Surface remelting treatment of 7075 aluminum alloy—microstructural and technological aspects

Abstract

7075 aluminum alloy in the T6 state was subjected to surface remelting treatment using Gas Tungsten Arc Welding (GTAW). The changes in the material microstructure were examined by means of light microscopy, scanning electron microscopy and EDS. Moreover, profilometric tests and comparative measurements of material hardness in the state before and after the treatment were conducted. In the remelted layer strong microstructure refinement and the disappearance of microstructure banding were found. A fine dendritic microstructure was dominant in the remelted zone. Use of the GTAW method reduced the number of intermetallic precipitates in the surface layer. A consequence of dissolving the precipitates was a decrease in the hardness of the material in relation to the hardness before the modification. All the samples were characterized by the presence of a remelted zone, a narrow partially remelted zone and a wide heat affected zone. With an increase in the heat source travel speed, and consequently less heat entering the remelted material, the dimensions of the individual zones decreased. The conducted research showed that GTAW technology can be used in the surface remelting treatment of aluminum alloys and can be a competitive solution in comparison to other technologies.

Evolution of Microstructure and Properties of Air-Cooled Friction-Stir-Processed 7075 Aluminum Alloy

“…On the other hand, the Hall–Petch equation does not take into account the numerous microstructural factors that affect or can affect the hardness of a material. In the case of the 7075 aluminum alloy, such a factor is intermetallic phase precipitates, which strengthen the material and improve its mechanical properties [ 62 ]. The potential decrease in hardness of the 7075 aluminum alloy may be a result of the dissolution of the precipitates during FSP.…”

The Investigation of the Effects of T6 and High Temperature Pre-precipitation HTPP Heat Treatments on Hot Tensile Properties of AA7075 Aluminium Alloys

“…Yaşlandırma ısıl işlemlerinin AA7075 alaşımının sertliğini belirgin olarak arttırdığı bilindiği için, elde edilen sertlik değerleri literatürdeki çalışmalarla uyumludur (Zhang vd., 2020;Zhang vd., 2019;Jung vd., 2018). Bununla birlikte, T6 ısıl işlemi uygulanan malzemelerin ise HTPP uygulanan alaşımlara göre daha yüksek sertliğe sahip olduğu bildirilmiştir (Kalyon & Özyürek, 2017;Rahman vd., 2018;Iwaszko & Kudła, 2020). T6 yaşlandırma ısıl işlemi uygulanan alaşımlarda ikinci faz çökeltilerin tane sınırlarında yoğun ve sürekli dağılım sergilemektedir (Li vd., 2008).…”

Effect of Welding Parameters on Mechanical Properties and Microstructure of Friction Stir Welded AA7075-T651 Aluminum Alloy Butt Joints

“…Among the aluminum alloys used in the aircraft and military industries, AA7075-T651 alloy has one of the highest strength parameters [ 1 ]. The alloy is used as a construction material for stringers, wing ribs, missile parts, etc., due to its very high load carrier capacity with relatively low density (2.81 g/cm 3 ) [ 2 , 3 ]. In terms of joining components made of 7075, the most common method is riveting [ 4 ].…”