Investigation of Fusion Weldments of Semi-Solid Aluminium A356 Alloy: Pool Geometry and Microstructure

2013 ◽  
Vol 765 ◽  
pp. 751-755 ◽  
Author(s):  
S. Sandhya ◽  
G. Phanikumar
Keyword(s):  
Fusion Zone ◽  
A356 Alloy ◽  
Welding Process ◽  
Fusion Welding ◽  
Thermal Gradients ◽  
Dendritic Microstructure ◽  
Evolution Simulation ◽  
Globular Microstructure ◽  
Gas Tungsten Arc ◽  
Semi Solid

A fusion welding technique to join a semi-solid processed A356 cast plate is explored using Gas Tungsten Arc Welding (GTAW). Semi-solid metal (SSM) billets of non-dendritic microstructure produced by rheocasting in a mould placed inside a linear electromagnetic stirrer were used for this study. GTAW experiments were conducted to simulate different thermal gradients near the fusion zone. The geometries of the weld pool as well as the temperature gradient in the fusion boundary were measured to understand the microstructure evolution. Simulation of the welding process was performed to aid in the analysis. Quantitative metallography provided the shape factor as a measure of globularity of the primary a-Al phase. Based on the studies, a model has been proposed to explain the observation of globular microstructure in the fusion zone of the welds. Conclusions show a positive correlation of thermal gradient with globular microstructure formation in this class of alloys.

scholarly journals Multi-pass friction stirred clad welding of dissimilar joined AA6061 aluminium alloy and brass

2018 ◽  
Vol 12 (4) ◽  
pp. 4285-4299
Author(s):  
Nora Osman ◽  
Zainuddin Sajuri ◽  
Mohd Zaidi Omar
Keyword(s):  
Mechanical Properties ◽  
Tool Steel ◽  
Microstructural Analysis ◽  
Welding Process ◽  
Fusion Welding ◽  
Tool Steels ◽  
Aa6061 Aluminium Alloy ◽  
Aisi D2 ◽  
Semi Solid ◽  
Aisi D2 Tool Steel

Tool steels are commonly used to cut metal materials due to their distinctive hardness, resistance to abrasion and deformation. However, tool steels are difficult to be joined using conventional fusion welding process. In this study, a thixotropic property of metal was utilised to butt-join an AISI D2 tool steel by using uncommon direct partial re-melting (DPRM) method. A high frequency of induction heating is used to apply the DPRM method. From the recent study, there are many methods in achieving the globular microstructure with the success of semi-solid joining process. Though, very less information on the microstructural effect of semi-solid joining on the mechanical properties was reported. This study aims to analyse the effect of uniaxial force on the microstructural evolution and mechanical properties of the thixo-joint of D2 tool steel. The microstructural analysis showed the diffusion occurred between the grains of the thixo-joint sample with 2.5 N uniaxial force. The maximum strength of the thixo-joint sample with force was 652 MPa. This was slightly higher than the as-received sample and the thixo-joint sample without force. The average hardness value of the thixo-joint sample was 400 HV due to the transformation of ferrite to the metastable austenite.

scholarly journals Residual stresses in gas tungsten arc welding: a novel phase-field thermo-elastoplasticity modeling and parameter treatment framework

2021 ◽  
Author(s):  
Baharin Ali ◽  
Yousef Heider ◽  
Bernd Markert
Keyword(s):  
Residual Stresses ◽  
Phase Field ◽  
Arc Welding ◽  
Welding Process ◽  
Gas Tungsten Arc Welding ◽  
Fusion Welding ◽  
Isotropic Hardening ◽  
Melting Front ◽  
Gas Tungsten Arc ◽  
Gas Tungsten

AbstractThe fusion welding process of metallic components, such as using gas tungsten arc welding (GTAW), is often accompanied by detrimental deformations and residual stresses, which affect the strength and functionality of these components. In this work, a phase-field model, usually used to track the states of phase-change materials, is embedded in a thermo-elastoplastic finite element model to simulate the GTAW process and estimate the residual stresses. This embedment allows to track the moving melting front of the metallic material induced by the welding heat source and, thus, splits the domain into soft and hard solid regions with a diffusive interface between them. Additionally, temperature- and phase-field-dependent material properties are considered. The J2 plasticity model with isotropic hardening is considered. The coupled system of equations is solved in the FE package FEniCS, whereas two- and three-dimensional initial-boundary-value problems are introduced and the results are compared with reference data from the literature.

