Intergranular Corrosion Following Friction Stir Welding of Aluminum Alloy 7075-T651

Lumsden, J. B.; Mahoney, Murray W.; Pollock, G.; Rhodes, C. G.

doi:10.5006/1.3283950

Cited by 110 publications

(80 citation statements)

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“…The high generation heat input sensitizes the grain boundaries in the HAZ region during the welding process over time. Similarly, the thermal transients experienced during FSLW changed both the grain boundary chemistry and the chemistry in the grain near the boundary selectively sensitizing the grain boundary region to varying degrees 15 . By contrast, in the WNZ region in FSLW 1 and FSLW 2, no intergranular attacks were observed; however, in the WNZ (Figure 8), more severe localized pit dissolution took place in FSLW 2 than in FSLW 1.…”

Section: Observation Of Corrosion Morphologymentioning

confidence: 99%

“…Elimination of these defects by using friction-stir welding (FSW), which is a solid-state process, substantially increases an alloy's corrosion resistance 8 . The corrosion of aluminum alloy friction-stir welds is commonly investigated using methods such as immersion tests, polarization techniques, electrochemical impedance *e-mail: khamirul@upm.edu.my spectroscopy (EIS), stress corrosion cracking (SCC) tests, and cyclic spray tests [8][9][10][11][12][13][14][15][16][17][18][19] . Accordingly, the corrosion behavior of the FSW in different aluminum alloys has been examined by a number of authors [10][11][12][13][14][15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

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Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

Gharavi

Матори

Yunus³

et al. 2014

Mat. Res.

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In this work, the corrosion behaviors of friction-stir lap welding of 6061-T6 Al-alloy are studied. The friction-stir lap welding was performed under different welding conditions (rotation speed and welding speed). The corrosion behavior of the parent alloy, the weld nugget zone (WNZ), and the heat affected zone (HAZ) of each welded sample working as an electrode, were investigated by the Tafel polarization test in 3.5 wt. (%) NaCl at ambient temperature. The morphology of the corroded surface of each region was analyzed by scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS). The results showed that the corrosion resistance of the parent alloy was better than the WNZ and the HAZ in both welding conditions. Localized pit dissolution and intergranular corrosion were the dominant corrosion types observed in the parent alloy, WNZ, and HAZ. The parent alloy, WNZ, and HAZ exhibited similar corrosion potentials (E corr ) after T6 heat treatment. This treatment had a better effect on the corrosion resistance of the welded regions than the parent alloy.

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Section: Observation Of Corrosion Morphologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

Gharavi

Матори

Yunus³

et al. 2014

Mat. Res.

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“…Los principales aleantes presentes en la aleación 7075 son el Zn, Mg y Cu, los cuales forman precipitados endurecedores, en particular el MgZn 2 y el MgAlCu, durante el tratamiento térmico de envejecimiento [5,8,9]. La designación T651 de esta aleación indica que el tratamiento térmico aplicado es un tratamiento de solubilización a 465 ºC, templado y luego un envejecido a 120 ºC por 24 h, de manera de alcanzar la dureza máxima.…”

Section: Introductionunclassified

Comportamiento frente a la corrosión de uniones soldadas por fricción agitación de AA7075-T651: Evaluación galvánica

et al. 2018

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RESUMENLa soldadura por Fricción Agitación (FSW) es un proceso en estado sólido que ha revolucionado la soldadura de aleaciones de aluminio. La industria aeronáutica y otras han incorporado este proceso para la fabricación de elementos estructurales, empleando aleaciones de alta resistencia como las conocidas AA7075 o AA2024.Durante la FSW se forman, como consecuencia del ciclo termomecánico aplicado, distintas zonas entre las que se encuentran la zona agitada (WN), la zona termomecánicamente afectada (TMAZ), y la zona térmicamente afectada (HAZ). Cada una de ellas presenta características metalúrgicas diferenciadas, por lo que la resistencia a la corrosión podría verse afectada.El objetivo de este trabajo fue estudiar el comportamiento frente a la corrosión de uniones soldadas por FSW en AA7075-T651. Para ello, se soldaron probetas de (150x150) mm de AA7075-T651 por FSW con una velocidad de rotación de 680 rpm y dos velocidades de avance: 51 mm/min y 206 mm/min. Se realizó una caracterización microestructural de las diferentes zonas de la soldadura, y se analizó el comportamiento galvánico a través de ensayos de inmersión en una solución de 3,5% de NaCl sin eliminación de oxígeno y de ensayos de contacto con gel al 3% de agar, 3,5% de NaCl y solución de indicador de pH universal. Se extrajeron muestras para la caracterización microestructural del ataque.Se observó la presencia de un ataque localizado en la interfase TMAZ-HAZ caliente. La caracterización a través de SEM indicó un ataque intergranular de gran envergadura, con la coalescencia de diversos ataques. Se observó una preponderancia del ataque en el lado de retroceso de soldadura.Palabras clave: Corrosión, FSW, soldadura, galvánico. ABSTRACTFriction Stir Welding (FSW) is a novel solid-phase welding process, which has proved to have a great potential for the realization of welded joints in materials with poor weldability such as heat-treatable aluminum alloys. The aerospace industry has incorporated this process for the manufacture of structural elements, using known high strength alloys such as AA7075 or AA2024.During FSW, different areas are formed due to the thermomechanical cycle applied, which have been named: the stirred zone (WN), the thermo-mechanically affected zone (TMAZ) and the heat affected zone (HAZ). Each zone presents different metallurgical characteristics, so the corrosion resistance could be affected. This is a relevant aspect for multiple applications and the implications are still not clear.

