scholarly journals Microstructure Characteristics and Its Effect on the Fracture in the Triple Junction Region of Friction Stir Welded Mg Alloys Subjected to Tension

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3672
Author(s):  
Guodong Liu ◽  
Qunying Yang ◽  
Yongshan Cheng
Keyword(s):  
Triple Junction ◽  
Weld Zone ◽  
Base Material ◽  
Junction Region ◽  
Friction Stir ◽  
Microstructure Characteristics ◽  
Transverse Tension ◽  
Twin Band ◽  
Zone Edge ◽  
Electron Back Scattered Diffraction

Because of the tensile strength decreasing of the friction stir welded wrought magnesium (Mg) alloy compared to the base material, the reasons for the failure of weld has been focused on. After the fracture in transverse tension, the crack went through the welded joint from the center of the weld to the transition zone between the thermal-mechanical affected zone and weld zone. In the present study, the microstructure characteristics and its effect on the facture in the triple junction region is investigated. Based on the metallography and the electron back-scattered diffraction (EBSD) technology, it was observed that a twin band extended from the triple junction region to the middle of weld. The profuse twinning in the twin band was considered to play an important role on the crack propagation from the stir zone edge to the crown zone.

scholarly journals Mechanical and Microstructural Characterization of Friction Stir Welded SiC and B4C Reinforced Aluminium Alloy AA6061 Metal Matrix Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3110
Author(s):  
Kaveripakkam Suban Ashraff Ali ◽  
Vinayagam Mohanavel ◽  
Subbiah Arungalai Vendan ◽  
Manickam Ravichandran ◽  
Anshul Yadav ◽  
...  
Keyword(s):  
Wear Rate ◽  
Aluminium Alloy ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Weld Zone ◽  
Base Material ◽  
Matrix Composites ◽  
Wear Properties ◽  
Friction Stir ◽  
Behavioural Aspects

This study focuses on the properties and process parameters dictating behavioural aspects of friction stir welded Aluminium Alloy AA6061 metal matrix composites reinforced with varying percentages of SiC and B4C. The joint properties in terms of mechanical strength, microstructural integrity and quality were examined. The weld reveals grain refinement and uniform distribution of reinforced particles in the joint region leading to improved strength compared to other joints of varying base material compositions. The tensile properties of the friction stir welded Al-MMCs improved after reinforcement with SiC and B4C. The maximum ultimate tensile stress was around 172.8 ± 1.9 MPa for composite with 10% SiC and 3% B4C reinforcement. The percentage elongation decreased as the percentage of SiC decreases and B4C increases. The hardness of the Al-MMCs improved considerably by adding reinforcement and subsequent thermal action during the FSW process, indicating an optimal increase as it eliminates brittleness. It was seen that higher SiC content contributes to higher strength, improved wear properties and hardness. The wear rate was as high as 12 ± 0.9 g/s for 10% SiC reinforcement and 30 N load. The wear rate reduced for lower values of load and increased with B4C reinforcement. The microstructural examination at the joints reveals the flow of plasticized metal from advancing to the retreating side. The formation of onion rings in the weld zone was due to the cylindrical FSW rotating tool material impression during the stirring action. Alterations in chemical properties are negligible, thereby retaining the original characteristics of the materials post welding. No major cracks or pores were observed during the non-destructive testing process that established good quality of the weld. The results are indicated improvement in mechanical and microstructural properties of the weld.

scholarly journals Influence of Mx-Trivex, A-Skew, Three Flat Threaded and Concave Shouldered Mx-Triflute Tool Pin Profiles on Tensile Properties and Fractural Behaviour of Aa 6082-T6 Weldments During Friction Stir Welding

2020 ◽  
Vol 9 (4) ◽  
pp. 1376-1384
Keyword(s):  
Friction Stir Welding ◽  
Tensile Test ◽  
Weld Zone ◽  
Base Material ◽  
Traverse Speed ◽  
Friction Stir ◽  
Tool Pin ◽  
Solid State Joining ◽  
Joining Process ◽  
Brass Wire