Study of Microstructural Evolution and Phase’s Morphology after Partial Remelting in A356 Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 367-372 ◽  
Author(s):  
A. Mahdavi ◽  
M. Bigdeli ◽  
M. Hajian Heidary ◽  
F. Khomamizadeh
Keyword(s):  
Dendritic Structure ◽  
A356 Alloy ◽  
Intermetallic Phases ◽  
Effective Parameters ◽  
Dendritic Microstructure ◽  
Globular Structure ◽  
Needle Morphology ◽  
Sima Process ◽  
Semi Solid ◽  
Globular Form

In this work, effective parameters of SIMA process to obtain non dendritic microstructure in A356 alloy were investigated. In addition, the effect of SIMA process on the evolution of morphology of silicon and intermetallic phases in this alloy was studied. Microstructure images obtained from optical microscopy and SEM observation showed that increase in plastic work up to 40% and then holding of samples in the semi solid state at temperature of 580oC, causes that primary dendritic structure changes to non dendritic, fine and globular structure, but optimum reheating time completely depended on initial thickness of samples. If all parameters of SIMA process are the same, the grain boundaries of thinner samples begin to wet and following globalization will be completed in shorter reheating time rather than thicker ones. Moreover, it was found that the intermetallic phases lost their angular or needle morphology and gradually changed to rounded morphology and even to globular form. Also the optimum reheating time thoroughly depends on primary casting microstructure as the finer casting microstructure begin to globalize faster than thicker one under more little stains.

The characterization of corrosion resistance in the Ti-6Al-4V alloy fusion zone using a gas tungsten arc welding process

2009 ◽  
Vol 24 (12) ◽  
pp. 3680-3688 ◽  
Author(s):  
L.M. Wang ◽  
H.C. Lin
Keyword(s):  
Corrosion Resistance ◽  
Oxide Layer ◽  
Fusion Zone ◽  
Arc Welding ◽  
Welding Process ◽  
Heat Treatments ◽  
Gas Tungsten Arc Welding ◽  
Gas Tungsten Arc ◽  
Gas Tungsten ◽  
Arc Welding Process

The Ti-6Al-4V sheet alloys were welded by using a common gas tungsten arc welding process. In this work, we study the correlation of corrosion resistance and oxide layer structure produced after commonly used industrial heat treatments. We also study the oxide scales that were formed as a result of the heat-related treatment/aging process. The results indicate that better corrosion resistance of the Ti-6Al-4V alloy weldment can be obtained and significantly improved by a solution treatment plus an artificial aging (ST+AA) treatment, owing to the enhanced intensity of TiO2, V2O5, and Al2O3 oxides that compacted and grew on the surface of fusion zone. The newly found γ-TiAl and α2-Ti3Al particles that nucleated in the fusion zone due to different heat treatments do affect the composition of the oxide layer. The possible mechanism for this oxide layer formation in the fusion zone is discussed.

The Rapid Cooling Effect on Microstructure of Nickel-Based Alloys Welding Joint

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
LiBing Zhao ◽  
Zhentai Zheng ◽  
Zelong Wang ◽  
Jianing Qi ◽  
Yunfeng Lei ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Fusion Zone ◽  
Welding Process ◽  
High Heat ◽  
Liquid Films ◽  
Hot Cracking ◽  
Fusion Welding ◽  
Rapid Cooling ◽  
Haz Width ◽  
Equiaxed Grains

Fusion welding of nickel-based alloys is often associated with coarse grains and severe segregation, which finally results in the increase of hot cracking susceptibility and poor mechanical properties. Conventional gas tungsten arc welding (GTAW) can aggravate these phenomena, which is mainly due to its high heat input and low cooling rate. In this paper, the cooling rate was enhanced by spraying liquid nitrogen during the welding process. Compared to conventional GTAW, the rapid cooling produced narrower heat affected zone (HAZ) width and more equiaxed grains in the fusion zone, thus higher hardness distribution was also achieved in this condition. In addition, γ′ phase exhibited a dispersed distribution, and segregation has been improved. The results show that the HAZ width is decreased by about 50%, and the fusion zone consisting of the finest equiaxed grains and the lowest segregation was obtained, when the heat sink located on one side 10 mm away from the weld centerline. Also, fine equiaxed grains and the dispersed distribution of γ′ phase could improve the grain boundary strength and reduce the incidence of liquid films along grain boundaries, contributing to prevent nickel-based alloys welding hot cracking from initiating.

scholarly journals Effect of uniaxial load on microstructure and mechanical properties of Thixo-joint AISI D2 tool steel

2019 ◽  
Vol 13 (2) ◽  
pp. 5006-5020 ◽  
Author(s):  
F. Adnan ◽  
Z. Sajuri ◽  
M. Z. Omar
Keyword(s):  
Mechanical Properties ◽  
Tool Steel ◽  
Microstructural Analysis ◽  
Welding Process ◽  
Fusion Welding ◽  
Tool Steels ◽  
Aisi D2 ◽  
Semi Solid ◽  
Aisi D2 Tool Steel ◽  
Microstructural Effect

Tool steels are commonly used to cut metal materials due to their distinctive hardness, resistance to abrasion and deformation. However, tool steels are difficult to be joined using conventional fusion welding process. In this study, a thixotropic property of metal was utilised to butt-join an AISI D2 tool steel by using uncommon direct partial re-melting (DPRM) method. A high frequency of induction heating is used to apply the DPRM method. From the recent study, there are many methods in achieving the globular microstructure with the success of semi-solid joining process. Though, very less information on the microstructural effect of semi-solid joining on the mechanical properties was reported. This study aims to analyse the effect of uniaxial force on the microstructural evolution and mechanical properties of the thixo-joint of D2 tool steel. The microstructural analysis showed the diffusion occurred between the grains of the thixo-joint sample with 2.5 N uniaxial force. The maximum strength of the thixo-joint sample with force was 652 MPa. This was slightly higher than the as-received sample and the thixo-joint sample without force. The average hardness value of the thixo-joint sample was 400 HV due to the transformation of ferrite to the metastable austenite.

