, to generate an upwards directed electromagnetic pressure. The profiles of the edges and the gap on the top and root side were measured using a digital camera. Single-pass laser hybrid welds of plasma-cut edges could be welded using a laser beam power of just 13.7 kW. A gap bridgeability up to 2 mm and misalignment of edges up to 2 mm could be achieved successful. Additionally, the independence of the cutting side and the welding side was shown, so that samples were welded to the opposite side to their cutting. For evaluation of internal defects or irregularities, X-ray images were carried out. Charpy impact strength tests were performed to determine the toughness of the welds.
Wire arc additive manufacturing enables the production of near-net shape large-volume metallic components leveraging an established industrial base of welding and cladding technology and adapting it for layer-wise material deposition. However, the complex relationship between the process parameters and resulting mechanical properties of the components still remains challenging. In case of high-strength Al-Mg-Si aluminum alloys, no commercial filler wires are yet available due the high susceptibility of solidification cracking as well as the necessary efforts to obtain acceptable mechanical properties. To address this need, we evaluated a novel filler wire based on AlMg0.7Si doped with a Ti5B1 master alloy to foster fine equiaxed grains within the deposited metal. The correlation between the process parameters and component quality was examined by analyzing the size and distribution of pores as well as the grain morphology. Furthermore, we evaluated the influence of different post-weld heat treatment strategies to achieve mechanical properties corresponding to the reference wrought material. We demonstrated that fine equiaxed grains in the weld metal reduced the susceptibility of solidification cracking significantly. The novel AlMg0.7Si-TiB (S Al 6063-TiB) filler wire facilitated wire arc additive manufacturing of high-strength aluminum components with mechanical properties that were almost as superior as the corresponding wrought base material.
The application of magnesium (Mg) inevitably involves dissimilar welding with steel. A novel solid state spot welding method, refill friction stir spot welding (refill FSSW), was utilized to weld AZ31 Mg alloy to galvanized DP600 steel. Although Mg/Fe is an immiscible alloy system, defect-free welds with high strength were successfully obtained in a wide parameter window. The results of microstructure, interfacial reactions, and mechanical properties are reported to reveal the underlying joining mechanism. Due to the melting of Zn coating and subsequent Mg-Zn reactions, Mg-Zn eutectic and intermetallic compounds were detected within welds. Heterogeneous interfacial reactions occur along Mg/steel interface, and the relationship between interfacial structure and fracture behavior was investigated. The joining mechanism is associated with Zn coating and Fe-Al layer: 1) the presence of Zn coating is beneficial for achieving high-quality welding between Mg and steel, it protects the interface from oxidation and contributes to brazing of the weld; 2) the Al present in Mg alloy reacts with Fe, resulting in the growth of Fe-Al layer, which contributes to the diffusion bonding in the interface. The overall results clearly show that Refill FSSW is a competitive welding method for joining Mg and galvanized steel.