Search results
1 – 10 of 90Mica Grujicic, Subrahmanian Ramaswami, Jennifer Snipes, Rohan Galgalikar, Ramin Yavari, Chian-Fong Yen, Bryan Cheeseman and Jonathan Montgomery
The purpose of this paper is to discuss the recently developed multi-physics computational model for the conventional Gas Metal Arc Welding (GMAW) joining process that has been…
Abstract
Purpose
The purpose of this paper is to discuss the recently developed multi-physics computational model for the conventional Gas Metal Arc Welding (GMAW) joining process that has been upgraded with respect to its predictive capabilities regarding the spatial distribution of the mechanical properties controlling the ballistic limit (i.e. penetration resistance) of the weld.
Design/methodology/approach
The original model consists of five modules, each dedicated to handling a specific aspect of the GMAW process, i.e.: electro-dynamics of the welding-gun; radiation-/convection-controlled heat transfer from the electric arc to the workpiece and mass transfer from the filler-metal consumable electrode to the weld; prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; and spatial distribution of the as-welded material mechanical properties. The model is upgraded through the introduction of the sixth module in the present work in recognition of the fact that in thick steel GMAW weldments, the overall ballistic performance of the armor may become controlled by the (often inferior) ballistic limits of its weld (fusion and heat-affected) zones.
Findings
The upgraded GMAW process model is next applied to the case of butt-welding of MIL A46100 (a prototypical high-hardness armor-grade martensitic steel) workpieces using filler-metal electrodes made of the same material. The predictions of the upgraded GMAW process model pertaining to the spatial distribution of the material microstructure and ballistic-limit-controlling mechanical properties within the MIL A46100 butt-weld are found to be consistent with general expectations and prior observations.
Originality/value
To the authors’ knowledge, the present work is the first reported attempt to establish, using computational modeling, functional relationships between the GMAW process parameters and the mechanical properties controlling the ballistic limit of the resulting weld.
Details
Keywords
M. Grujicic, J.S. Snipes, R. Galgalikar, S. Ramaswami, R. Yavari, C.-F. Yen, B.A. Cheeseman and J.S. Montgomery
The purpose of this paper is to develop multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process has been improved with respect to its…
Abstract
Purpose
The purpose of this paper is to develop multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process has been improved with respect to its predictive capabilities regarding the spatial distribution of the mechanical properties (strength, in particular) within the weld.
Design/methodology/approach
The improved GMAW process model is next applied to the case of butt-welding of MIL A46100 (a prototypical high-hardness armor-grade martensitic steel) workpieces using filler-metal electrodes made of the same material. A critical assessment is conducted of the basic foundation of the model, including its five modules, each dedicated to handling a specific aspect of the GMAW process, i.e.: first, electro-dynamics of the welding-gun; second, radiation/convection controlled heat transfer from the electric arc to the workpiece and mass transfer from the filler-metal consumable electrode to the weld; third, prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; fourth, the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; and fifth, spatial distribution of the as-welded material mechanical properties.
Findings
The predictions of the improved GMAW process model pertaining to the spatial distribution of the material microstructure and properties within the MIL A46100 butt-weld are found to be consistent with general expectations and prior observations.
Originality/value
To explain microstructure/property relationships within different portions of the weld, advanced physical-metallurgy concepts and principles are identified, and their governing equations parameterized and applied within a post-processing data-reduction procedure.
Details
Keywords
Michel Bellet and Makhlouf Hamide
The purpose of this paper is to present original methods related to the modeling of material deposit and associated heat sources for finite element simulation of gas metal arc…
Abstract
Purpose
The purpose of this paper is to present original methods related to the modeling of material deposit and associated heat sources for finite element simulation of gas metal arc welding (GMAW).
Design/methodology/approach
The filler deposition results from high-frequency impingements of melted droplets. The present modeling approach consists of a time-averaged source term in the mass equation for selected finite elements in the fusion zone. The associated expansion of the mesh is controlled by means of adaptive remeshing. The heat input includes a volume source corresponding to the droplets energy, for which a model from the literature is expressed in coherency with mass supply. Finally, an inverse technique has been developed to identify different model parameters. The objective function includes the differences between calculations and experiments in terms of temperature, but also shape of the fusion zone.
Findings
The proposed approach for the modeling of metal deposition results in a direct calculation of the formation of the weld bead, without any a priori definition of its shape. Application is shown on GMAW of steel 316LN, for which parameters of the model have been identified by the inverse method. They are in agreement with literature and simulation results are found quite close to experimental measurements.
Originality/value
The proposed algorithm for material deposit offers an alternative to the element activation techniques that are commonly used to simulate the deposition of filler metal. The proposed inverse method for parameter identification is original in that it encompasses an efficient and convenient technique to take into account the shape of the fusion zone.
