Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (101)
- Deutsch (25)
- Russisch (2)
- Italienisch (1)
- Mehrsprachig (1)
Schlagworte
- Laser beam welding (35)
- Solidification cracking (19)
- Laser metal deposition (11)
- Hybrid laser arc welding (10)
- Additive manufacturing (9)
- Laser welding (8)
- Hybrid laser-arc welding (7)
- Microstructure (7)
- Thick-walled steel (7)
- Critical strain (6)
- Laserstrahlschweißen (6)
- Numerical simulation (6)
- Additive Manufacturing (5)
- Hot cracking test (5)
- Laser Metal Deposition (5)
- Mechanical properties (5)
- Thermography (5)
- Additive Fertigung (4)
- Electromagnetic weld pool support (4)
- Elektromagnetische Schmelzbadunterstützung (4)
- Inconel 718 (4)
- Laser-Pulver-Auftragschweißen (4)
- Laserhybridschweißen (4)
- Stainless Steel (4)
- 316L (3)
- 9%Ni steel (3)
- High power laser beam welding (3)
- Hot cracking (3)
- Hybrid Laser Arc Welding (3)
- Laser hybrid welding (3)
- Mechanical mismatching (3)
- Partial penetration (3)
- Ti-6Al-4V (3)
- Weld pool shape (3)
- Aluminium (2)
- Austenitic stainless steels (2)
- Bulging effect (2)
- CTW-Test (2)
- Charpy impact toughness (2)
- Circumferential weld (2)
- Cryogenic steel (2)
- Defokussierung (2)
- Duplex AISI 2205 (2)
- Duplex stainless steel (2)
- Duplex steels (2)
- Edge effects (2)
- Electromagnetic weld pool control (2)
- End crater (2)
- Endkrater (2)
- Ferromagnetischer Stahl (2)
- Full penetration (2)
- Gap bridgeability (2)
- Hardness (2)
- Heißrissresistenz (2)
- Hot crack (2)
- Hybrid welding (2)
- In situ strain (2)
- LMD (2)
- Laser beam Welding (2)
- Laser-Hybridschweißen (2)
- Local critical strain (2)
- Matching ferritic welding electrode (2)
- Material transport (2)
- Melt pool dinamics (2)
- Nickel (2)
- Optical flow (2)
- Optical measurement (2)
- Optical measurment technique (2)
- Pipe manufacturing (2)
- Pipeline (2)
- Preheating (2)
- Process monitoring (2)
- Rundnaht (2)
- SMAW (2)
- Ship building (2)
- Single pass welding (2)
- Strain rate (2)
- Temperature behavior (2)
- Thermal cycles (2)
- Thermografie (2)
- Weld defects (2)
- Weld pool (2)
- Weldability (2)
- laser welding (2)
- Überlappbereich (2)
- 3D Druck (1)
- 3D printing (1)
- 3DDruck (1)
- 9%Ni steel, (1)
- AC magnetic field (1)
- Additiv (1)
- Analytical model (1)
- Artificial Intelligence (1)
- As-shielded arc welding (1)
- Aufbaustrategie (1)
- Austenitic welding electrode (1)
- Austenitische Stähle (1)
- Bending test (1)
- Build - up Strategy (1)
- Build-up strategy (1)
- Bulge effect (1)
- Bulging (1)
- CFD model (1)
- CFD-model (1)
- CO2 lasers (1)
- CTW test (1)
- Clad steels (1)
- Combined laser manufacturing (1)
- Contact element (1)
- Conventional Ni-based austenitic welding electrode (1)
- Convolutional neural network (1)
- Corrosion (1)
- Crater (1)
- Critical strain rate (1)
- Cryogenic Steel (1)
- DIC technique (1)
- Deposition rate (1)
- Dickblech (1)
- Different welding position (1)
- Digitale Bildkorrelationstechnik (1)
- Direct Energy Deposition (1)
- Direct Laser Metal Deposition (1)
- Direct energy deposition (1)
- Duplex (1)
- Duplex stainless steels (1)
- Edge quality (1)
- Electromagnetic Force (1)
- Electromagnetic Weld Pool Support (1)
- Electromagnetic backing (1)
- Electromagnetic stirring (1)
- Electromagnetic support (1)
- Electromagnetic weld pool support system (1)
- Elektromagnetische Badstütze (1)
- Elektromagnetische Schmelzbadsicherung (1)
- Elektromagnetische Schmelzbadstütze (1)
- Element transport (1)
