Aluminum Alloys Welding: A Review

International Journal on Future Revolution in Computer Science & Communication EngineeringVolume: 4 Issue: 1ISSN: 2454-4248153 – 159results show that the grains in SZ were greatly refined to 34 mm after FSP in both SS and AG alloys [4.].Friction stir welding of AA7075 alloy with the additionof boron carbide powder resulted in the improved hardnessand refinement of microstructure in nugget zone.Microstructure of nugget zone was found to be responsive tothe post weld heat treatments of peak-aging (T6),retrogression and RRA. Maximum value of hardness at therate of 67.25 Hv was observed at weld pitch of 0.050mm/rev. with 20 mm tool shoulder diameter [5].The bestquality weld was acquired using hexagon tool profile. Amathematical model was developed to predict the corrosionresistances of friction stir welded AA2219 aluminum alloyjoints with 95% of confidence level. The model wasdeveloped by incorporating the welding parameters and toolprofiles using statistical tools, such as design of experimentsand regression analysis [6].An Al–Zn–Mg–Cu, Al 7075,alloy was subjected to friction stir processing (FSP) usingseveral processing conditions, two different backing anvilsand three initial precipitation states in order to reach themaximum feasible processing severity to produce ultrafinegrain sizes. Microstructures formed by fine, equaled andhighly mis oriented grains were obtained [7].The micro hardness of the Al/B4C surface nanocomposites is higher in comparison with B4C microparticles. The presence of nano size B4C particlescontributes to produce ultrafine grain size. [8].The FSP ofcast Al-17% Si has been successfully performed withdesigned tool dimensions such as shank diameter 25 mm,shoulder diameter 18mm, pin diameter 8mm, pin length 3.5.The significant refinement of eutectic and coarse primary Siparticles and improved distribution of Si particles in the Almatrix takes place as a result of FSP in cast Al-17% Si alloy.[9].The values of the concentration of the reinforcing phaseare not the same in all of the tested areas and are subject tolarge fluctuations from about 8% in the nugget zone to about18% on the retreating side. The value of the anisotropycoefficient was not directly dependent on the concentrationof the reinforcing phase. The lowest values of the coefficientj were recorded for the nugget and the highest for TMAZ onthe retreating side [10].Submerge friction stir process iscapable of producing fine AA5083/Al2O3 nano-composite.In lower number of passes, some agglomerations were seenin the microstructure of the underwater friction stirprocessed sample; increasing the number of passes wassuccessful in re ducing the sea agglomerations to a moresatisfactory level. In air FSP,the difference between yieldstrength of the powder-less sample and the one withreinforcement phase is more than that for the correspondingsamples processed under water [11].During multi-pass FSP, accumulated plastic straincontinuously decreased the size and aspect ratio of Siparticles, while repeated thermal cycles introduced thenanoscale and ultrafine Si particles within the grain interior.Multiple strengthening mechanisms including loadtransferring, grain refinement, Orowan strengthening osites [12].After SFSP, coarse grain sand secondphases in a s-castMg–Y– Nd alloy are significantly refinedto 1.3 μm and 280 nm, respectively Particles in Mg–Y–Nd alloy are not the dominated factor for the stressconcentration during super plastic deformation; cavities areeasily formed at the grain boundaries instead of the interfacebetween particles and matrix. GBS a accommodated bylattice diffusion is the dominated de- formation mechanismduring super plastic deformation [13].A successful weldingis carried out between AISI 304 SS and pure Cu without anyfiller metal by CO2 laser having acceptable weld Strength ofabove 190 MPa. Hence, there is still scope for obtaining asmoother transition in microhardness values by controllingheat transfer rate and mode of welding [14].A significantly high tensile strength of 187.8 N/mm2,which is 91 % of that of the base material, was achieved athigh weld pitch of 0.05 mm/rev with tool shoulder diameterof 