Details
Keywords
Xiangman Zhou, Qihua Tian, Yixian Du, Yancheng Zhang, Xingwang Bai, Yicha Zhang, Haiou Zhang, Congyang Zhang and Youlu Yuan
The purpose of this paper is to find a theoretical reference to adjust the unsymmetrical arc shape and plasma flow of overlapping deposition in wire arc additive manufacturing…
Abstract
Purpose
The purpose of this paper is to find a theoretical reference to adjust the unsymmetrical arc shape and plasma flow of overlapping deposition in wire arc additive manufacturing (WAAM) and ensure the effect of the gas shielding and stable heat and mass transfer in deposition process. The multiphysical numerical simulation and physical experiment are used for validation.
Design/methodology/approach
In this study, welding torch tilt deposition and external parallel magnetic field–assisted deposition are presented to adjust the unsymmetrical arc shape and plasma flow of overlapping deposition, and a three-dimensional numerical model is developed to simulate the arc of torch tilt overlapping deposition and external parallel magnetic field–assisted overlapping deposition.
Findings
The comparison of simulated results indicate that the angle of welding torch tilt equal to 20° and the magnetic flux density of external transverse magnetic field equal to 0.001 Tesla are capable of balancing the electric arc and shielding gas effectively, respectively. The arc profiles captured by a high-speed camera match well with simulated results.
Originality/value
These studies of this paper can provide a theoretical basis and reference for the calibration and optimization of WAAM process parameters.
Details
Keywords
John P.H. Steele, Chris Mnich, Chris Debrunner, Tyrone Vincent and Stephen Liu
The purpose of this research is to develop closed‐loop control of robotic welding processes.
Abstract
Purpose
The purpose of this research is to develop closed‐loop control of robotic welding processes.
Design/methodology/approach
The approach being developed is the creation of three‐dimensional models of the weld pool using stereo imagining. These models will be used in a model‐based feedback control system. Fusion of more than one sensor type in the controller is used.
Findings
Three‐dimensional images can be produced from stereo images of GMAW‐p weld pools. This requires coordinating the image capture with the arc pulse to allow observation of the pool.
Research limitations/implications
This is a work in progress. The imaging is not being done in real time at this point in time. Future work will address this issue. Also, how the image information is to be used to make corrections within the controller is future work.
Practical implications
Closing the loop on GMAW welding will allow robotic automation of welding to proceed to a much broader degree of application.
Originality/value
This paper demonstrates that stereo imaging of out‐of‐position GMAW‐p weld pools is possible and the useful information can be obtained from these images. It also provides insights into the analysis required within the model‐based controller if one is to close the loop on the process specifically with regard to weld pool stability.
Details
Keywords
D. Katherasan, Jiju V. Elias, P. Sathiya and A. Noorul Haq
The purpose of this study is to optimize the process parameters (wire feed rate (F), voltage (V), welding speed (S) and torch angle (A)) in order to obtain the optimum bead…
Abstract
Purpose
The purpose of this study is to optimize the process parameters (wire feed rate (F), voltage (V), welding speed (S) and torch angle (A)) in order to obtain the optimum bead geometry (bead width (W), reinforcement (R) and depth of penetration (P)), considering the ranges of the process parameters using evolutionary algorithms, namely genetic algorithm (GA) and simulated annealing (SA) algorithm.
Design/methodology/approach
The modeling of welding parameters in flux cored arc welding process using a set of experimental data and regression analysis, and optimization using GA and SA algorithm.
Findings
The adequate mathematical model was developed. The multiple objectives were optimized satisfactorily by the GA and SA algorithms. The feasible solution results are very closer to the optimized results and the percentage error was found to be negligibly small.
Originality/value
The optimal welding parameters were identified in order to increase the productivity. The welding input parameters effect was found.
Details
Keywords
P. Sathiya, S. Aravindan, R. Jeyapaul, P.M. Ajith and A. Noorul Haq
The purpose of this paper is to optimize the gas metal arc welding (GMAW) process input parameters simultaneously considering the multiple output variables (bead width (BW), bead…
Abstract
Purpose
The purpose of this paper is to optimize the gas metal arc welding (GMAW) process input parameters simultaneously considering the multiple output variables (bead width (BW), bead height (BH) and depth of penetration (DP)).
Design/methodology/approach
Grey‐based Taguchi approach was used for designing the experiment, L27 orthogonal array was used which composed of three levels and 27 rows, which means that 27 experiments were carried out. Design of experiments was selected based on a four welding parameters with three levels each. The selected welding parameters for this paper are gas flow rate, voltage, travel speed and wire feed rate. The bead‐on‐plate welding trials are carried out on AISI 904L super austenitic stainless steel (SASS) sheets and evaluate the shape of the fusion zone depends upon a number of input parameters.