- Equivalent heat source (1)
- Externally loaded test (1)
- FE-model (1)
- FEA (1)
- FEM (1)
- Ferritic welding electrode (1)
- Ferromagnetic steel (1)
- Ferromagnetic steels (1)
- Festigkeit (1)
- Fiber laser (1)
- Filler material distribution (1)
- Filler wire mixing (1)
- Fine-grained Steel (1)
- Finite element analysis (1)
- Finite element method (FEM) (1)
- Flow pattern (1)
- Fresnel reflection (1)
- Full Penetration (1)
- Full penetration welding (1)
- Fusion zone size (1)
- GTAW (1)
- Gas shielded arc welding (1)
- Hartmann effect (1)
- Heat flow (1)
- Heat source models (1)
- Heißriss (1)
- Heißrissanfälligkeit (1)
- High brightness (1)
- High power (1)
- High power laser keyhole welding (1)
- High strength steel (1)
- High-Power Welding (1)
- High-power Laserbeam Welding (1)
- High-power fibre laser (1)
- High-power laser beam (1)
- High-power laser beam welding (1)
- High-strength low-alloy steel (1)
- Hochfester Stahl (1)
- Hochleistungsschweißen (1)
- Hybrid Laser-Arc Welding (1)
- Hybrid-laser-arc welding (1)
- Hydrostatic and arc pressure exceed the Laplace pressure (1)
- IR-Spektroskopie (1)
- IR-spectroscopy (1)
- Imaging (1)
- Impact absorbed energy (1)
- Kaltzähe Stähle (1)
- Keyhole mode laser beam welding (1)
- Keyhole mode welding (1)
- Keyhole stability (1)
- Lamé curves approximation (1)
- Laser Beam Welding (1)
- Laser Metal Deposition (LMD) (1)
- Laser Metal Deposition; Laser Beam Welding; Duplex; Stainless Steel (1)
- Laser Powder Bed Fusion (1)
- Laser Pulver Auftragsschweißen (1)
- Laser beam weliding (1)
- Laser cutting (1)
- Laser keyhole welding (1)
- Laser metal deposition (LMD) (1)
- Laser metal fusion (1)
- Laser surfacing (1)
- Laser-Pulver-Auftragschweißen (LPA) (1)
- Laser-Pulver-Auftragschweißen; Laserstrahlschweißen, Duplex, Pufferschichten (1)
- Laser-beam welding, (1)
- Laser-hybrid welding (1)
- Laserpulverauftragschweißen (1)
- Laserstrahl-(Hybrid)schweißen (1)
- Laserstrahl-MSG-Hybridschweißen (1)
- Liquid Metal Embrittlement (1)
- Lokale Effekte (1)
- Longitudinal weld (1)
- Lorentz force (1)
- Low Temperature Toughness (1)
- Lötrissigkeit (1)
- MSG-Schweißen (1)
- MWIR (1)
- Macro Processing (Joining, Welding) (1)
- Magnetic bath support (1)
- Magnetic field (1)
- Magnetohydrodynamics (1)
- Magnettechnik (1)
- Maintenance (1)
- Manganese (1)
- Marangoni flow (1)
- Matching ferritic filler metal (1)
- Mechanical Properties (1)
- Mechanical-technological properties (1)
- Melt pool dynamics (1)
- Metal (1)
- Metal mixing (1)
- Microstructure Tensile strength (1)
- Misalignment of edges (1)
- Modellierung (1)
- Modified spray arc (1)
- Multi - physical modeling (1)
- Multi-physical modelling (1)
- Multispectral thermography (1)
- NIR (1)
- Natural convection (1)
- Ni-based austenitic filler metal (1)
- Ni-based austenitic welding electrode (1)
- Nickel-based superalloy (1)
- Novel metrology (1)
- Novel optical measurement (1)
- Novel optical metrology (1)
- Numerical modeling (1)
- Numerical modelling (1)
- Numerical process simulation (1)
- Numerical simulations (1)
- Optical measurement technique (1)
- Optische Emissionsspektroskopie (OES) (1)
- Oscillating magnetic field (1)
- Partial penetration welding (1)
- Pendelstrategie (1)
- Penetration depth (1)
- Pipe Welding (1)
- Pipeline steel X120 (1)
- Pipeline steel of grade X120 (1)
- Plasma cutting (1)
- Plasma-cut samples (1)
- Plume heating (1)
- Post-weld heat treatment (1)
- ProMoAM (1)
- Process chain (1)
- Process simulation (1)
