FRICTION STIR WELDING OF NON-WELDED ALUMINIUM ALLOYS ZGRZEWANIE TARCIOWE NIESPAWALNYCH STOPÓW ALUMI-NIOWYCH METODĄ FSW

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1 D.Sc. Romn BOGUCKI* D.Sc. Adm PIETRAS** Prof. Ph.D. D.Sc. Adm WIŚNIEWSKI*** * Reserch nd Development Centre for Mechnicl Applinces Ltd Co ** Institute of Welding *** Militry Institute of Armment Technology FRICTION STIR WELDING OF NON-WELDED ALUMINIUM ALLOYS Astrct: The principle of Friction Stir Welding (FSW) nd the wy the plsticized mterils move during the welding process re presented in this pper. The optiml welding conditions were determined. Findings of friction stir welding of screw mde of luminium lloy EN AW-2017A to the flt ottom of the cssette mde of cst luminium lloy EN AC re presented. From the microscopy exmintion, conducted for the specimens which were tken from the different res of weld, rises tht on the entire length of the welding re metllic connection occurs. Results of the hrdness test conducted in the weld zone in ccordnce with PN EN nd results of the drop test from the height of 12 meters re presented. The rnge of tests of the joints of cssettes with the screws, welded with FSW, indispensle to mke efore the implementtion into production re determined. ZGRZEWANIE TARCIOWE NIESPAWALNYCH STOPÓW ALUMI-NIOWYCH METODĄ FSW Streszczenie: W prcy przedstwiono zsdę zgrzewni trciowego z mieszniem mteriłu zgrzeiny metodą FSW (Friction Stir Welding) orz sposó przemieszczni się uplstycznionych ms mteriłu podczs procesu zgrzewni. Określono optymlne wrunki zgrzewni orz przedstwiono wyniki dń zgrzewni FSW prętów wycisknych ze stopu EN AW-2017A z płski dnem ksety ERAWA, wykonnych z odlewniczego stopu luminium EN AC Wyniki dń mikroskopowych próek pornych z różnych oszrów zgrzewni wskzują n występownie ciągłego powiązni metlicznego n cłej długości złącz. Przedstwiono wyniki dń twrdości prowdzonych w zgrzeinie FSW zgodnie z normą PN EN orz wyniki dń po próie zrzutu kset z wysokości 12 m. Określono zkres niezędnych dń eksplotcyjnych i dń ostrzłem lekkich kset ze stopu luminium ze śrumi ze stopu luminium zgrzewnych z pomocą metody FSW przed wdrożeniem ich do produkcji. 1. Introduction Friction Stir Welding (FSW) technology ws invented nd ptented y TWI Ltd in 1991 [1]. The principle of the FSW process nd the scheme of displcement of welded mterils is shown in Figure 1. 7

the tool with rottionl pin is plced in the contct line of the sheets, hets nd plsticizes the mteril in this re.

Heted nd plsticized mteril is moved ckwrds ehind the tool, is mixed nd efore solidifiction is eing thickened y the shoulder. The sem weld is creted ehind the tool.

2 Fig. 1. The principle of the FSW process [2]: V n - rottionl speed of the tool, V zg - welding speed, JZ the nugget, MR - se mteril, SWC - het ffected zone, SUM - thermo- mechnicl ffected zone In this method the tool with rottionl pin is plced in the contct line of the sheets, hets nd plsticizes the mteril in this re. After put of the tool into the rottionl speed, its penetrtion in the contct line of welded sheets, het nd plsticize of the mteril in ner re of the tool, mixing of the welded mterils tkes plce. Heted nd plsticized mteril is moved ckwrds ehind the tool, is mixed nd efore solidifiction is eing thickened y the shoulder. The sem weld is creted ehind the tool. The properties of the weld depend on the welding prmeters [2, 3]. Investigtions of the test welds confirm tht it is possile to chieve good qulity of friction stir welded joints [2, 4]. 2. Investigtion of the friction stir welding conditions Anlyses nd investigtions of the welding conditions of the joint of two screwed screws with the plte were conducted [5, 6]. Tking into considertion tht there re no stndrds concerning the tests of the FSW joints, the qulity ssessment of test joints were conducted in ccordnce with the Polish stndrd like for the resistnce welds [7]. Lortory tests of the welding conditions were conducted on the flt smples mde of the csting luminium lloy EN AC nd extruded screws mde of the luminium lloy EN AW-2017A [6]. The mechnicl properties of the mterils re presented in Tle 1. Tle 1. Mechnicl properties of tested luminium lloys [8, 9] Seril numer Mteril type Mteril form Stte Dimension, mm 1. EN AC (ALSi7Mg0,3) 2. EN AW-2017A (Cu4MgSi(A)) R M, MP min. R 02, MP min. A,% min. Cst (smples T csted seprtely) Extruded screws T4 φ Investigtions included selection of the shpe nd dimensions of the tool nd determintion of the preliminry welding conditions of luminium lloys, considered to e unweldle with other welding methods. As result of investigtions nd exmintions the following FSW welding prmeters of screws with the ottom of ERAWA rective cssette were determined: 1. friction rottion speed min -1 ; 8

