Underlying cause of the performance deteriorates of Al–Cu–Mg alloy via electron-beam welding and the mechanism of ultrasonic modification

Abstract

The phenomenon of joint softening often occurs in the fusion welding process of Al-Cu-Mg alloy, which predominately derives from the grain coarsening within the joint. But in this paper, it is pointed out that the decrease in the number and proportion of strengthening phases caused by element burning is also one of the causes. The mechanism of performance degradation of the joint was explained from transformation of strengthening phase. It was clarified that the ultrasonic strengthening was due to the fragmentation of surface grains and eutectic phases in the shape of continuous net along grain boundaries. The formation of subcrystals, resulting from multiplication, slip, intersection of dislocations and the interaction with the strengthening phases, further improved the surface properties. Highlights• The mechanism of performance reduction of electron beam welding Al-Cu-Mg alloy is explained.• The burning loss of magnesium element and the effect on the number and type of strengthening phases are revealed. • The strengthening mechanism of the surface modification by ultrasonic impact treatment is expounded. • The improvement of properties and the transformation of tensile fracture mode are revealed.

Study on Microstructure and Mechanical Properties of Friction Stir Welding Joints of In-Situ Al3Zr/AA6082 Particle-Reinforced Aluminum Matrix Composites

“…aluminum matrix composites have good conductivity and corrosion resistance, high specific modulus and specific strength, which are often used as structural materials for aerospace, high-speed rail and automotive industries with great demand for lightweight materials [1][2][3][4][5][6][7][8]. the melting point, thermal conductivity and linear expansion coefficient of the reinforced phase in the composites are greatly different from those of the matrix aluminum alloy, which makes the welding performance of the aluminum matrix composites very poor and the weld is easy to form holes and inclusions.…”

Microstructure and properties of vacuum electron beam welded WE43 magnesium alloy joint

“…In order to fully understand the welding performance, microstructure and mechanical properties of the joints of WE43 magnesium alloy plates, this work adopts an optimized EBW process to weld WE43 magnesium alloy plates. The welding characteristics of WE43 magnesium alloy plates were studied, and the microstructure, joint morphology and mechanical properties of the electron beam welded joint were analyzed, which provided a reference for further understanding of the relationship between the welding properties and the microstructure evolution of the magnesium alloy [7,8].…”

Microstructure Evolution and Strengthening Mechanism of Galvanized Steel/Mg Alloy Joint Obtained by Ultrasonic Vibration-Assisted Welding Process

“…With increasing demand from consumers and the environment for high fuel efficiency vehicles, as well as for the reduction of carbon dioxide emissions from vehicles, nonferrous metals, as a good substitute for traditional metal alloys, have attracted much attention [ 1 , 2 , 3 ]. Specifically, nonferrous alloys based on aluminum (Al) [ 4 ], magnesium (Mg) [ 5 , 6 ], and titanium (Ti) [ 7 ] with high specific strength, superior processability, and easy recycling have been developed and used in automobile manufacturing and aerospace fields. Over the past decade, Mg alloys have attracted considerable attention in the automotive industry because of their potential to reduce weight to achieve better fuel economy [ 8 , 9 ].…”