- Pufferschichten (1)
- Repair and overhaul (1)
- Rissanfälligkeit (1)
- Rissbildung (1)
- SEP-1220-3 (1)
- SWIR (1)
- Schallemissionsanalyse (SEA) (1)
- Schweißeignung (1)
- Schweißen von kaltzähen Stählen (1)
- Schweißunregelmäßigkeiten (1)
- Secondary heat source (1)
- Selective Laser Melting (1)
- Self-restraint test (1)
- Shielding gases (1)
- Shipbuilding steel (1)
- Simulation (1)
- Single-pass welding (1)
- Software (1)
- Solidification (1)
- Solidification behaviour (1)
- Solidification craking (1)
- Spiralstrategie (1)
- Stainless steel (1)
- Stainless steels (1)
- Strain fields prediction (1)
- Strain measurement (1)
- Submerged arc welding (1)
- Superelliptic Lamé curves (1)
- TES (1)
- Temperature distribution (1)
- Temperature emissivity separation (1)
- Temperaturentwicklung (1)
- Tensile strength (1)
- Thermal analysis (1)
- Thermo-fluid flow (1)
- Thermographie (1)
- Thick Materials (1)
- Thick materials (1)
- Thick plate welding (1)
- Thick plates (1)
- Thick-Walled Steel (1)
- Thick-plate welding (1)
- Thick-walled Structures (1)
- Ti - 6Al - 4V (1)
- Toughness (1)
- Turbine blade (1)
- Turbine industry (1)
- Two-run welding technique (1)
- Untersuchung laserstrahlgeschweißter Verbindungen (1)
- V-notch impact toughness (1)
- Vacuum (1)
- Vakuum (1)
- Vapor recondensation (1)
- Weld imperfections (1)
- Weld pool geometry (1)
- Weld pool shape approximation (1)
- Weld pool support (1)
- Weld root (1)
- Welding simulation (1)
- Welding thermal cycle (1)
- Werkstofffragen (1)
- Werkstoffranking (1)
- Widerstandspressschweißen (1)
- Widerstandspunktschweißen (1)
- Windkraftanlagen (1)
- X8Ni9 (1)
- YAG lasers (1)
- cryogenic steel (1)
- hardness (1)
- hochfeste Stähle (1)
- laser hybrid welding (1)
- local effects (1)
- microstructure (1)
- tensile strength (1)
- thermal cycles (1)
- thick plate welding (1)
- vacuum (1)
- Ökonomische und ökologische Vorteile (1)
Organisationseinheit der BAM
- 9 Komponentensicherheit (93)
- 9.3 Schweißtechnische Fertigungsverfahren (91)
- 8 Zerstörungsfreie Prüfung (6)
- 8.0 Abteilungsleitung und andere (6)
- 1 Analytische Chemie; Referenzmaterialien (2)
- 1.9 Chemische und optische Sensorik (2)
- 9.0 Abteilungsleitung und andere (2)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (1)
Eingeladener Vortrag
- nein (11)
The application of hybrid laser-arc welding (HLAW) for joining closed circumferential welds is a challenge due to the high risk of forming a defective overlap area with a shrinkage void or solidification cracks in the material thickness. A series of HLAW experiments were performed to understand the development of a faulty overlap area when closing the circumferential weld. Welding trials on flat specimens and pipe segments were supported by numerical analyses in which the thermomechanical behavior of the welds in the overlap area was investigated. Different process control strategies were tested, including variations in defocusing levels and the overlap length. The newly developed HLAW head, including laser optics with a motor-driven collimation system, made it possible to defocus the laser beam during welding without disturbing the stability of the welding process. High-level defocusing of the laser beam of more than 40 mm relative to the specimen surface with a resulting beam diameter of > 2.9 mm, and in combination with a short overlap length of 15 mm, was promising with respect to the formation of a desired cup-shaped weld profile that is resistant to solidification cracks.
