ProgramMaster Logo
Conference Tools for 2022 AWS Professional Program
Register as a New User
Submit An Abstract
Propose A Symposium
Presenter/Author Tools
Organizer/Editor Tools
About this Abstract
Meeting 2022 AWS Professional Program
Symposium 2022 AWS Professional Program
Presentation Title Impact of Beam Deflection on Porosity during Keyhole Mode Laser Welding of Aluminum Alloys
Author(s) Abhirup Saha, Jeffrey Rodelas, Michael Maguire, Tarasankar DebRoy, Todd Palmer
On-Site Speaker (Planned) Abhirup Saha
Abstract Scope Introduction: High-strength aluminum alloys are susceptible to the formation of porosity and solidification cracking during laser welding. The porosity is generally attributed to the collapse of the keyhole driven by an imbalance between the vapor recoil pressure formed within the keyhole and surface tension forces driven by fluid flow in the surrounding liquid metal in the fusion zone. Several mitigation approaches using shielding gases that are soluble in the molten metal and reducing the ambient pressure have demonstrated some success in other material systems. Beam manipulation through the use of galvo-driven optics has become more widely available and allows the beam path and oscillation frequency to be tailored to alter the fluid flow patterns within the fusion zone. This technique has shown some initial promise for decreasing the rather high levels of porosity obtained during the laser welding of high-strength Al alloys. However, the role of the beam path and oscillation frequency on the morphology and distribution of the pores within the fusion zone has been largely unexplored. Experimental Procedure: A series of laser welds were fabricated on butt joints comprised of AA6061 and AA4047 aluminum alloy plates using a multi-mode Yb-fiber laser equipped with a D30 wobble head (IPG Photonics) that produced a beam diameter of 55 Ám. Circular scanning patterns with an amplitude of 0.4mm and 0.8mm and frequency ranging 150Hz and 1000Hz were used to fabricate the different welds at a laser power of 800 W and travel speeds between 22 mm/sec and 50 mm/sec. The alloy combination was selected to mitigate the potential for solidification cracking in 3.175 mm plate material. Weld dimensions were measured from cross-sections obtained from each welding condition using Zeiss Smartzoom optical microscope. Pores present within the welds were characterized using X-ray Computed Tomography (XCT) techniques, a GE v|tome|x L300 system operated at an accelerating voltage of 210 kV and current of 70 μA with a 0.5 mm Cu filter to produce a voxel size of approximately 0.016mm. The size and morphology of the individual pores were measured from three-dimensional representations of the welds processed using Avizo 9.7.0 scans and analyzed using ImageJ, an open-source image-processing platform. Results and Discussion: The use of circular beam deflection during laser welding impacts both the energy density distribution as well as the resulting weld shape and dimensions. In general, the addition of circular deflection to the beam path by varying the diameter of the circular beam path and the frequency at which the beam traverses, the energy density distribution, and heat input are impacted even for the same laser power and travel speed. By changing the energy density distribution and beam path, corresponding changes in the weld profiles are observed. Increase in the diameter of the circular deflection path from 0.4 mm to 0.8 mm produced wider yet shallower welds with widths on the order of 1.6 to 1.8 mm and depths on the order of 1.4 mm. Changes in the frequency of the beam oscillation, however, had little impact at the smaller beam deflection but resulted in shallower pools when the frequency was increased at the larger beam amplitude. While changes in weld dimensions are expected, the use of beam deflection has been mainly employed to attempt to mitigate the formation of keyhole collapse porosity, which is common in laser welding of high-strength Al alloys. By examining the welds in a three-dimensional fashion, the size, morphology, and distribution of pores for various beam deflection parameters were able to be quantified. While increasing the frequency up to a level of 300 Hz, lower porosity levels in the different welds were noticed, but the pores were not completely removed for keyhole mode welds and comprised of a bimodal distribution of pore sizes. The smaller pores were largely spherical, with sphericity values above 0.95, and distributed at locations corresponding to 80% of the weld depth. On the other hand, the larger pores were elongated in shape and displayed sphericity values below 0.85. Conclusion: Emerging beam deflection technologies are being pursued as a means for mitigating and eliminating the pores resulting from keyhole collapse during the laser welding of aluminum alloys. The application of circular beam deflections at different diameters or amplitudes and frequencies have been evaluated during the laser welding of AA6061 and AA4047 alloys, and the pore size, morphology, and distribution have been quantified. While different oscillation parameters have an effect on the pore distribution, number, size, and shape, the pores are not completely removed from the welds. Porosity reaches the lowest measured levels (0.49%) at the smallest amplitude (0.4mm) and a frequency of 300Hz frequency, with the pores being rather small and spherical and located near the weld root region, corresponding to the bottom of the keyhole.