20 mm due to sufficient heat generation, proper grainrefinement and ductility. Grain size decreased with increasein weld pitch. Thus average grain diameter of 9.2 μm wasobserved at weld pitch of 0.050 mm/rev. with tool shoulderdiameter of 20 mm [15].Friction stir surfacing of as castA356 Aluminium alloy is able to refine the microstructureand form hard surface composite by reinforcing boroncarbide particles in the aluminium matrix. Friction stirsurfacing is an effective strategy to enhance the wearresistance of as cast A356 aluminum-silicon alloy to be usedfor high performance engineering Applications liketorpedoes in defense.[16].The three welded joints, the jointfabricated by FSW process exhibited higher strength values,and the enhancement in strength value is approximately13% due to grain refinement in SZ, unique weld metalcomposition and strain-induced deformation during FSW.The three joints, the joint fabricated using GMAW exhibited28% and 10% higher impact toughness, respectively,compared to the joints fabricated by FSWand SMAWprocesses. The presence of martensite-austenite (M-A)constituents and the ferrite laths in biotitic matrix in theweld zone microstructure are the key reasons forenhancement of toughness properties [17].While the micro- structure of the aluminum alloycomposed of a coarse-grained structure ( 50 mm) withelongated complex(Fe,Mn,Cr)3SiAl12 precipitate sandround Mg 2 Si particles , FSP refined the grain structuretoabout10 mm through a dynamic recrystalization processandrod-like precipitates of Al–Fe–Mn–Si besideoftheCr2and Mg2Si particles with respectively cuboidal andspherical shapes were formed [18].Compared with NFSP,SFSP has remarkable grain refinement effect. The averagegrain size of the NFSP and SFSP specimen is 8.4 } 1.3and 2.8 } 0.8 m, respectively. Furthermore, themicrostructures in the TMAZ and HAZ for the SFSP are155IJFRCSCE January 2018, Available @ http://www.ijfrcsce.org (ICATET 2018)

International Journal on Future Revolution in Computer Science & Communication EngineeringVolume: 4 Issue: 1ISSN: 2454-4248153 – 159much finer than those for the NFSP. After FSP, the coarsenetwork β-Mg17Al12 phases in the as-cast condition arechanged into particles pinned on the grain boundaries.[19].The unprocessed and processed welds had lowerhardness as well as lower yield and tensile strengths than thebase material. The grain refinement of the microstructureand the removal of MIG weld defects, achieved by thefriction stir processing; have the major contribution to theimprovement of fatigue resistance [20].The slow weldingspeed results in better fatigue performance. This is becausethe slow speed produces a highly refined, homogeneous anddefect free microstructure [21].The trend of age hardeningresponse in FSPed alloy is exactly similar than that of castalloy As compared to T6 treated cast alloy, the FSPed alloyafter peak ageing showed a significant increase in YS, UTSand ductility. The enhancement of mechanical propertiesmay be due to combined effect of precipitation hardening, orwan strengthening and grain boundary strengthen-ing [22].The tool pin profile and tool rotational speed are havinginfluence on tensile properties of the FSW joints. Out of twopin profile used to fabricate the joints, straight cylindricalpin profile exhibited superior tensile properties compared toother joints [23]. The shoulder diameter of FSW and heatinput during the welding process determines the width of thehardness. Higher performance in production rate andquality, as well as decreasing production costs, can beobtained by FSW welding. The required pre-operationsbefore the welding process are very limited in FSW. Thisfeature of the FSW process saves consumable material timecost and improves the quality of welds [24].The transverseshrinkage generated in GTAW weld joint is comparativelylower than that in GMAW weld joint. From the EDSanalysis, it is concluded that the use of GTAW processreduces the severity of weld thermal cycle in weld depositand HAZ region. X-ray Diffraction patterns revealed that Alis the major phases, and small amount of Al2Cu wasobserved [25].Post weld heat treatment of AA7075 alloy friction