Effect of cathodic polarization on failure and degradation of mechanical properties of some aluminum alloys

Journal of KONES. Powertrain and Transport

2014

The results of corrosion properties research of aluminum alloy AW 7020 (AlZn5Mg1) welded by Friction Stir Welding were presented. In the article the parameters for friction stir welding of sheets made of AlZn5Mg1 (7020) alloy were presented. Corrosion tests were performed on the surface of the FSW joined sheets depending on the distance from the centre of the weld. EIS measurement was performed in three-electrode system in an artificial seawater (3.5% NaCl). Impedance studies were carried out at the corrosion potential. Changed voltage signal amplitude in the range ± 10 mV and frequency range of changes was as follows: 100 kHz-0.1 Hz. Atlas 0531 EU & IA potentiostat was used for studies. Model in the form of an electrical equivalent circuit replacement was chosen for the test object. The results of electrochemical impedance spectroscopy are presented graphically in the Nyquist charts matched with the theoretical curve to them and in the form of parameters characterizing the corrosion process. Obtained results were statistically analysed. Better resistance to electrochemical corrosion was found for the native material then joint welded by FSW of 7020 aluminum alloy. Worse corrosion properties were observed in the advancing side of the weld than in the retreating side of the weld. Original value are received results of the corrosion properties distribution of FSW welded AW-7020 aluminium alloy.

Section: Introductionmentioning

confidence: 99%

Corrosive Properties Distribution in Aw-7020 Alloy Joints Welded by FSW

Journal of KONES. Powertrain and Transport

2014

“…The disadvantage of the 7xxx series alloys is that they are prone to stress and layer corrosion. Many years of research have shown that the resistance of these alloys to stress corrosion is influenced among other things by heat processing, chemical composition and welding technology (welding method, type of fillers, type of joint) [1][2][3][4]. Virtually all joints welded using conventional MIG or TIG methods in this group of alloys possess insufficient resistance to stress or layer corrosion.…”

Section: Introductionmentioning

confidence: 99%

“…This significantly reduces the size of the heat-affected zone. Studies of Al-Zn-Mg alloys bonded using MIG and TIG methods exposed to aggressive marine environment have shown a low resistance to stress and layer corrosion occurring just in the heat-affected zone [4,5,7]. Studies on the electrochemical corrosion resistance of AW-7020 alloy and its joints welded by FSW supplement knowledge about the environmental destruction of that material.…”

Section: Introductionmentioning

confidence: 99%

EIS Research of AW-7020 Alloy Joints Welded by FSW

Charchalis

2013

SSP

The results of corrosion properties research of aluminum alloy AW 7020 (AlZn5Mg1) welded by friction stir welding FSW were presented. Friction Stir Welding (FSW) a new technology can be successfully used for butt welding of different types of aluminum alloy sheets. In the article the parameters for friction stir welding of sheets made of AlZn5Mg1 (7020) alloy was presented. The study was carried out in accordance with the requirements of the ASTM G 106. EIS measurement was performed in three electrode system in an artificial seawater (3.5% NaCl). Impedance studies were carried out at the corrosion potential. Changed voltage signal amplitude in the range ± 10 mV and frequency range of changes was as follows: 100 kHz - 0.1 Hz. Atlas 0531 EU & IA potentiostat was used for studies. The results of electrochemical impedance spectroscopy are presented in the form of parameters characterizing the corrosion process. Obtained results were statistically analyzed. The electrochemical impedance spectroscopy studies have shown that the joint welded by FSW has better electrochemical corrosion resistance than the native material - AW-7020 alloy. Original value are received results of the corrosion properties of new method friction stir welded AlZn5Mg1 alloy compared with the native material.

“…The disadvantage of the Al-Zn-Mg alloys is that they are prone to stress and layer corrosion. Many years of research have shown that the resistance of these alloys to stress corrosion is influenced among other things by heat processing, chemical composition and welding technology (welding method, type of fillers, type of connector) [1][2][3][4]. Virtually all joints welded using conventional MIG or TIG methods in this group of alloys possess insufficient resistance to stress or layer corrosion and therefore the only materials for hulls of light vessels are still Al-Mg 5xxx group alloys.…”

Section: Introductionmentioning

confidence: 99%

Influence of Friction Stir Welding on Hardness Distribution in Joints of AlZn5Mg1 Alloy

Charchalis

2013

SSP

The article presents the research results of hardness values distribution of friction stir welded joint (FSW) alloy AW 7020 (AlZn5Mg1). FSW is a method of welding in the solid state, mechanical properties of joints welded by that method can be higher than that for arc welding techniques (MIG, TIG). The parameters of friction stir welding (FSW) used to join 7020 alloy were presented. Metallographic analysis showed the correctly structured FSW welded 7020 alloy. The study was carried out using Vickers hardness HV5 in accordance with the requirements of the Polish Standard PN-EN 6507 using a hardness testing machine HPO-10. The location of measurement points in the butt joint was determined in accordance with PN-EN 1043-1:2000. The indenter load was 49 N. In order to determine the effect of bonding method on structure change of the material microscopic examination was performed using an optical microscope ZEISS Axiovert 25.The test specimens were polished and then etched with KELLER reagent. This enabled the precise identification of zones present in the joint, such as: weld nugget, thermo-mechanically affected zone, native material. To determine the grain size in the different zones of joints bonded by FSW AxioVision 4.8.2 software was used. Hardness testing in across researched joints showed that the highest value of hardness is in the weld and the lowest is in the native material.