Cladding of Advanced Al Alloys Employing Friction Stir Welding

Clad

1_M 2_Engineeri Keywords alloy, AA10 Abstract. presented. coating us AA1050 fi discussed. substrate o analyzed u resulting m Introducti Friction sti no solidific alloyed aer with a thin requires re material. T restoration to enhance In t that is rela hollow too literature [ authors. Th substrate s technique cylindrical central pin

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Materials inn ing Techno a_a.vande s: Friction s 050 alumini In this pape The Frictio sing filler m iller materia Depending or mixed th using SEM-microstructu ion ir welding cation-relat rospace alu n layer of pu emoval of th This leaves t n of the clad e the life exp

this paper a ated to FSW ol. The con [4, 5], but he cladding surface and [6, 7]. A s l channels t n. F

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(FSW) is a ed joint imp uminium gra ure aluminiu he clad layer the welded d layer is re pectancy of a solid state W [1 - 3] a ncept of a no results h process com d (ii) the de specially de that contain Figure 1. Sch

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stitute (M2i), rsity of Twe .nl, b_t.c.bor@ dding, fricti nced solid st Cladding (F n a substrat ted on a rel rocess cond surface reg cal microsc blish the de relatively n perfections ades, like A um for corr r prior to w region vuln quired to re f the welded e cladding nd allows d hollow FS have been mbines (i) t eposition of esigned FSW n the filler m hematic repre

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2 GA Delft, the 0 AE Ensch ijselaers@u on surfacing based on Fr les the depo rgical bond T351 substr erial is dep The cladde ess measure g technolog st suitable fo x. These all ion stir wel kening of th fter the joini ction of the face Claddi d layers on scribed bef to the curr e to friction ar to the Fr ut a central r an examp face cladding

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nds Netherlands aluminium Welding, is a solid-state atively soft e results are top of the regions are identify the ls. It shows weld highly ten cladded ch materials he soft clad . Post-weld and as such s presented e through a y in patent edge of the ng tool on a facing (FS) ovided with ol without a m s e t e e e e s y d s d d h d a t e a ) h a

During the cladding m be restored In t substrate m Friction S The presen both proce consumabl differences consumabl cylindrical axis and ca the lateral clad layer softening a but, if the between th contributio Figu The design the force e different re flash forma tool should efficient us with a cent application Experimen The experi powered F region of t used to de include too bottom on exerted on substrate b e process th material that d locally and this work th material has urface Cla nted friction esses add a c le rods wh s. Firstly, f le rods of e l rotating ro an move in distribution are larger and welding tool is tilte he tool botto ons from the

ure 2. a) Top n of the FSC exerted on egimes of cl ation, as oft der, as it ha sage of fille tral pin to p ns. This will ntal setup iments were FSW tool. T the tool to h eposit a thin ol rotation s n the substr n the substr by the tool p he consuma t is deposite d the substr he depositio been explo dding n surface cla clad layer o hich are dep

friction sur equal or di od (mechtro an intricate n of the fill than the d g of the mat ed sufficien om surface e friction be view of fric C tool allow the substra ladding app ften observe as a relative er material i perform FSW l be the subj e carried ou The should host the fill n clad laye speed, subst rate and the rate by the prior to ejec able filler r ed onto the s ate would b on of relativ ored and the

adding proc n a substrat posited by face claddi fferent mat de). Second e manner wi ler material diameter of erial is prod ntly with re

and the sub etween both tion surface ws for indep ate by the pear, as will ed with frict ely large di is accomplis W experime ject of futur ut on a mod er of the F ler rods, as er on top o trate transla e force app e FSC tool ction of the rods can be surface of th be protected vely soft AA e influence o cess is close te [8]. The c rotation u ing enables terials, whe dly, the fille ith respect t l, see Fig. 2 f the filler duced by fri spect to the bstrate surfa h the tool sh cladding wit endent cont tool should l be shown tion surfacin iameter com shed. Finall ents with th re studies. dified plane FSC tool co visible in F of an AA20 ation speed, plied to pus is measure filler rods i e pushed ou he substrate d against cor A1050 fille of some pro ely related t clad layers c under pressu s the contro ereas frictio er rods do n to the move 2a. In this w rods and iction of the e substrate ace. The tot houlder and th its claddin trol of the fo der. Depend in the next ng [9,10] is mpared to th

ly, the hollo he possibility er machine ontains two Fig. 3. Here 024-T351 su , tool tilt an sh out the f ed by load is set by adj utwards and e. In this wa rrosion over r material o ocess param o the frictio consist of p ure. Howev olled depos n surfacing not need to ement of the way the late