Friction Stir Welding (FSW) is a topical and propitious solid-state joining process producing economical and strengthened joints of age-hardened and heat-treatable Aluminium Alloy AA 6082-T6. Mechanical and fractural behaviour of weldments were investigated in order to find crack initiation and necking on the weld zone thereby perceiving the complete behaviour of fracture occurred near the weld zone. Weldments are fabricated by employing four tool pin profiles namely MX-TRIVEX, A-SKEW, Three flat threaded and Concave shouldered MX-TRIFLUTE tools at various rotational speeds 1000 rpm, 1200 rpm and 1400 rpm at single traverse speed 25 mm/min. EXCETEX-EX-40 CNC wire cut EDM with 0.25 mm brass wire diameter has been employed to perform the extraction of tensile test specimens from the weldments according to ASTM E8M-04 standard. Tensile test was performed on elctromechanically servo controlled TUE-C-200 (UTM machine) according to ASTM B557-16 standards Maximum Ultimate Tensile Strength (UTS) of 172.33 MPa (55.5% of base material) and 0.2% Yield Stress (YS) of 134.10 MPa (51.5% of base material) were obtained by using A-SKEW at 1400 rpm, 25 mm/min and maximum % Elongation (%El) of 11.33 (113.3% of base material) was obtained at MX-TRIVEX at 1000 rpm, 25 mm/min. Minimum UTS of 131.16 MPa (42.30% of base material) and 0.2% YS of 105.207 MPa (40.46% of base material )were obtained by using Concave shouldered MX-TRIFLUTE at 1400 rpm, 25 mm/min. Minimum % El of 5.42 ( 54.2% of base material) was obtained by using A-SKEW at 1000 rpm, 25 mm/min.

Nonuniformity of Mechanical Property in the Weld Zone of Friction Stir Welded 7050 Aluminum Alloy Joint

2011 ◽  
Vol 189-193 ◽  
pp. 3560-3563
Author(s):  
Yu Wen Tian ◽  
Fei Xu ◽  
Wen Ya Li ◽  
Zhong Bin Tang
Keyword(s):  
Mechanical Property ◽  
Aluminum Alloy ◽  
Elastic Modulus ◽  
Weld Zone ◽  
Base Material ◽  
Weld Nugget ◽  
Second Phase ◽  
Nugget Zone ◽  
Friction Stir ◽  
7050 Aluminum Alloy

The distribution of mechanical property in the weld zone of friction stir welded 7050 aluminum alloy joint along the plane perpendicular to the welding direction was experimentally investigated by the non-contact measurement method. The results show that the elastic modulus presents a W-shape distribution across the weld zone. The elastic modulus in the weld nugget zone is increased due to the grain refinement. In addition, the elastic modulus in the advancing side is slightly less than that in the retreating side possibly because of the relatively higher temperature in the advancing side during the welding process. The strength in the vicinity of weld center is decreased while the ductility is enhanced. The tensile strength and yield strength in the weld nugget zone and thermo-mechanically affected zone are significantly decreased while the elongation is increased due to the change of strengthening mechanism. In the heat affected zone the strength is decreased compared to the base material because the second phase grows up.

Effect of Traverse Speed on the Microstructure and Mechanical Properties in Friction Stir Welded Dissimilar Barrier Butt Joints of AA2024 to AA6061/SiC/55p Composite

2014 ◽  
Vol 936 ◽  
pp. 1735-1741
Author(s):  
Xue Cheng Song ◽  
Li Jie Guo ◽  
Xiao Song Feng ◽  
Yu Huan Yin ◽  
Fan Cui
Keyword(s):  
Weld Zone ◽  
Base Material ◽  
Traverse Speed ◽  
Interface Bonding ◽  
Butt Joints ◽  
Interface Zone ◽  
Friction Stir ◽  
Joint Microstructure ◽  
Base Materials ◽  
Stirring Effect

Dissimilar barrier butt joints of AA2024 to AA6061/SiC/55p composite were fabricated by friction stir welding. Effect of the traverse speed on interface bonding, joint microstructure and tensile properties was investigated. Results revealed that, all joints possessed a tensile strength stronger than 80% that of the composite base materials, and the highest strength value was 178MPa. Macro interface can be readily identified in the weld zone between AA2024 and AA6061/SiC/55p composite, of which the area decreased and then increased as the traverse speed increased. The size and shape of SiC particles in the interface zone varied a lot due to different stirring effect and forward impact of the pin in different traverse speeds. Increasingly impairment of the composite base material near the interface was also detected with the traverse speed increasing.

