Uticaj parametara frikcionog zavarivanja mešanjem na otpornost na lom zavarenog spoja legure Al 5083

Friction stir welded is relatively new- solid-states joining process for welded several material such as aluminum, copper, titanium and magnesium. Also FSW technique is preformed in solid state without melting hence avoiding hot cracking. In this research selected aluminum 5083 alloy, it is widely used in applications in which the combination of strength and low weight is attractive. In friction stir welding (FSW) pin connected to a shoulder in rotated and slowly plunged into the joint line between two pieces of plats. When the shoulder tools rotation and contact the material surface, it generated friction heating between the welding tool and the material of the work pieces. This heat causes the latter soften without reaching the melting point and allows traversing of tool along the welding. Friction stir welding presents several benefit for joining of various alloys, specially of aluminum alloy one of the significant advantage of FSW is the heat inputs are small relative to fusion welding techniques and due to the low temperature of the process, material such as Al, Cu, Mg alloys that cannot be welded by fusion processes are easily weld by FSW. On the other hand, FSW has some drawback is often slower traverse rate then some fusion welding and exit hole left when tool is withdrawn. Friction stir welding process generates three distinct microstructural zones that result from the welding process as following: nugget zone also known as the dynamically recrystallized zone (DRZ) where the tool piece pin passes into this zone and by experience, it has high deformation and high heat, generally consists of fine equated grains due to recrystallisation, the thermo mechanically affected zone (TMAZ) and the heat affected zone (HAZ), all zones together are called welding zone. After welded aluminum alloy tested specimens alloy by charpy impact test to evaluate absorbed energy caused the fracture material and toughness of material. Also obtained high resolution images by macro-photographs and by scanning electron microscope (SEM) to evaluate type of surface fracture and detected fracture and micro void in material then analysis material by energy dispersive x-ray spectroscopy (EDX) to shown distribution elements of chemical compound in aluminum alloy after heating and cooling precipitation. Finally, selection the optimized FSW parameters for welded aluminum 5083 alloy, it achieved higher fracture resistance in welded zone of alloy.Frikciono zavarivanje mešanjem predstavlja relativno nov, savremen postupak zavarivanja velikog broja materijala, kao što su legure aluminijuma, bakra, titanijuma, magnezijuma itd. Jedinstvena osobina ovog postupka je da se odvija u čvrstom stanju, bez pojave topljenja. U ovoj disertaciji, ispitivana je Al-Mg legura 5083, koju odlikuje dobra kombinacija čvrstoće, žilavosti i otpornosti na koroziju. Tokom frikcionog zavarivanja mešanjem, specijalno dizajniran alat, koji se rotira, prodire u materijal, upravo u liniji spajanja dve ploče koje se zavaruju. Na kontaktnoj površini oslobađa se toplota koja omekšava materijal, olakšava kretanje alata uz istovremeno mešanje materijala. Ovako zavreni spojevi imaju čitav niz prednosti u odnosu na klasično zavarene spojeve – ukupna potrošnja energije daleko je manja, nema pojave tečnih faza, čvrstoća spoja često bude veća nego kod osnovnog materijala i, konačno, nema štetnih uticaja na prirodnu okolinu. Postoje, naravno, i nedostaci ove tehnologije, pre svega povezani sa dužinom zavarenih spojeva koja zavisi od dimenzija mašine na kojoj se postupak izvodi. Tokom ovog postupka zavarivanja, u zoni zavarenih spojeva javljaju se jasno definisane zone uticaja toplote, kao i kod postupka klasičnog zavarivanja. Međutim, kod frikcionog zavarivanja mešanjem, pojavljuje se i zona termo-mehaničkog uticaja pod simultanog dejstva toplote i plastične deformacije materijala. U ovoj disertaciji, ispitivan je uticaj procesnih parametara frikcionog zavarivanja na čvrstoću zavarenih spojeva. Ispitivan je uticaj (i) rotacione brzine zavarivanja (u opsegu 500 do 800 obrtaja u minuti), (ii) uticaj translacione brzine (75-150 mm/min) i, (iii) uticaj napadnog ugla alata (1°-4°). Svi zavareni spojevi ispitivani su na otpornost prema udarnoj žilavosti. Numeričkom obradom eksperimentalnih rezultata, određena je udarna žilavost zavarenih spojeva kao i brzina i energija loma. Pored mehaničkih ispitivanja, izvršena su opsežna mikrostrukturna ispitivanja primenom optičkog i skening elektronskog mikroskopa (SEM). Ova ispitivanja omogućila su bolji uvid u mehanizam i kinetiku duktilnog loma zavarenih spojeva. Konačno, na osnovu analize mehaničkih i mirostrukturnih ispitivanja, određeni su optimalni parametri frikcionog zavarivanja ispitivane legure.Navedeni su: mentor (contributor advisor), članovi komisije (contributor other