mechtrode. e filler mate (see Fig. 2 tal heat gen the filler ro ng pattern an force exerted ding on the sections. Fu s prevented he filler rod ow FSC too y to add fill that was eq circular op e, two AA1 ubstrate. Th ngle, the for filler rods. cells. The justing the t

d as such p ay the clad

r its full sur onto an AA meters has be on surfacing plasticized la ver, there sition of on g consists o rotate abou e substrate i eral dimens Finally, th erial with th 2b) also by nerated thus ods with the

nd b) its side d on the fill e level of b urthermore, by the pres ds. In this w ol can also b ler material quipped wit penings in 050 filler r he process rce exerted The total d force exer tool height. provide the layer might rface. A2024-T351 een studied. g process as ayers of the are several ne or more of only one ut their own intensifying sions of the he heat for he substrate, the contact consists of substrate. view.

ler rods and both forces , large scale sence of the way a more be equipped l for special th a 13 kW the middle rods will be parameters by the tool down force rted on the During the e t s e l e e n g e r , t f d s e e e d l W e e s l e e e

translation measured; Two filler located wi hardened s a 300 × 18 plate with Experimen The exper surface of the substra rotating, ar substrate m behind the and the to substrate tr experiment applied on Microstru After the e allow for microstruc Subsequen retreating respectivel grinded us with a fina 0.04μm. T 5ml HNO3 The microscopy device emp consecutiv Fin Scanning E phase of th the force ex Figur rods with ith an offse steel and ha 80 mm2 rect steel clamp ntal proced iments star the substrat ate and the re pushed ou moves alon tool until a ol is pulled ravel speed ts. The valu the filler ro uctural ana experiments post-weld ctural obser ntly the sam side (RS) ly. In this ca ing through al polishing he surfaces 3 (70% conc e grain size y. Hardness ploying a 0 ve indents is nally, the el Electron Mi he tool, the xerted on th re 3. A fricti a diameter et of 7.5 mm as a diamete tangular pla ps located at dure rt by lower te. After a s FSC tool, ut towards t g the tool all filler rod d up which and tool til ues of the f ods have be lysis s, the plates aging pro rvation of mples were e are always ase the top h grit silicon g step using s of the spec centrated), 3 e distributio s measurem .98N load a s used to pre lemental co icroscope em tool height he filler rods on surface cl of 5 mm a m from its er of 30 mm ate of 4 mm t 65 mm at e

ing the rot sufficiently the filler su the substrat with a pre-material ha h terminates lt angle are forces exert en varied am s were store ocesses to cross-sectio embedded in on the rig surface of t n papers up g a colloida cimens wer 3ml HCl (37 on of the di ments were p and a 15s lo event mutua omposition mploying E t remains co s is determi ladding shou are put in th centre. Th m with a con m thickness. either side f tating tool y long dwell upply syste te. This form

-defined sp as been used s the experi 600 RPM, ted by the mong the ex ed at room t occur bef ons of the n an epoxy ght and left the substrat p to grade 4 al silica sus re etched by 7%) and 2m ifferent reg performed oading time al interactio of selected Energy-Disp onstant. The ined instead ulder with de he cylindric he FSC sho nical edge. T The substr from the cen

until the sh l phase whe em is switc ms the start eed. During d. Finally, t iment. In th 30 mm min tool should xperiments. temperature fore they w weld wer y resin such ft side of th e remains a 4000. Polish spension wi y Keller's re ml HF (40%) gions of the with an aut e. A minima on. d regions of persive X-ra e feed rate o d. position ope cal opening ulder is ma The filler m rate is clamp ntre line of t houlder of ere the occu hed on and of the depo g this phas the filler sup his work th n-1 and +2.0 der on the s e for a mini were mach e taken ou that the adv he cross se above. The d hing was pe ith a grain eagent, con ). e weld were tomatic mic al distance o f the weld ay spectrosc of the filler enings. gs of the cla anufactured material is d ped on a st the weld. FSC tool t urring frictio d the filler osition phas se a coating pply system he tool rota 0°, respectiv substrate an imum of tw hined. Spec ut using a dvancing sid ection to be discs are m erformed in size of app nsisting of 1 e examined crohardness of 200μm b were deter copy (SEM-r (SEM-rods is not adding tool d from H13 eposited on eel backing touches the on heats up rods, while e. Next, the g is formed m is stopped ation speed, vely, for all nd the force wo weeks to cimens for band saw. de (AS) and e analyzed, mechanically three steps proximately 190ml H2O, d by optical s measuring between the rmined in a EDX). t l 3 n g e p e e d d , l e o r . d , y s y , l g e a