stirweld to Retrogression and reaging (RRA) treatment hadshown a good combination of high tensile strength andcorrosion resistance over as-welded and PWHT-T6 samples.The finer grains and continuous precipitates along the grainboundaries in T6 samples lead to high pitting corrosion[26].The use of low hydrogen ferritic steel consumables isfound to be beneficial to enhance the fatigue crack growthresistance of armour grade Q&T steel joints than the jointsfabricated by conventional ASS consumables [27].Frictionstir processing promotes fatigue resistance improvement,mainly due to microstructure grain refinement and theremoval of previous welding defects, such as porosity andlack of wetting. The stress concentration reduction, due totoe radius increase also contributes to fatigue lifeenhancement [28].Friction stir processing improves fatigue life ofreinforced and non- reinforced MIG welds. Thisimprovement was caused by geometric modification, grainrefinement and the removal of previous defects, such asporosity and lack of wetting [29].Tools with convexshoulder geometry allow the placement of the nugget on theMIG weld toe but cause weld defects such as cavities orreduction in plate thickness. Friction stir processing causessignificant grain refinement in the nugget in both alloysstudied and removes defects [30].The Tailor welded blank of AA2024 and AA7075,having a thickness ratio of 1.3 have been successfullybuttwelded using FS welding technique. The transformationof the plasticized material from the advancing side to theretreating side is uniform in all the elements .The weldstrength is lower as compared to the base metals, which isdue to the thickness ratio of the dissimilar welds beinggreater than unity [31].For a given FSW tool shoulderdiameter and parameters, the taper angle of the tapercylindrical (TC) tool pin and volume of tool pin penetrationin to steel have significant influence onthe thickness andcomposition of the inter metallic compound (IMC) layerformed and hence the joint performance. The FSW tool withTC pin profile having10 taper angle has produced the bestjoint with a joint tensile strength of 188MPa at a tool axisoffset of 2 mm towards Al alloy [32].Ferrite content in theweld metal of the AISI 304L joints when welded using heatinput in the range of 8.7 to 14.7 kJ/cm length of the weld,does not change significantly, but its morphology changesfrom lathy to vermicular as heat input is increased. Thisvariable degree of HAZ grain coarsening exerts a significantinfluence on the degree of carbide precipitation that occursinter granularly, when subjected to post-weld thermal agingtreatments [33].The highest joint strength of about 91% of the UTS ofthe base Al alloy is obtained at a tool traverse speed of 45mm/ min and both at higher and lower tool traverse speeds,the joint strengths are low. SEM and EDS quantitativeanalyses suggest that the inter metallic compound (IMC)layer formed at the joint interface are FeAl2 and FeAl3 andthe tensile strength of the joint greatly depends on thethickness of IMC layer formed at the joint interface [34].Thefracture toughness of the welded joint for a transition ofcrack from the copper side to the steel side is greater thanthe case in reverse. For the transition of the crack from theweaker copper to the stronger steel, the interface is positiveand increased as long as the crack tip positions are heldbefore and near the interface between copper and nickelweld. This is due to the shielding effect caused by theelastic–plastic mismatch coupled with the compressiveresidual stresses [35].In the FSW welding processes, thedecisive influence on the quality of the joint is exerted bythe process parameters such as the rotational speed, and therate of feed, the angle of inclination, and the profile anddimension of the stirring tool. A relatively wide range ofprocess parameters was found to produce qualitativelysatisfactory joints within the sets of the investigated materialcombinations. The main reason for the presence ofdiscontinuities in the region of the root of weld is theinsufficient depth of penetration of the mandrel into thewelded material [36].The allowable tolerance for the deterioration of thetransverse yield strength would vary depending on the156IJFRCSCE January 2018, Available @ http://www.ijfrcsce.org (ICATET 2018)

