scholarly journals Effect of Skewness during Friction Stir Welding of Dissimilar Aluminium Alloys EN AA 5083-H116 and EN AA 6082-T6 Including Fracture Observations

The corrosive resistant aluminium-magnesium alloy AA 5083-H116 and aluminium-silicon alloy AA 6082-T6 is widely used in ship building, marine and various structural applications. FSW is an emerging solid state joining process suitable for joining the aluminium alloys with minimized formation of weld defects like cracks, porosity etc. compared to other fusion welding processes. This research work presents FSW of EN AA 5083-H116 and EN AA 6082-T6 using skew tool pin profile with the consideration of influential process parameters like tool rotational speed of 710 and 900 rpm at constant traverse speed of 16 mm/min. Radiographic inspection has been performed for evaluating the weldments soundness. From the radiographic results it has been found that at higher rpm i.e at 900 rpm the occurrence of lack of fusion is more compared to the weldment fabricated at 710 rpm. Tensile properties and fractural observations were carried out on the weldments. It has been noted that good mechanical properties were observed with the weldment fabricated at 710 rpm with high tensile strength of 160 MPa. From the fractural observations it has been observed that all the specimens are prone to ductile fracture, besides shear lips were observed at specimens fabricated at 900 rpm.

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.


2011 ◽  
Vol 415-417 ◽  
pp. 1140-1146 ◽  
Author(s):  
R. Palanivel ◽  
P. Koshy Mathews ◽  
M. Balakrishnan ◽  
I. Dinaharan ◽  
N. Murugan

Aluminium alloys generally has low weldability by traditional fusion welding process. The development of the Friction Stir Welding (FSW) has provided an alternative improved way of producing aluminium joints, in a faster and reliable manner. FSW process has several advantages, in particular the possibility to weld dissimilar aluminium alloys. This study focuses on the behavior of tensile strength of dissimilar joints of AA6351-T6 alloy to AA5083-H111 alloy produced by friction stir welding was analysed. Five different tool pin profile such as Straight Square (SS), Tapered Square (TS), Straight Hexagon (SH), Straight Octagon (SO) and Tapered Octagon (TO) with three different axial force (1tonne, 1.5tonne, 2 tonne) have been used to weld the joints. The effect of pin profiles and axial force on tensile properties and material flow behaviour of the joint was analyzed and it was found that the straight square pin profile with 1.5 tonne produced better tensile strength then other tool pin profile and axial force.


2010 ◽  
Vol 297-301 ◽  
pp. 221-226 ◽  
Author(s):  
R. Salekrostam ◽  
M.K. Besharati Givi ◽  
P. Asadi ◽  
P. Bahemmat

Compared to the many fusion welding processes that are routinely used for joining stainless steel 316L, the friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and is being recast. The welding parameters play a major role in deciding the weld quality. In this investigation an attempt has been made to understand the influences of rotational speed and traverse speed of the tool on the microstructure of the friction stir processing zone in stainless steel 316L. Five different tool rotational speeds have been used to fabricate the joints at four different traverse speeds from this investigation which is the optimum for the tool speed and higher or lower amounts of these parameters are not useful for the process.


2020 ◽  
Vol 8 (6) ◽  
pp. 3514-3518

In the present research work, an attempt was made to evaluate the weld hardness profile on the weldments along the weld traverse direction fabricated using various tool pin probes (Concave triangular threaded probe, Inner rake angle probe, Flats on edges of probe and Scroll threaded flute probe) at three different rotational speeds 1000 rpm, 1200 rpm, 1400 rpm at single weld traverse speed 25 mm/min. Hardness profiles are useful for establishing interpretation on microstructure and weld mechanical properties, micro hardness was performed in order to outline the weld hardness profile in the vicinity of weld affected areas like Nugget zone, Thermo-mechanically affected zone, Heat affected zone and Boundary zone in the weldments. From the hardness profiles it was found that higher hardness value of 106 VHN1kg (Vicker’s Hardness Number at 1kg load) was obtained with the weldment fabricated using Scroll threaded flute probe at 1400 rpm and 25 mm/min i.e 15 mm distance away from the weld centreline on the advancing side of the weldment , besides lower hardness value of 49.8VHN1kg was obtained with weldment fabricated using concave triangular threaded probe at 1200 rpm and 25 mm/min at nugget zone i.e at the centerline of the weldment.


2014 ◽  
Vol 891-892 ◽  
pp. 1463-1468
Author(s):  
János Lukács ◽  
Ákos Meilinger

The friction stir welding (FSW) is a dynamically developing version of the pressure welding processes. Nowadays, the knowing of the properties and the behaviour of the welded joints is an important direction of the investigations, especially under cyclic loading. The research work aimed (i) to demonstrate the behaviour of the friction stir welded joints under cyclic loading conditions; (ii) to determine fatigue limit or design curves for aluminium alloys and their welded joints made by FSW process. Experiments were performed on 5754-H22 and 6082-T6 aluminium alloys and their welded joints. Both high cycle fatigue (HCF) and fatigue crack propagation (FCG) tests were executed on both base materials and their welded joints. Statistical behaviour of the base materials and welded joints was represented by the cutting of the specimens and the using of different crack paths. HCF limit curves were determined based on staircase method. FCG limit curves can be determined by own developed six step method. The investigations and their results were compared with each other and with the results can be found in the literature.