Proceedings Inclusion? Undecided


2020 Thomas Medal Presentation: Keeping Pace with Change
Addressing Materials Challenges and Other Barriers to the Future of Additive Manufacturing
An AI-based Vision Methodology for Self-guided Seam Tracking in Gas Metal Arc Welding
An Investigation into the Effects of Stir Zone Chemistry on Fracture Toughness in Friction Stir Welded Pipeline Grade Steel
Analysis of Temperature and Velocity Fields in the GTAW Arc for Argon
Application of Polarity Switching Capacitor Discharge Welding to Aluminum Sheet Structures
Buried Arc GMAW for Single Pass Single Sided Erection Joints onboard Ships
Carbonitride Development and Heat Treatment Response of Additively Manufactured 17-4 PH Stainless Steel with Variations in Composition
Characterization of Dissimilar Materials 410 Martensite Stainless Steel and Mild Steel Component Produced by Wire Arc Additive Manufacturing
Deleterious Phase Avoidance in Additively Manufactured Functional Gradients through Path Planning
Developing an Automated Defect Detection TIG Welding Robot with a future Adaptive Implementation
Development of a Temperature-Dependent Material Property Database for DH36 Steel
Droplet Temperature in GMAW
Effect of Composition on Solidification Behavior and Resultant Microstructure in Dissimilar Electron Beam Welds between Commercially Pure Iron and Nickel
Energy Balance in Gas Metal Arc Welding
Evaluating the Carbide Precipitation Behavior During Short Term Tempering and its Influence on Impact Toughness.
Evaluation of Spatter Production with Deep Learning Algorithms
Evolution of Analytical Modelling Approaches for Resistance Spot Welding: A Historical Perspective
Fatigue Properties of Dissimilar Aluminum to Steel Welds Joined by Ultrasonic Interlayered Resistance Spot Welding Process
Hardness Prediction by Incorporating Heat Transfer and Molten Pool Fluid Flow in a Multi-pass, Multi-layer Weld for Onsite Repair of CSEF Grade 91 Steel
High Speed Video (HSV) and Synchronized Data Acquisition (DAQ) to Observe Welding Process Stability
How to Accurately Monitor the Weld Penetration from Dynamic Weld Pool Serial Images using CNN-LSTM Deep Learning Model?
Hybrid Manufacturing: Combining Additive Friction Stir Deposition, Metrology, and Machining
IIW Commission I Activities on Additive Manufacturing
Impact of Beam Deflection on Porosity during Keyhole Mode Laser Welding of Aluminum Alloys
In-situ Liquid Nitrogen Cryogenic Cooling for Interpass Control in High-Duty Cycle Wire Arc Additive Manufacturing of Large Components for Navy Applications
Influence of Microstructure on the Mechanism of Hydrogen-assisted Cracking in Dissimilar Metal Welds for Refinery Application
Integrated Modeling of Defect Formation during Deep Penetration Laser Welding of Creep Resistant Nickel Base Alloys
Investigation of Fe-10 wt.% Ni Steel Weld Metal Hydrogen Induced Cracking Susceptibility using the Gapped Bead on Plate (GBOP) Test
Large-Scale Hybrid Manufacturing using Wire Arc Additive Manufacturing
Machine Learning-based Process Characterization and Efficient Adaptive Control in Robotic Arc Welding
Material Characterization of Grade 91 Steel Welds using Micro-resolution Ultrasonic Imaging System.
Mechanical Design and Development of a Five Degree-of-Freedom TIG Welding Robot
Meta-Analysis of Fatigue Properties in Additively Manufactured 316L Austenitic Stainless Steel
Micro Cross Weld Tensile Testing of Dissimilar Metal Welds using Digital Image Correlation
Micro GTAW Applied to a Battery Pack for Racing Applications
Microstructure and Mechanical Properties of Electron Beam Additively Manufactured Ti-6Al-4V
Optimizing Productivity of Hyper Duplex Stainless Steels Overlay while Avoiding Sigma Phase Formation
Phase Transformation Behavior of Fe-10wt.% Ni Steel Weld Metal
Predicting Operation Windows for High-Frequency Induction Aluminum Tube Welding through Machine Learning
Process-Feature-Microstructure-Property Relationships for A9628 Directed Energy Deposition Additive Manufactured Steel Components
Real-Time Recognition of Arc Weld Pool Using Image Segmentation Network
Role of Standards in Welding Safety
Scaling Analysis of Thermal and Mechanical Process in Friction Stir Welding
The Effects of Post-Weld Processing on Friction Stir Welded Additive Manufactured AlSi10Mg
The Influence of Boride Phase Transformations on Heat-Affected Zone Liquation Cracking Susceptibility in Laser Welded 304L Stainless Steel
The Influence of Dynamic Behaviors Characteristics of Molten Pool on the Weld Formation during the High Speed Laser Welding
The International Institute of Welding: Strategic Directions for Welding and Joining Research and Industrial Applications
Use of Low Transition Temperature Steel Alloys In Welded Overlays for High Wear Applications
Welding Investigation of Wrought FeMnAl Steel
WeldVac – A Quiet, Clean Metal Removal System

Questions about ProgramMaster? Contact