International Journal on Future Revolution in Computer Science & Communication EngineeringVolume: 4 Issue: 1ISSN: 2454-4248153 – 159application of the welded joint and the operatingenvironment therein. Fatigue testing was beyond the scopeof this study but it is likely the determination of thetolerances levels to tool centre line deviation would beinfluenced by fatigue [37].The strength values decreasedfrom weld metal to base metal. The A-GTAW joint weldmetal exhibited higher yield strength followed by SAW,FCAW and SMAW respectively. The HAZ of SMAW jointshowed higher YS followed by A-GTAW, FCAW and SAWrespectively. The volume fraction of polygonal ferrite wasobserved to be inversely proportional to the strength of weldmetal in the arc welded joints [38].Sound FSW weld joints were developed with andwithout in-process cooling. Following conclusion can bemade based on this investigation. The in-process coolingduring FSW of AA7039 extracts the excess process heatwhich in turn minimizes the extent of static grain growthinWNZ and coarsening in HAZ. Therefore, size of aaluminum grains in WNZ, TMAZ and HAZ wassignificantly lower than normal joints [39].Post weld heattreatments adversely affected yield strength (3.3–66.5%)more than the tensile strength (5.1–38.7%) of friction stirweld joints.The post weld heat treatment changed the fracturelocation from HAZ in as welded condition to TMAZ–HAZinterface for naturally and artificially aged joints, or WNZfor step aged and solution treated joints with and withoutartificial aging. Solution treated joint with and withoutartificial aging showed ductile–brittle mode of fracture[40].In the stirred zone, fine equi-axed grains of size rangingare transformed from the parent metal grain structure; Thetensile strength of welded joints can be increased using theFSW process compared MIG; Hardness change in thewelded material is affected by the amount of the heat inputduring the welding process; The heat-affected zone of FSWprocess is narrower than that of the MIG process. Higherheat intensity in the MIG process negatively affects of themechanical properties of the welded material [41].Figure 2 (a) Macro image of weld zone, (b) probe root area of interface, (c)middle area of interface, (d) probe tip area of interface, (e) SZ of AA6061T6, (f) BM of AA6061-T6, (g) BM of Ti-6Al-4V [36]V- MATERIALS AND ITS THICKNESSESTABLE III- THICKNESS OF VARIOUS MATERIALS USED INDIFFERENT PROCESSES 5262728293031323334353637383940Parent MaterialsHSLA SteelAl-5083Al-7 B04Mg- 7.88Gd-4.28Y-1.1Nd-0.45ZrAA7075AA2219Al 7075Al5083Al17%SIIgnotCopper Al PolymerA356Cast Mg–4.27Y–2.94Nd–0.51ZrAISI 304AZIB-OmgA356HSLA SteelAA5052AZ916082-T651DH36 SteelCast IngotAA6061AA6061AA2219AA7075AISI 43405083-H111AA6082-T65083-H111 & 6082-T651AA2024 T3AA 5052AISI 304LAA5052En31Al1000,Al5000,Copper M1EDH36HSLA SteelAA7039AA7039 T6Thickness5 mm.3.5 mm2 mm6 mm.8 mm.7 mm.3 mm.8 mm6 mm4 mm.6 mm.6 mm.6 mm.3 mm.5 mm.50 mm.5 mm.5 mm.6 mm.6 mm.6 mm.8 mm.6 mm.9.5 mm.25 mm.8 mm14 mm.6 mm.6 mm.6 mm.5 mm.3 mm.6 mm.3 mm.10 mm.4 mm.6 mm.10 mm.5 mm.5 mm.VI- CONCLUSIONAlloying elements are selected based on their effect andSuitability. The present review has demonstrated theextensive research effort that continues to progress theunderstanding of FSW of aluminum alloys and its influence157IJFRCSCE January 2018, Available @ http://www.ijfrcsce.org (ICATET 2018)

International Journal on Future Revolution in Computer Science & Communication EngineeringVolume: 4 Issue: 1ISSN: 2454-4248153 – 159on their microstructure and properties. It identifies a numberof areas that are worthwhile for further study. From anengineering perspective, there is a need to investigate theoccurrence and significance of flaws in friction stir welds. Inparticular, the influence of tool design on flaw occurrenceand the development of nondestructive testing techniques toidentify flaws in both lap and butt welds would bebeneficial. Metal flow modeling may have a role to playhere; though capturing this aspect of the thermo mechanicalbehavior remains