Results an Cladding exerted on tilted with The force i kN, indicat the filler r deposited o The Clearly, a substrate. I Some deta orientation indicate th rotating ac The Fig. 4, is d with the microstruc can be use AA2024 c between th almost pur The results clad layer material. T centre. The treated sur during the precipitate F nd discussio The first s n the substra respect to t is significan ting that rel rods in this on the surfa e macrostru thin layer w It has a wid ails of the n of crystal hat the mate

tion of the F e elemental determined Cu signals ctures of the ed to ident contains Cu he Cu signa re AA1050 s of the hard has a stron The hardne e decrease o rface can m e cladding p s [11]. Figure 4. M Figu on eries of exp ate of 4.0 kN the substrate ntly smaller latively larg case. Nev ace of the su ucture of a tr with a differ dth of appro microstruct s in a direc erial is stro FSC tool co l compositio with SEM-s in Fig. 6 e clad layer

tify the ori u between 3 al in the cla clad layer h dness measu ngly lower ss distribut of the hardn mostly be e process tha Macrostructure ure 5. Micro to the subs periments w N. The tool e surface an r than the su ge frictional ertheless, th ubstrate mat ransverse cr rent micros oximately 2 ture of the ction parall ongly mech oncomitantly on of part o EDX. The m 6b, that w

and the sub gin of the 3.8 – 4.9 % ad layer and has been de urements, a hardness o tion in the ness of the explained fr at affects th e of the trans structure of t strate materia was carried l only partly nd an openi um of the fo l forces exis he filler ro terial. ross section structure is p 21 mm and e clad layer lel to the s hanically de y pressing o of the clad microstruct were determ bstrate mate clad layer, %. The ED d the substr eposited on as shown in over its enti

latter mate substrate w rom the evo he distributi sverse cross the transition al at the a) R d out with a y touches th ing is presen orces exerte st/arise betw ds are push n of the sub present on a thickness r can be se ubstrate su eformed as

out the filler layer, as in ture of this mined at th erial are wel , as AA105 DX measure rate materia top of the Fig. 7, furth ire cross se erial is app with respect olution of t ion and cha

section after n area from t RS, b) centre a relatively he substrate nt on the tra ed on the tw ween the wa hed outward strate mater the top surf s of about 0 een in Fig. rface is evi a result of r rods. ndicated by region is sh he same lo ll visible in 50 virtually ement clearl al. This stro substrate at her support ction than proximately to the mate temperature aracteristics r the cladding he cladding and c) AS. low total d e material as ailing edge wo cladding all of the FS ds and a cl rial is show face of the 0.5 mm in . 5, where vident. The f the compr the black r hown in Fig ocation. Th Fig. 6a. Th y contains ly shows a ongly sugge t this specif t this sugges the AA202 y symmetric erial far awa e with time s of the str g experiment layer down force s the tool is of the tool. rods of 8.5 SC tool and lad layer is wn in Fig. 4. AA2024T3 the middle. the strong fine grains ressive and rectangle in g. 6a, along he different he Cu signal no Cu and a difference ests that an fic location. stion, as the 24 substrate c about the ay from the e and place rengthening t. e s . 5 d s . 3 . g s d n g t l d e n . e e e e e g