Laser metal deposition (LMD) as an additive manufacturing technique became increasingly important in recent years and thus the demand for component safety. This is the reason, for the need for reliable in-situ defect detection techniques. For laser beam weld seams an optical measurement technique based on an optical flow algorithm was successfully used to define the critical straining conditions that lead to hot cracking. This algorithm was adapted for bead-on-plate weld seams on LMD deposited layers of IN718 alloy while performing external strain on the specimen in an externally loaded hot cacking test facility. The resulting transversal hot cracks along the weld seam were localized via X-Ray inspection and the type of cracking confirmed by Scanning Electron Microscopy (SEM). The strain distribution was measured in the vicinity of the solidification front and correlated to the detected hot cracks. Based on the results this technique could be adopted for LMD experiments.
Duplex stainless steels combine the positive properties of its two phases, austenite and ferrite. Due to its good corrosion resistance, high tensile strength and good ductility it has multiple applications. But laser beam welding of duplex steels changes the balanced phase distribution in favor of ferrite. This results in a higher vulnerability to corrosion and a lower ductility. In this study different powder combinations consisting of duplex and nickel for coating layers by laser metal deposition are investigated. Afterwards laser tracks are welded, and the temperature cycles measured. The ferrite content of the tracks are analyzed by feritscope, metallographic analysis and Electron Backscatter Diffraction. The goal is the development of a powder mixture allowing for a duplex microstructure in a two-step process, where firstly the edges of the weld partners are coated with the powder mixture by LMD and secondly those edges are laser beam welded. The powder mixture identified by the pretests is tested in the two-step process and analyzed by metallographic analysis, energy dispersive X-ray spectroscopy and Vickers hardness tests. The resulting weld seams show a balanced duplex microstructure with a homogenous nickel distribution and a hardness of the weld seam similar to the base material.
The weld quality and the possible defect formation are directly determined by the weld pool shape and the thermo-fluid dynamics therein. In this paper, an untypical weld pool profile, i.e., elongated at its top and bottom but narrowed at the middle, is found experimentally and numerically in the wire feed laser beam welding. The detrimental influence of the weld pool narrowing on the element transport is analyzed and discussed. A magnetohydrodynamic technique is utilized to suppress the narrowing, aiming at a more homogenous element distribution. It is found that a low-temperature region is formed in the middle of the weld pool due to the interaction of the two dominant circulations from the top and bottom regions. The weld pool is significantly narrowed due to the untypical growth of the mushy zone in the low-temperature region, which results in a direct blocking effect on the downward flow and the premature solidification in the middle region. The Lorentz force produced by a transverse oscillating magnetic field shows the potential to change the flow pattern into a single-circulation type and the low-temperature-gradient region is mitigated.
Therefore, the downward transfer channel is widened, and its premature solidification is prevented. The numerical results are well validated by experimental measurements of metal/glass observation and X-ray fluorescence element mapping.