Impact fracture response of friction stir welded Al-Mg alloy

Ispitivani su uticaji parametara frikcionog zavarivanja mešanjem na ponašanje loma udarom po Šarpiju u leguri Al-Mg 5083. Rotaciona i poprečna brzina zavarivanja su povezane sa dinamičkom inicijacijom prsline i duktilno čupanje. Mehanizam loma je razjašnjen numeričkom i fraktografskom analizom. Rezultati pokazuju da na inicijaciju i na stabilan rast prsline ne utiču toliko parametri postupka zavarivanja, koliko deformaciono ojačavanje ispitane legure. Međutim, konačna nestabilna faza duktilnom cepanja u velikoj meri zavisi od grešaka unutar zone mešanja u metalu šava.Effects of friction stir welding (FSW) variables on the Charpy impact fracture behaviour of Al-Mg 5083 alloy are investigated. Rotational and traversal welding rates are linked to the dynamic crack initiation and ductile tearing. The fracture mechanism is clarified by numerical and fractographic analysis. Results had revealed that initiation and stable crack propagation is not significantly influenced by the applied welding variables. It is attributed to the strain hardening of the investigated alloy. However, the final unstable phase of ductile tearing is strongly susceptible to the imperfections in the stirring zone of the weld

Crack resistance of aluminium alloy friction stir welded joint

Charpy testing is conducted on a high-speed data acquisition instrument, using instrumented pendulum to separate energies for crack initiation and propagation. The J-R curves are used to determine JIc, as the measure of fracture toughness. The Taguchi method with a special design of orthogonal matrices to reduce the number of experiments to a reasonable level has been applied

Crack resistance of aluminium alloy friction stir welded joint

Charpy testing is conducted on a high-speed data acquisition instrument, using instrumented pendulum to separate energies for crack initiation and propagation. The J-R curves are used to determine JIc, as the measure of fracture toughness. The Taguchi method with a special design of orthogonal matrices to reduce the number of experiments to a reasonable level has been applied

Influence of friction stir welding parameters on properties of 2024 t3 aluminium alloy joints

The aim of this work is to analyse the process of friction stir welding (FSW) of 3 mm thick aluminium plates made of high strength aluminium alloy - 2024 T3, as well as to assess the mechanical properties of the produced joints. Friction Stir Welding is a modern procedure which enables joining of similar and dissimilar materials in the solid state, by the combined action of heat and mechanical work. This paper presents an analysis of the experimental results obtained by testing the butt welded joints. Tensile strength of the produced joints is assessed, as well as the distribution of hardness, micro-and macrostructure through the joints (in the base material, nugget, heat affected zone and thermo-mechanically affected zone). Different combinations of the tool rotation speed and the welding speed are used, and the dependence of the properties of the joints on these parameters of welding technology is determined

Charpy and SEM investigation of Al-Mg friction stir weldments

Influence of friction stir welding processing variables on Charpy impact fracture behaviour of Al-Mg 5083 alloy was studied. Rotational and traversal welding rates were linked to the dynamic crack initiation and ductile tearing. Fracture mechanism was examined by numerical and fractographic analysis. Results revealed that initiation and stable crack propagation were significantly influenced by applied heat input variables. It was attributed to the strain hardening of the investigated alloy. The final, unstable phase of the ductile tearing is strongly susceptible to the imperfections in the stirring zone of the welded joint

Charpy and SEM investigation of Al-Mg friction stir weldments

Influence of friction stir welding processing variables on Charpy impact fracture behaviour of Al-Mg 5083 alloy was studied. Rotational and traversal welding rates were linked to the dynamic crack initiation and ductile tearing. Fracture mechanism was examined by numerical and fractographic analysis. Results revealed that initiation and stable crack propagation were significantly influenced by applied heat input variables. It was attributed to the strain hardening of the investigated alloy. The final, unstable phase of the ductile tearing is strongly susceptible to the imperfections in the stirring zone of the welded joint

Impact Toughness of Friction Stir Welded Al-Mg Alloy

Al-Mg 5083 alloy was friction stir welded by varying welding variables, i.e., rotational speed, traversal speed and tool tilt angle. Welded specimens have been tested by the instrumented Charpy test to evaluate total absorbed energy, as well as the energy for crack initiation and the energy for crack growth. Subsequently, the fracture surface was examined by optical and scanning electron microscopy (SEM) to evaluate surface type of fracture, and to correlate the microstructure with the impact energy. Based on this, the optimum windows of FSW parameters for Al-Mg 5083 alloy welding have been defined

Impact Toughness of Friction Stir Welded Al-Mg Alloy

Al-Mg 5083 alloy was friction stir welded by varying welding variables, i.e., rotational speed, traversal speed and tool tilt angle. Welded specimens have been tested by the instrumented Charpy test to evaluate total absorbed energy, as well as the energy for crack initiation and the energy for crack growth. Subsequently, the fracture surface was examined by optical and scanning electron microscopy (SEM) to evaluate surface type of fracture, and to correlate the microstructure with the impact energy. Based on this, the optimum windows of FSW parameters for Al-Mg 5083 alloy welding have been defined

Superplastic deformation of an x7093 al alloy

We have investigated the superplastic deformation mechanism of a powder-metallurgy, high-zinc X7093 Al alloy. The objective was to examine the rate-controlling mechanisms that govern its superplastic deformation. The investigations were carried out in the temperature range 490-524 degrees C and strain rates of 4.17 x 10(-5) s(-1) to 2.1 x 10(-2) s(-1). The maximum ductility was slightly more than 500% at 524 degrees C and 4.2 x 10 s(-1). The values of the stress exponent (n) and the activation energy (Q) indicated that the deformation is rate-controlled by the climb within the grain-boundary diffusion path. The existence of a temperature-dependent threshold stress was confirmed