2018 ◽  
Vol 178 ◽  
pp. 03002 ◽  
Author(s):  
Marius Adrian Constantin ◽  
Ana Boşneag ◽  
Eduard Niţu ◽  
Monica Iordache

Welding copper and its alloys is usually difficult to achieve by conventional fusion welding processes because of high thermal diffusivity of copper, which is at least 10 times higher than most steel alloys. In order to reduce the increased temperature loss, it would be advantageous to use a process that is carried out at lower temperatures. Friction Stir Welding (FSW) is a solid state joining process that involves the joining of two metal pieces at the molecular level without melting and was explored as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (TIG - tungsten inert gas) which generates and adds heat to the process. The research includes two experiments for the FSW process and two experiments for TIG assisted FSW process. It is presented the evolution of the temperature and of the axial force during the process and is determined the microhardness for each experimental case. The aim of this paper is to make known the effects of using TIG assisted FSW process on the microhardness of the pure copper joints and to present some conditions in which it is less affected.


2018 ◽  
Vol 81 (1) ◽  
Author(s):  
Nor Fazilah Mohd Selamat ◽  
Amir Hossein Baghdadi ◽  
Zainuddin Sajuri ◽  
Amir Hossein Kokabi

Friction stir welding (FSW) is a gateway for the implementation of a solid state joining method between two lightweight materials especially aluminium alloys. Dissimilar joints of aluminium alloys have an issue to be weld using the conventional fusion welding. In the present work, two types of dissimilar joints of aluminium alloys were welded as dissimilar butt joints using the FSW method. 5mm thick base metals, consist of AA1100, AA5083 and AA6061, were butt welded to dissimilar joints of AA6061-AA1100 and AA6061-AA5083. Similar welding parameter was used for both of the joints, in which 100 mm/min and 1000 rpm for transverse and rotation speed, respectively. Joints were successful with defect-free internally and externally. However, different flow patterns were observed in the stirred zone due to the different materials flow during the FSW process. The ultimate tensile strength of AA6061-AA1100 and AA6061-AA5083 are 93MPA and 113MPa. Thereby, the joint efficiency of AA6061-AA1100 and AA6061-AA5083 were 80% and 97% compared to AA6061 base metal, respectively.


2014 ◽  
Vol 592-594 ◽  
pp. 216-223
Author(s):  
Nallavelli Ramesh ◽  
K. Palaksha Reddy

Aluminum alloys are mostly used for high strength structural applications utilized in aircraft structure, trucks body, military vehicles, bridges and weapons manufacture. Conventional fusion welding of aluminum alloy produces porosity and hot cracks in the welded joint due to incorrect selection of consumables and parameters, which may lead to lower weld toughness and defects in the mechanical properties. The mostly adopted method for welding AA 2014-T6 is solid state joining process. Friction stir welding (FSW) is an emerging solid state of joining process which avoids bulk melting of the basic material, hot cracking and porosity. The welding parameters and tool pin profile play a major role in deciding weld quality. In this investigation, an attempt has been made to understand the various influences of tool rotational speed, welding speed and pin profile of the tool on friction stir processed (FSP) zone formation in joining of AA2014 aluminum alloy. High Carbon High Chromium steel tool of plain cylindrical pin profile is used to fabricate the joints. The average grey relation grade for each level of each factor are calculated and it was found that the optimal settings of the levels of factors Tool rotation speed (A), Weld speed (B) and Tilt angle (C) are A1-B3-C3. The findings from these investigations will be presented and discussed.


In the bringout research work carried out the comparative study of weld characteristics of Aluminium Alloy AA2014-T6 weldments, joined by employing two processes namely Friction Stir Welding (FSW) and Gas Tungsten Arc Welding (GTAW). FSW was performed with three different geometrical tool pin profiles like triangular, square, pentagon with process variables like tool rotational speed of 1400rpm, traverse speed of 86mm/min and tool tilt angle 3⁰. GTAW process was carried out by using constant current welding (CCW) and pulse current welding (PCW) at a frequencies of 2Hz and 4Hz respectively. This work lead to study the Ultimate Tensile Strength (UTS), 0.2%Yield Strength (YS) and % Elongation (%El) of AA2014-T6 weldments produced by FSW and GTAW


2010 ◽  
Vol 638-642 ◽  
pp. 1221-1226 ◽  
Author(s):  
A.A.M. da Silva ◽  
E. Aldanondo ◽  
P. Alvarez ◽  
A. Lizarralde ◽  
A. Echeverria

Friction Stir Welding (FSW) is a solid-state joining process whereby no bulk melting of the base material occurs during joining. FSW avoids severe distortion and formation of as-cast coarse microstructure as well as defects arising from melting and solidification during traditional fusion welding processes. The objective of this investigation is to evaluate the effect of joining parameters on the mechanical and microstructural properties of dissimilar aluminium alloys (3 mm thick AA2024-T3 and AA7075-T6 sheets) joints produced by FSW. Microstructural features have been analysed; while mechanical performance has been investigated in terms of hardness and tensile testing. In both welding configurations the boundary between the base materials at the stir zone is clearly delineated, i.e., no material mixing is observed.


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