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“…These latter weld zones appear to be the most corrosion susceptible regions [3,4]. Recently, the effect of natural, artificial and RRA aging on the properties and structure of 7-xxx series aluminum alloys [5,6], and on the mechanical and corrosion properties of 7249 and 7075 aluminum alloys [7,8] as well as the effect of temperature and exposure on precipitates morphology, strength and plasticity [9] were investigated.…”

Section: Troductiomentioning

confidence: 99%

Environmental Cracking and Impact Investigations after Short-Term Temperature Treatments: 7050-T7451 Friction Stir Weld

Paglia

2010

MSF

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The influence of short-term heat treatments on the environmental cracking and impact properties of a 7050-T7451 friction stir weld were investigated. Prisms, cut transverse to the welding direction, were exposed for minutes at temperatures between 100 o C and 800 o C in an oven or exposed to a propane torch flame and/or water / air quenched. A significant increase in the environmental cracking resistance (ductility ratio from 0.2 to 0.9) was observed for samples exposed to temperatures below the solutionizing limit, but between 240 o C and 280 o C. The fracture location changed from the "soft" heat affected zones to the nugget. Furthermore, the weld exhibited a decrease in the Charpy impact adsorbed energy as compared to the weld unaffected parent metal. An increase in the temperature improved the adsorbed energy, while a temperature decrease promoted the brittleness and reduced the adsorbed energy. The flow contours, also called onion ring bands, present within the nugget, represented a preferential fracture path during impact. The high temperature treatments followed by water quenching did not significantly improved the resistance to impact. I TRODUCTIOThe temperature developed during the friction stir welding (FSW) of high strength 7-xxx series aluminum alloys promotes a coarsening of precipitates and a widening of the precipitate-free zones, in particular within the heat affected zones of the weld [1,2]. These latter weld zones appear to be the most corrosion susceptible regions [3,4]. Recently, the effect of natural, artificial and RRA aging on the properties and structure of 7-xxx series aluminum alloys [5,6], and on the mechanical and corrosion properties of 7249 and 7075 aluminum alloys [7,8] as well as the effect of temperature and exposure on precipitates morphology, strength and plasticity [9] were investigated. In this concern, conventional post-weld heat treatments have been used to partially restore the properties of the welds. These treatments often reached solutionizing temperatures and the samples were subsequently subjected to re-aging processes [10,11,12]. A non-conventional post-weld heat treatment was also applied to AA 7075-T651 [13], obtaining an increase in the corrosion properties. This was mainly due to the local dissolution of precipitates, in particular along the grain boundaries. Nevertheless, short-term heat treatments that might modify the properties of the welds are currently on an initial investigation stage.Like the corrosion, the resistance to impact is an important property of engineering components subjected to dynamic loading. The temperature also control the fracture behaviour. The fracture proceeds, for ferritic alloys, through microvoid coalescence (ductile behaviour), adsorbing energy, or through cleavage, for brittle behaviours. In this latter case, the energy adsorbed decreases with a reduced toughness of the material [14]. The influence of notch severity and temperature on the impact were also tested for AA 7055. The fracture toughness of 45 o notched samples ...

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Intergranular Corrosion Following Friction Stir Welding of Aluminum Alloy 7075-T651

Cited by 110 publications

References 0 publications

Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

Comportamiento frente a la corrosión de uniones soldadas por fricción agitación de AA7075-T651: Evaluación galvánica

Environmental Cracking and Impact Investigations after Short-Term Temperature Treatments: 7050-T7451 Friction Stir Weld

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