scholarly journals Structure of MMCs with SiC Particles after Gas-tungsten Arc Welding

2015 ◽  
Vol 15 (4) ◽  
pp. 65-68 ◽  
Author(s):  
E. Przełożyńska ◽  
K.N. Braszczyńska-Malika ◽  
M. Mróz
Keyword(s):  
Fusion Zone ◽  
Arc Welding ◽  
Welding Process ◽  
Welding Current ◽  
Gta Welding ◽  
Magnesium Matrix ◽  
Gas Tungsten Arc ◽  
Sic Particles ◽  
Gtaw Process ◽  
Gas Tungsten

Abstract The gas-tungsten arc (GTA) welding behaviors of a magnesium matrix composite reinforced with SiC particles were examined in terms of microstructure characteristics and process efficiencies. This study focused on the effects of the GTAW process parameters (like welding current in the range of 100/200 A) on the size of the fusion zone (FZ). The analyses revealed the strong influence of the GTA welding process on the width and depth of the fusion zone and also on the refinement of the microstructure in the fusion zone. Additionally, the results of dendrite arm size (DAS) measurements were presented.

Effect of Vibratory Treatment on Hot Cracking Resistance in AA6061 Alloy

2012 ◽  
Vol 584 ◽  
pp. 516-520 ◽  
Author(s):  
Kaliyaperumal Balasubramanian ◽  
V. Balusamy
Keyword(s):  
Arc Welding ◽  
Welding Process ◽  
Hot Cracking ◽  
Fusion Welding ◽  
Test Results ◽  
Frequency Range ◽  
Alloy Specimen ◽  
Gas Tungsten Arc ◽  
Aa6061 Alloy ◽  
Cracking Tendency

AA6061 alloy is most widely used in aircraft fittings, marines fitting and automobile industries. This alloy can be joined by fusion welding process like Gas Tungsten Arc Welding (GTAW). An important metallurgical difficulty in arc welding of this alloy is hot cracking. As the name indicates, this kind of cracking occurs while the metal is still hot. It usually occurs in the fusion zone during solidification. The main aim of this work is to investigate the effect of vibratory treatment on hot cracking of AA6061 alloy. Houldcroft hot cracking test is used to determine the hot cracking tendency. Weld bead was made on AA6061 alloy specimen in the presence and absence of vibratory treatment. Vibratory treatment was carried out in the frequency range of 250 Hz to 900 Hz. Weldments made with and without vibratory treatment were compared using hot cracking tests. Test results show that by applying vibratory treatment, hot cracking can be largely controlled in AA6061 alloy.

INVESTIGATION OF PULSE FREQUENCY ON FUSION ZONE CHARACTERISTICS OF GTA WELDED AZ31B MAGNESIUM ALLOY JOINTS

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Subravel V
Keyword(s):  
Magnesium Alloy ◽  
Tensile Properties ◽  
Fusion Zone ◽  
Welding Speed ◽  
Pulse Frequency ◽  
Pulsed Current ◽  
Az31b Magnesium Alloy ◽  
Gas Tungsten Arc ◽  
Gas Tungsten ◽  
Different Levels

In this investigation an attempt has been made to study the effect of welding on fusion characteristics of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints. Five joints were fabricated using different levels of welding speed (105 mm/min –145 mm/min). From this investigation, it is found that the joints fabricated using a welding speed of 135 mm/min yielded superior tensile properties compared to other joints. The formation of finer grains and higher hardness in fusion zone and uniformly distributed precipitates are the main reasons for the higher tensile properties of these joints

scholarly journals Recommendations for an Open Science approach to welding process research data

2021 ◽  
Author(s):  
Cagtay Fabry ◽  
Andreas Pittner ◽  
Volker Hirthammer ◽  
Michael Rethmeier
Keyword(s):  
Domain Knowledge ◽  
Knowledge Exchange ◽  
Welding Process ◽  
Open Science ◽  
Research Data ◽  
Fusion Welding ◽  
File Format ◽  
Data Format ◽  
Science Practices ◽  
Science Community

AbstractThe increasing adoption of Open Science principles has been a prevalent topic in the welding science community over the last years. Providing access to welding knowledge in the form of complex and complete datasets in addition to peer-reviewed publications can be identified as an important step to promote knowledge exchange and cooperation. There exist previous efforts on building data models specifically for fusion welding applications; however, a common agreed upon implementation that is used by the community is still lacking. One proven approach in other domains has been the use of an openly accessible and agreed upon file and data format used for archiving and sharing domain knowledge in the form of experimental data. Going into a similar direction, the welding community faces particular practical, technical, and also ideological challenges that are discussed in this paper. Collaboratively building upon previous work with modern tools and platforms, the authors motivate, propose, and outline the use of a common file format specifically tailored to the needs of the welding research community as a complement to other already established Open Science practices. Successfully establishing a culture of openly accessible research data has the potential to significantly stimulate progress in welding research.

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