Microstructure Characteristics and Properties of 1561 Aluminum Alloy Weldments Processed by Different MIG Welding

2017 ◽  
Vol 893 ◽  
pp. 163-168
Author(s):  
Shan Guo Han ◽  
Shi Da Zheng ◽  
De Tao Cai ◽  
Yao Yong Yi ◽  
Zi Yi Luo
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Weld Zone ◽  
Base Material ◽  
Particle Phase ◽  
Mig Welding ◽  
Single Wire ◽  
Microstructure Characteristics ◽  
Different Characteristics ◽  
Scanning Electron

The mechanical properties and microstructural features of 1561 aluminum alloy weldments processed by single-wire MIG welding and CMT TWIN welding are investigated. The microstructure and mechanical properties of welded joints were studied by nondestructive testing, metallurgical test, scanning electron microscopy test, fatigue and tensile test. It is revealed that the welding efficiency of CMT TWIN welding is more than six times as much as single-wire MIG welding. It can be easy to find weld zone (WZ), fusion line (FL), heat affected zone (HAZ) and base metal (BM) with different characteristics in the metallographic specimen. In weld zone, the particle phase sizes are smaller than that of base material, but the densities of particle phase are increased. The sample fatigue strength of CMT TWIN welding is higher than the singe-wire MIG welding. It is suggested that the CMT TWIN welding has several advantages compared with single-wire MIG welding.

Properties of Friction-Stir Welded Aluminum Alloys 6111 and 5083

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
W. Gan ◽  
K. Okamoto ◽  
S. Hirano ◽  
K. Chung ◽  
C. Kim ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Weld Zone ◽  
Base Material ◽  
Natural Aging ◽  
Tensile Tests ◽  
Travel Speed ◽  
Minimum Phase ◽  
Friction Stir ◽  
Base Materials ◽  
Fsw Parameters

Friction-stir welding (FSW) promises joints with low porosity, fine microstructures, minimum phase transformation, and low oxidation compared with conventional welding techniques. It is capable of joining combinations of alloys not amenable to conventional welding. Certain combinations of FSW parameters were used to create FSWs of aluminum alloys 5083-H18 and 6111-T4, and the physical weld defects were measured. The mechanical behavior of FSW welds made under the most favorable choice of parameters was determined using tensile tests and hardness measurements and was correlated to the microstructures of the weld and base material. Stir zones (SZs) in the 5083 specimens were much softer than the strain-hardened base materials. SZs in the 6111 material are approximately as hard as the base material. Natural aging of 6111 FSW specimens occurred in some parts of the heat-affected zone and produced hardening for up to 12weeks after welding. Annealing of 5083 FSW specimens produced abnormal grain growth (AGG) for welds produced under certain welding conditions and in certain parts of the weld zone. AGG is more severe for low-heat conditions, i.e., higher tool travel speed but lower rotational speed. The conditions for most favorable FSW are presented, as well as the expected microstructures and mechanical properties, along with the weld conditions that promote AGG.

Friction Stir Welding of Al-Li AA2199: Parameters, Precipitates and Post Weld Heat Treatment

2011 ◽  
Vol 409 ◽  
pp. 853-858
Author(s):  
Rosen Ivanov ◽  
Julien Boselli ◽  
Diana Denzer ◽  
Daniel Larouche ◽  
Raynald Gauvin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Friction Stir Welding ◽  
Weld Zone ◽  
Base Material ◽  
Post Weld Heat Treatment ◽  
Second Phase ◽  
Friction Stir ◽  
Tool Rotation ◽  
Weld Heat