The strain field can reflect the initiation time of solidification cracks during the welding process. The traditional strain measurement is to first obtain the displacement field through digital image correlation (DIC) or optical flow and then calculate the strain field. The main disadvantage is that the calculation takes a long time, limiting its suitability to real-time applications. Recently, convolutional neural networks (CNNs) have made impressive achievements in computer vision.
To build a good prediction model, the network structure and dataset are two key factors. In this paper, we first create the training and test sets containing welding cracks using the controlled tensile weldability (CTW) test and obtain the real strain fields through the Lucas–Kanade algorithm. Then, two new networks using ResNet and DenseNet as encoders are developed for strain prediction, called StrainNetR and StrainNetD. The results show that the average endpoint error (AEE) of the two networks on our test set is about 0.04, close to the real strain value. The computation time could be reduced to the millisecond level, which would greatly improve efficiency.
AbstractLaser beam welding has become widely applied in many industrial fields in recent years. Solidification cracks remain one of the most common welding faults that can prevent a safe welded joint. In civil engineering, convolutional neural networks (CNNs) have been successfully used to detect cracks in roads and buildings by analysing images of the constructed objects. These cracks are found in static objects, whereas the generation of a welding crack is a dynamic process. Detecting the formation of cracks as early as possible is greatly important to ensure high welding quality. In this study, two end-to-end models based on long short-term memory and three-dimensional convolutional networks (3D-CNN) are proposed for automatic crack formation detection. To achieve maximum accuracy with minimal computational complexity, we progressively modify the model to find the optimal structure. The controlled tensile weldability test is conducted to generate long videos used for training and testing. The performance of the proposed models is compared with the classical neural network ResNet-18, which has been proven to be a good transfer learning model for crack detection. The results show that our models can detect the start time of crack formation earlier, while ResNet-18 only detects cracks during the propagation stage.
New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance industrial use of these techniques. An analytical model based on reaction-diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil-Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid-liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. Differential scanning calorimeter is used to measure the heat flow during the solid-liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation.
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 two thermal imaging cameras 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 above 10 mm penetration depth. 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.
AISI 2205 duplex stainless steel is used in a variety of industries, including the chemical and petrochemical industries. This is due to its high tensile strength combined with good ductility and corrosion resistance. However, in laser beam welding, these properties are negatively afected by the high cooling rates typical of the welding process. The resulting higher ferrrite content in the weld metal than in the base material leads to a reduction in the ductility and corrosion resistance of the welded joint. To overcome this problem, in this study, thick plates were coated by direct energy deposition (DED) prior to laser beam welding, whereas a duplex powder mixture containing a higher nickel concentration was used as a coating material. To improve the weld quality for the proposed two-step process, a method of additional material deposition instead of conventional tack weld was investigated. The resulting welded joints showed a well-balanced austenite to ferrite ratio and their properties and microstructure were verifed by metallographic analysis, electron backscatter difraction and Charpy impact testing. Using the standard ASTM G48 test method, it was found that the corrosion resistance of the welds was improved by a factor of four in average compared to the conventionally welded joints. The resulting properties, such as good ductility and corrosion resistance, of the welds with pre-coated edges showed good agreement with those of the base metal and confrmed the proposed two-step process as a promising alternative to the conventional approaches for welding thick duplex stainless steel plates.
In this contribution, we present a physically motivated heat source model for the numerical modeling of laser beam welding processes. Since the calibration of existing heat source models, such as the conic or Goldak model, is difficult, the representation of the heat source using so-called Lamé curves has been established, relying on prior Computational Fluid Dynamics (CFD) simulations.
Lamé curves, which describe the melting isotherm, are used in a subsequent finite-element (FE) simulation to define a moving Dirichlet boundary condition, which prescribes a constant temperature in the melt pool. As an alternative to this approach, we developed a physically motivated heat source model, which prescribes the heat input as a body load directly. The new model also relies on prior CFD simulations to identify the melting isotherm. We demonstrate numerical results of the new heat source model on boundary-value problems from the field of laser beam welding and compare it with the prior CFD simulation and the results of the Lamé curve model and experimental data.