a significant challenge.There are vastareas as applications of aluminum alloys in India withworldwide. The different processes of engineering andwelding technology with friction stir processing arevaluable, effective and 7][8][9][10]R. S. Rana, Rajesh Purohit, and S Das, reviews on theinfluences of alloying elements on the microstructure andmechanical properties of aluminum alloys composites ,International Journal of Scientific and ResearchPublications ; 2012 ; Volume 2, Issue 6; 1-7Yu Chen , Hua Ding , Jizhong Li , ZhihuiCai , JingweiZhao , Wenjing Yang , Influence of multi-pass friction stirprocessing on the microstructure and mechanical propertiesof Al-5083 alloy, Material Science & Engineering ;2016;650(A) ;281-289.YuChen, HuaDing, ZhihuiCai, JingweiZhao, JizhongLi,Effect of initial base metal temper on microstructure andmechanical properties of friction stir processed Al-7B04alloy ; Material Science & Engineering ; 2016;650(A) ;396403.P. L. Threadgill., Terminology in friction stir welding,Science and Technology of Welding and Joining, Vol 12 ,No 4, 2007, 357- 360.RenlongXin, XuanZheng , Zhe Liu , Dejia Liu ,RishengQiu, Zeyao Li, Qing Liu , Microstructure andtexture evolution of an Mg-Gd-Y-Nd-Zr alloy duringfriction stir processing, Journal of Alloys andCompounds;2016; 659;51-59.G. Rambabu, D. BalajiNaik, C.H. VenkataRao K.SrinivasaRao,G. Madhusudhan Reddy , Optimization offriction stir welding parameters for improved corrosionresistance of AA2219 aluminum alloy joints ,A. Orozco-Caballero , P. Hidalgo-Manrique , C.M. CepedaJiménez , P. Rey , D. Verdera , O.A. Ruanoa, F. Carreño,Strategy for severe friction stir processing to obtain acutegrain refinement of an Al–Zn–Mg–Cu alloy in three initialprecipitation states,Materials Characterization indanb,,Vipin,Fabrication of Al5083/B4C surface composite by frictionstir processing and its tribological characterization, j m a t er r e s t e c h n o l . 2 0 1 5;4(4):398–410.N. Saini, D.K. Dwivedi, P.K. Jain, H. Singh, SurfaceModification of Cast Al-17%Si Alloys using Friction StirProcessing,2015; Procedia Engineering 100 ; 1522 – Wójcicka, Adam Pietras , Cast aluminium es modified with using FSP process – Changing ofthe structure and mechanical properties , CompositeStructures ;2015;133; 959–967.M. Ashjari , A.MostafapourAsl , S.Rouhi , Experimentalinvestigation on the effect of process environment on themechanical properties of AA5083/Al2O3 nano compositefabricated via friction stir processing , Materials andDesign;2015; 85 ;626–634.Rui Yang ,Zhenya Zhang, Yutao Zhao, Gang Chen,YuhangGuo , Manping Liu ,Jing Zhang, Effect of multipass friction stir processing on microstructure andmechanical properties of Al3Ti/A356 composites, MaterialsCharacterization ;2015;106 ; 62–69.Genghua Cao, Datong Zhang , Fang Chai, Weiwen Zhang,Cheng Qiu, Super plastic behavior and microstructureevolution of a fine-grained Mg–Y–Nd alloy processed &Engineering;2015;A (642); 157–166.BikashRanjanMoharana, Sushanta Kumar Sahu , SusantaKumar Sahoo, Ravi Bathe, Experimental investigation onmechanical and microstructural properties of AISI 304 toCu joints by CO2 laser, Engineering Science andTechnology, an International Journal (2015), doi:10.1016/j.jestch.2015.10.004Inderjeet Singh, Gurmeet Singh Cheema, Amardeep SinghKang , An experimental approach to study the effect ofwelding parameters on similar friction stir welded joints ofAZ31B-O Mg alloy ,R. Srinivasu, A. SambasivaRao , G. Madhusudan Reddy ,K. SrinivasaRao, Friction stir surfacing of cast A356aluminium-silicon alloy with boron carbide andmolybdenum disulphide powders, 2015 DefenseTechnology 11 :140-146.S. Raghunathan, V.Balasubramanian S. Malarvizhi, A.G.Rao , Effect of welding processes on mechanical andmicrostructural , Characteristics of high strength low alloynaval grade steel joints. DefenceTechnology ;2015;11 ;308317.F.Khodabakhshi, A.

Mar 02, 2018 · Aluminum alloys since the technique was invented in 1991 is reviewed on this paper. The basic principles of FSW are described, including the applications of aluminum alloys and material thickness used in different . I-INTRODUCTION Aluminum and aluminum alloy are gaining huge . and O tempers