2. 3. welding speed - 224 mm/min; inclintion ngle of tool - 0 ; The view of the joints from the fce nd the root side of the weld is shown in

4 [10] Frgments of the ERAWA cssette fter the peel test (the view from the side of the tool nd from the side of the screwed screw) re shown

Peel of the screws through their pulling out from the ottom of the cssette, round the het ffected zone took plce, similrly to the typicl

The view of the cssette fter the peel test of the screws: from the side of the tool, from the side of the screw [6] It ws found tht the igger

3 2. 3. welding speed mm/min; inclintion ngle of tool - 0 ; The view of the joints from the fce nd the root side of the weld is shown in Figure 2. Fig. 2. The view of the joints fter FSW process: form the fce side of the weld, from the root side of the weld, smple no. 4 [10] Frgments of the ERAWA cssette fter the peel test (the view from the side of the tool nd from the side of the screwed screw) re shown in Figure 3. Exmintions of FSW joints showed the proper qulity of joints. Peel of the screws through their pulling out from the ottom of the cssette, round the het ffected zone took plce, similrly to the typicl joints mde with conventionl welding methods. Fig. 3. The view of the cssette fter the peel test of the screws: from the side of the tool, from the side of the screw [6] It ws found tht the igger tool ws used in the FSW process the lrger ws the weld nd the higher ws the tensile strength of the joint. The specimens for microscopic exmintions were cut cross the weld line. Typicl mcrostructures of welds otined during the FSW process in the initil () nd in the finl () welding re re presented in Figure 4. 9

conducted in ccordnce with the Polish Stndrd PN EN 1043-2 [11].

Microstructure exmintions showed very good connection etween the mteril of the screw nd the mteril of the cssette s ottom.

4 Fig. 4. Mcrostructure of FSW weld: - initil welding re, - finl welding re, Keller etching, mgnifiction 8x [6] Hrdness test of joints were conducted in ccordnce with the Polish Stndrd PN EN [11]. The typicl run of the hrdness penetrtion pttern in the cross-section of the joint is shown in Figure 5. Microstructure exmintions showed very good connection etween the mteril of the screw nd the mteril of the cssette s ottom. On the entire length of the welding re, indiscrete metllic connection occurs. No crcks nd discontinuities of microstructure of joint were oserved. Typicl res of joint re shown in Figure 6. Fig. 5. The hrdness penetrtion pttern in FSW weld: 1 - hrdness of the mteril of the cssette s ottom 54 HV30, 13 - hrdness of the screw s mteril 87 HV30 [6] 10

Mgnifiction 1000x Mgnifiction 200x Fig. 6.

Drop tests of the ERAWA-2 cssette The field investigtions of the qulity of

38) WITU - Zielonk. ERAWA-2 cssettes no.

use of explosive, flling down freely from the height of 12 meters hit the

During the tests the cssettes underwent plstic deformtions (Figure 7 10).

5 Mgnifiction 1000x Mgnifiction 200x Fig. 6. Chrcteristic res of weld (nitl etching) 3. Drop tests of the ERAWA-2 cssette The field investigtions of the qulity of cssettes were conducted in ccordnce with the reserch proceeding no. 38 (LBAR.38) WITU - Zielonk. ERAWA-2 cssettes no.: 1, 6 nd 8, filled with the inert mteril of the weight like in cse of the use of explosive, flling down freely from the height of 12 meters hit the concrete from the screw side, the side wlls nd the cover. During the tests the cssettes underwent plstic deformtions (Figure 7 10). In cse of exceed of llowle stresses, crcks occurred in the SWC of the weld or in the res of corners. Crcks nd filures of the rivets, joining the cssettes with the cover, lso occurred. Fig. 7. Cssettes no. 1 fter the first drop on the concrete from the height of 12 meters Fig. 8. Cssettes no. 1, 6 nd 8 fter the first drop on the concrete from the height of 12 me- ters 11

Fig. 9. The ottom () nd the corner () of the cssette no. 6 fter the sixteenth drop from the height of 12 meters on the concrete Fig. 10. Frgment of the prt of the cssette no.

6 cssette which ws dropped down s mny s 16 times till the totl destruction ws chieved.

The numer of drops until the totl destruction of the ERAWA-2 cssette ws chieved determintes the qulity of performnce of the cssette nd the connection of the screws with the use of FSW method. 4.