Mixing Th exerted on substrate e substrate. I The comparison larger. Alth 4, its depth exerted on influences within the this region signal show that mixing hardness m zone in the be explaine An the substra hardness b influence o growth and AA2024-T welding un changes oc decrease of Figure 6. E Figure 7. he second s n the substra exists on th It also incre e macrostru n to Fig. 4, hough the w h is much la n the substr on the resu refined gra n is shown in ws a lower g of the AA measuremen e top layer o ed by the pr interesting ate material before the cl on the size d re-precipi T351 alloy. nder simila ccur which c f the hardne EDX measure in Fig. 4s Hardness di series of exp ate of 15.0 he trailing s eases the app ucture of a c the extent o width of the arger with v rate materia ulting macr ain region a n Fig. 9a an distinction b A1050 filler nts shown in of the subst resence of s aspect is th l below the ladding trea e and distrib itation phen These relat ar condition can explain ess further a ement near th howing a) th stribution of periments w kN. In this side of the plied force cross section of the modif e modified z values betw al in combi ro and micr as indicated nd the distri between Cu rods with t n Fig. 10 al trate materi substantial a he relatively e modified atment. The bution of th nomena can tively high ns were con n the restora away from t he cladding l he microstruc f the cladded was carried case, no sp tool, forcin on both fill n of the clad fications to zone is com ween 1.7 and ination wit rostructure. by the blac ibution of th u in the sub the AA2024 lso support ial is substa amounts of y high hard zone. The e temperatur he strength occur durin hardness va nfirmed by ation of the o the centre re layer indicate cture and b) sample in V out with a pace betwee ng the fille er rods up t dded substr the structur mparable to t d 2.3 mm. C th the addit EDX mea ck rectangle he Cu signa strate and th 4 substrate m this idea, s antially high relatively h dness values hardness v re evolution ening preci ng the heati alues occur Khodir [1 original har egion (heat ed by the bla Cu content. Vickers scaled relatively l en the FSC er material o 9.6 kN in ate material re at the sub the width o Clearly, the tion of fille surements w e in Fig. 8. al is depicte he modified material has ince the har her than in F ard substrat s measured values are s n in the cent ipitates. Ac ing and coo ring in AA 2-13]. Here rdness in the affected zo ack rectangle d to Fig. 4. large total C tool shoul to be mixe n total. l is shown i bstrate surfa of the clad la large total er material were perfor The micro ed in Fig 9b d zone, whi s indeed occ rdness in th Fig. 7, whic te material. in the centr similar to t ntre region h ccording to oling stages A2024 after e, similar t e centre reg one). e down force der and the ed with the in Fig. 8. In ace is much ayer in Fig. down force has strong rmed again structure of b. The EDX ch suggests curred. The he modified ch can only re region of the original has a strong Jones [11] of FSW of friction stir temperature gion and the e e e n h . e g n f X s e d y f l g ] f r e e

Hardness experiment material a material. A is shown i sections. F have been Figure 8. M Figure 9. E Figure 10 difference ts differ sig discontinue A more deta in Fig. 11. I For the cladd selected (se Figure Macrostructur EDX measur in Fig. 8 sh 0. Hardness d e The hardn gnificantly es change i ailed view o It shows th ded materia ee Fig. 7), fo e 11. Average for claddi re of the tran rement near t howing a) th distribution o ness distribu as shown i in hardness on the chang he average h al the hardne for the mixe

e hardness di ng and mixing nsverse cross the mixing la he microstruc of the mixed utions of cr in Fig. 7 a s is visible ge of the ha hardness of ess values b d material b istribution thro g in the centre s section afte ayer indicate cture and b) C sample in V ross section nd 10. Nea as opposed ardness thro f the substra between -3. between -5.

ough the thick e region of the r the mixing d by the blac Cu content. Vickers scaled ns after the ar the top s d to the top ough the thic

ate of centr 8 and 1.8 m 6 and -0.8 m kness of the su e substrate. g experiment. ck rectangle d to Fig. 8. e cladding a surface of t p surface of ckness of th re regions o mm from the mm (see Fig ubstrate . and mixing the cladded f the mixed he substrate of the cross e centreline g. 10). g d d e s e

The hardness values of the cladded material in the centre region remain approximately constant from the bottom of the substrate up to 3.5 mm and, then, decrease strongly down to below 80 HV in between 3.5 and 4.0 mm indicating the relatively low hardness and strength of the deposited clad layer. For the mixed material case, the hardness remains closer to the hardness of the fresh base material and no rapid decrease is observed near the top surface. However, there is tendency towards greater variation in the hardness values near the top surface that complies with the banded nature of the microstructure as observed in Fig. 9a and b. The variation indicates that the addition of AA1050 in the mixed layer lowers the hardness at this specific location. The addition of AA1050 can be seen in Fig. 9b showing darker bands which contains less copper. Apparently, the friction surface cladding experiment with the current experimental settings causes considerable mixing of the substrate and the filler material, but up to a certain degree.

Conclusions

In this paper the first results of the Friction Surface Cladding (FSC) process, that is related to friction stir welding, have been presented. Based on the observed microstructure, micro hardness and SEM-EDX measurements it has been demonstrated that FSC is capable of deposition of a thin AA1050 clad layer on an AA2024-T351 substrate. By changing the experimental conditions the filler material can also be mixed with the surface region of the substrate material. As such, the FSC process expands the possibilities to clad and/or mix materials on a substrate in the solid state.

Acknowledgements

This research was carried out under project number MC8.07290 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl).

References

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