The aerospace industry strives to develop materials allowing an increase in payload and reducing fuel consumption. Al-Li alloys, with their low density and high strength are currently in use for such applications and have potential for additional applications. When compared to composites, utilizing Al-Li alloy products is cost effective for aerospace companies as they do not need to redesign pre-existing fabrication facilities. The joining of these alloys by conventional methods is limited by segregation of alloying elements and the formation of oxides during high temperature exposure. This study focuses on solid state joining method that has the potential to generate low heat and be defect free - Friction Stir Welding (FSW). AA2199 sheets were joined by FSW. Process variables included table force, tool rotation speed and weld travel speed. A post weld heat treatment (PWHT) was applied to improve the mechanical properties by precipitation of strengthening phases. An increase in hardness of the weld zone from 95HV to 125HV upon PWHT was recorded for selected welding conditions. The type and morphology of second phase precipitates is deemed responsible for this effect. It is suggested that the high temperature and high strain levels characteristic of welds with fast tool rotation allow for the dissolution of precipitates during welding. The re-precipitation of these second phases during PWHT allowed the welds to recover strength to the level of the base material.

Textural variation in triple junction region of friction stir welded Mg alloys and its influence on twinning and fracture

2016 ◽  
Vol 658 ◽  
pp. 185-191 ◽  
Author(s):  
Zhe Liu ◽  
Renlong Xin ◽  
Dejia Liu ◽  
Xiaogang Shu ◽  
Qing Liu
Keyword(s):  
Triple Junction ◽  
Mg Alloys ◽  
Junction Region ◽  
Friction Stir

Experimental Investigation of Double Side Friction Stir Welding (FSW) on High Density Polyethylene Blanks

2010 ◽  
Author(s):  
S. Saeedy ◽  
M. K. Besharati Givi
Keyword(s):  
Friction Stir Welding ◽  
Weld Zone ◽  
Base Material ◽  
Material Strength ◽  
Welding Condition ◽  
Friction Stir ◽  
Factorial Method ◽  
Tool Tilt Angle ◽  
Crystallinity Changes ◽  
Side Friction

The effect of double side technique in friction stir welding of polyethylene blanks has been studied. Experiments have been designed and analyzed with the full factorial method. The process parameters were rotation speed and tool tilt angle. The optimum welding condition has been determined. It has been demonstrated that double side FSW can improve the weld quality by decreasing the problem of stress concentration in the root of the joint. By applying this technique, 80% of the base material strength is achieved. Considerable reduction in elongation and toughness of the seam weld is due to crystallinity changes of the weld zone which are indicated in the DSC test results.

High-Frequency Induction Assisted Hybrid Friction Stir Welding of Inconel 718 Plates

2021 ◽  
pp. 1-36
Author(s):  
Sanjay Raj ◽  
Pankaj Biswas
Keyword(s):  
Friction Stir Welding ◽  
Tool Life ◽  
High Frequency ◽  
Inconel 718 ◽  
Weld Zone ◽  
Base Material ◽  
Frictional Heat ◽  
Weld Strength ◽  
Friction Stir ◽  
High Frequency Induction

Abstract The preheating system is a promising approach to decrease the axial load, improve the weld quality, and enhance the tool life during the friction stir welding of high strength material. In the present work, conventional friction stir welding (FSW) and high-frequency induction heating-assisted friction stir welding (I-FSW) systems were used to join 3 mm thick Inconel 718 plates with a WC-10%Co tool and studied their performances. The welding was carried out at a constant rotational speed of 300 rpm, including varying traverse speeds of 90 mm/min and 140 mm/min and varying preheating temperatures (310 oC, 410 oC, and 700 oC). The results show that good weld joints were possible at high traverse speed (i.e., 140 mm/min) using the I-FSW at low preheating temperature (i.e., 310 oC). Grain refinement in the weld zone with and without preheated FSW led to improved mechanical properties. The increased size of intermetallic phases and carbide particles due to induction preheating in I-FSW were most likely to be responsible for the enhancement of the weld strength. The hardness of the stir zone was increased from 250 HV to 370 HV, and the ultimate tensile strength of the I-FSW joint reaches 740 MPa, which was 98.8 % of the base material. The results also revealed that preheating affected the process temperature results lowering the axial force and frictional heat, which improved the tool life.

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