On the se of crried out tests the following conclusions were drwn: The most fvourle friction stir welding prmeters for welding screws mde of the luminium lloy EN AW 2017A (screws) to the ottom of

6 Fig. 9. The ottom () nd the corner () of the cssette no. 6 fter the sixteenth drop from the height of 12 meters on the concrete Fig. 10. Frgment of the prt of the cssette no. 6 fter the sixteenth drop on the concrete from the height of 12 meters The est results were otined for the ERAWA-2 no. 6 cssette which ws dropped down s mny s 16 times till the totl destruction ws chieved. Brek of the rivets nd seprtion of the ottom from the sides of the cssette took plce, ut the joint of the screw with the ottom of the cssette ws not destroyed. The numer of drops until the totl destruction of the ERAWA-2 cssette ws chieved determintes the qulity of performnce of the cssette nd the connection of the screws with the use of FSW method. 4. Conclusions On the se of crried out tests the following conclusions were drwn: The most fvourle friction stir welding prmeters for welding screws mde of the luminium lloy EN AW 2017A (screws) to the ottom of the cssette mde of the luminium lloy EN AC were determined. Welds mde with the FSW method hve compct nd constnt structure in entire welding re, free from surfce defects nd irregulrities. FSW method is suitle to joining luminum screws to the ottom of the cssette mde of the cst luminum lloys. FSW process conducted in the suitle conditions gurnties crrying out joints of the proper nd repetle qulity. The use of the FSW method to join the screw to the ottom of the ERAWA-1 cssette nd ERAWA-2 cssette ensures tht the connections re: Durle in rugged conditions - e.g. driving in the field with high speed, etc.; 12

7 Resistnt even during the 155 mm rtillery shell urst HE in the vicinity of the vehicle nd lso during the explosion of the mine 10 kg in weight under the vehicle, in ccordnce with the stndrd STANAG 4569 for IV nd V protection level: Protection level IV IV V Shot s prmeters Weight Artillery shells Distnce, m 25 Azimuth, δ 360 o Elevtion, γ 0 90 o Ammunition 155 mm HE Velocity, V o 960 ±20 m/s 10 kg mine s explosion under: Any wheel or cterpillr Center of the vehicle ody corrosion resistnt etween different mterils, like in cse of the use of screw mde of steel with the cssette mde of luminium lloy; tight: during cssettes filling; in rugged conditions - moisture, rin, snow, overcoming of wter-ostcle. 6. The use of FSW method to join screws to the ottom of the ERAWA-1 nd ERAWA-2 cssettes llows reduce their weight in reltion to the cssettes with the steel screws. 7. The prcticl use of the cssette mde of the luminium lloy ERAWA-1 i ERAWA-2 welded with the screws of the luminium lloy with the use of FSW method cn tke plce fter reliztion of the following tests: ) Accelerted geing test, ) Fire with the ullets: 12,7 mm type B-32, 14,5 mm type B-32, c) sttic evlution of protection ility during the punching with hollow chrge projectile PG-7; d) sttic - evlution of mount of deformtion of djcent cssettes during initition of the middle cssette in the set of nine ERAWA-1 nd ERAWA-2 cssettes; e) sttic - evlution of mount of deformtion of cssettes during explosion of the mortr om in the vicinity of them; f) sttic evlution of rection of cssette in the consequence of urning of petrol; g) sttic - evlution of rection of cssette in the consequence of urning of nplm on it; h) sttic - evlution of rection of cssette in the consequence of urning of the wrhed with termit on it; i) operting during the drive of the tnk with cssettes on the surfce nd unsurfce rod in ccordnce with the determined proceeding. References [1]. Thoms W.M.: Friction stir utt welding. GB ptent , , Interntionl ptent ppliction PCT/GB92/ [2]. Bogucki R.: Elortion of friction stir welding conditions of high-strength sheets mde of luminium lloys (series 6000) with new SFW method for sfety systems. Project of MNiSW no R , no 5/TP/2008, OBRUM Sp. z o.o., not pulished,

8 [3]. EuroStir Σ!2430 Europen Industrilistion of Friction Stir Welding [4]. Collign K.J., Gover J., Vze S.P., Xu J., Ritter R., Picknes J.R.: Friction Stir Welding of Thick Section Aluminium Alloys. Concurrent Technologies Corportion, 100 CTC Drive, Johnstown, PA , USA. [5]. Bogucki R.: Construction joint. Inventive project no 14/08/05/OBR, [6]. Pietrs A., Mir D., Kowieski Sz.: The elortion of the technology of the Welding conditions with FSW metod of two olt to the flt ottom. Development work, no B- 150/2/09. Instytut Spwlnictw, not pulished, Pietrs A., Mir D., Kowieski Sz.: Oprcownie technologii zgrzewni trciowego metodą FSW korpusu z dwiem śrumi, prc dwcz nr B-150/2/09. Instytut Spwlnictw, niepulikowne, 2009 [7]. PN-M-69006:1997, Welding. Technologicl testing of spot nd projection welded joints in metl sheet. [8]. PN-EN 1706:2001, Aluminium nd luminium lloys. Csts. Chemicl composition nd mechnicl properties. [9]. PN-EN :2001, Aluminium nd luminium lloys. Extruded rod/r, tue nd profiles. Mechnicl properties. [10]. Bogucki R.: Model of the cssette welded with FSW method. Development work, no 2/TP/09, OBRUM sp. z o.o., not pulished, [11]. PN-EN :2000, Welding. Non-destructive exmintion of welds. Hrdness test. Micro-hrdness test of welds. 14

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