Findings
Bead‐on‐plate welding of 904L SASS sheet is successfully performed (without any cracks and discontinuity) by GMAW process and the bead profiles are measured. The predicted bead profiles have the better DP and lower BH and BW. It is found that the optimized setting values are improving the response values by 10 per cent.
Originality/value
The optimal welding conditions are identified in order to increase the productivity and minimize the total operating cost. The process input parameters effect is determined under the optimal welding combinations.
Details
Keywords
Md. Rumman Ul Ahsan, Ali Newaz Mohammad Tanvir, Taylor Ross, Ahmed Elsawy, Min-Suk Oh and Duck Bong Kim
Wire + arc additive manufacturing (WAAM) uses existing welding technology to make a part from metal deposited in an almost net shape. WAAM is flexible in that it can use multiple…
Abstract
Purpose
Wire + arc additive manufacturing (WAAM) uses existing welding technology to make a part from metal deposited in an almost net shape. WAAM is flexible in that it can use multiple materials successively or simultaneously during the manufacturing of a single component.
Design/methodology/approach
In this work, a gas metal arc welding (GMAW) based wire + arc additive manufacturing (WAAM) system has been developed to use two material successively and fabricate bimetallic additively manufactured structure (BAMS) of low carbon steel and AISI 316L stainless steel (SS).
Findings
The interface shows two distinctive zones of LCS and SS deposits without any weld defects. The hardness profile shows a sudden increase of hardness at the interface, which is attributed to the migration of chromium from the SS. The tensile test results show that the bimetallic specimens failed at the LCS side, as LCS has lower strength of the materials used.
Originality/value
The microstructural features and mechanical properties are studied in-depth with special emphasis on the bimetallic interface.
Details
Keywords
Zhang Hai-ou, Rui Wang, Liye Liang and Wang Gui-lan
The paper aims to introduce the fabrication of a medium steel aircraft part by hybrid deposition and micro-rolling technology (HDMR) and illustrate its advantages, microstructure…
Abstract
Purpose
The paper aims to introduce the fabrication of a medium steel aircraft part by hybrid deposition and micro-rolling technology (HDMR) and illustrate its advantages, microstructure features and mechanical properties of the part.
Design/methodology/approach
The HDMR technology contains two procedures happening almost at the same time: the welding deposition procedure and then the micro-rolling procedure. It takes the gas metal arc welding as the heat source to melt a metal wire and deposit metal in the welding deposition procedure. The metal just deposited is rolled synchronously by a micro roller following the welding torch in micro-rolling procedure almost at the same time layer by layer. The paper presents a contrast of the grain morphology of metal parts produced respectively by HDMR and freedom arc deposition (FAD) and the mechanical properties of metal parts of the same metal from HDMR casting, forging and FAD methods.
Findings
HDMR breaks the dendrite grain of welding beads into the fine crisscross grains. The mechanical properties of metal parts are improved distinctly by the micro-rolling procedure compared to casting, forging and FAD.
Practical implications
In addition, the application of HDMR technology has succeeded in the fabrication of an eligible aircraft metal part, which is quite difficult to achieve using other additive manufacturing (AM) or casting technologies.
Originality/value
HDMR has the advantage of equiponderance manufacturing by micro-rolling compared to other AM technologies. The metal part fabricated by HDMR technology obtains the fine crisscross grains and brings hope for AM metal components with excellent mechanical properties for aircraft applications.
Details
Keywords
Bing Liu, Hongyao Shen, Rongxin Deng, Zeyu Zhou, Jia’ao Jin and Jianzhong Fu
Additive manufacturing based on arc welding is a fast and effective way to fabricate complex and irregular metal workpieces. Thin-wall metal structures are widely used in the…
Abstract
Purpose
Additive manufacturing based on arc welding is a fast and effective way to fabricate complex and irregular metal workpieces. Thin-wall metal structures are widely used in the industry. However, it is difficult to realize support-free freeform thin-wall structures. This paper aims to propose a new method of non-supporting thin-wall structure (NSTWS) manufacturing by gas metal arc welding (GMAW) with the help of a multi-degree of freedom robot arm.
Design/methodology/approach
This study uses the geodesic distance on the triangular mesh to build a scalar field, and then the equidistant iso-polylines are obtained, which are used as welding paths for thin-wall structures. Focusing on the possible problems of interference and the violent variation of the printing directions, this paper proposes two types of methods to partition the model mesh and generate new printable iso-polylines on the split meshes.
Findings
It is found that irregular thin-wall models such as an elbow, a vase or a transition structure can be deposited without any support and with a good surface quality after applying the methods.
Originality/value
The experiments producing irregular models illustrate the feasibility and effectiveness of the methods to fabricate NSTWSs, which could provide guidance to some industrial applications.
Details