Evolution of Microstructure and Mechanical Properties in a Single-Stage Aged 7075 Aluminum Alloy Pulse Variable Polarity Plasma Arc Welded Joint

Abstract

A 7075 aluminum alloy was successfully welded by pulsed variable polarity plasma arc welding (PVPPAW) and the single-stage aging behavior of the 7075 aluminum alloy PVPPAW joint was systematically investigated. The results demonstrated that the tensile strength of the welded joints initially increased and then decreased with the increase of the single-stage aging temperature and time. After single-stage aging at 490 °C for 80 min and at 130 °C for 24 h, the tensile strength of the welded joint was 551 MPa, which was increased by 38.5% compared to the as-welded joint. Moreover, the conductivity was 25% international annealed copper standard (IACS) at room temperature, and the resistance to stress corrosion was improved. The main strengthening phases of the weld center were η′ and η phase. The average precipitate size slightly increased with the increase of the single-stage aging temperature, but no obvious change was observed with the increase of the single-stage aging time. The area fraction was initially increased and then decreased with the increase of the single-stage aging temperature and time.

Increasing the Mechanical Strength and Corrosion Resistance of Aluminum Alloy 7075 via Hydrostatic Extrusion and Aging

“…The CG T6 sample is characterized by a coarsegrained microstructure with a high density of η precipitates within the grain interiors, with additional η precipitates visible as small dots within the matrix. Similar observation of the microstructure components were found in, e.g., [24,28,29] The microstructures of the HE10 HT2 and HE8 HT2 samples are substantially deformed, which can be seen by the grain refinement, but also feature significant increases in dislocation density. Moreover, it is seen in selected area diffraction images, which are inside the TEM micrographs.…”

“…Both η and η precipitate are rich in these elements. For AA7075, these two precipitates are the major precipitates in the microstructure, as can be seen in numerous papers, e.g., [24][25][26][27].…”

Effect of pH and Concentration on Electrochemical Corrosion Behavior of Aluminum Al-7075 T6 Alloy in NaCl Aqueous Environment

“…However, it has been keener to investigate the electrochemical behavior of aluminum alloys [4] because of their extensive use in marine and aerospace applications [5,6]. For example Al7075-T6 is a light-weight aluminum alloy with unique ageing treatment being utilized in aerospace and marine applications owing to its superior mechanical properties due to precipitationhardening [7,8]. These alloy have been shown to be highly sensitive to heat treatment in terms of their microstructure and the composition (Table 1) of the matrix which is effected by the type, size and shape of the precipitates formed in different alloys [9][10][11].…”