Weldability of Aluminum Alloys

Abstract

Weldability is a function of three major factors: base material quality, welding process, and design. This article focuses on base-metal weldability of aluminum alloys in terms of mechanical property degradation in both the weld region and heat-affected zone, weld porosity, and susceptibility to solidification cracking and liquation cracking. It provides an overview on welding processes, including gas metal arc welding, gas tungsten arc welding, resistance spot and seam welding, laser beam welding, and various solid-state welding processes. A review on joint design is also included, mainly in the general factors associated with service weldability (fitness). The article also provides a discussion on the selection and weldability of non-heat-treatable aluminum alloys, heat treatable aluminum alloys, aluminum-lithium alloys, and aluminum metal-matrix composites.

Solidification cracking susceptibility of quaternary aluminium alloys

“…Although 5356 Al can be used to weld some 7xxx series Al alloys, such as 7039 Al, it is not suitable for welding 2090 Al [32]. However, it has been demonstrated that 2319 Al (Al-6.3Cu) is an appropriate filler metal for welding 2090 Al [30,31]. Figure 14…”

“…Figure 8 shows the calculated crack susceptibility of Al-Zn-Mg-Cu alloys using 7039 Al (Al-4Zn-2.8Mg-0.1Cu) and filler metal 5356 Al (Al-5.0Mg-0.1Cu) as examples. 7039 Al is very crack susceptible but can be welded with filler metal 5356 Al [30]. Again, the dilution is 20% in the calculation of the weld composition.…”

Coaxial Wire Laser-based Additive Manufacturing of AA7075 with TiC Nanoparticles

“…On the other hand, gas pores can appear due to several reasons. First, liquid aluminium can quickly dissolve high amounts of hydrogen, and because the solubility rapidly decreases during solidification, most of this hydrogen precipitates as gas and generates pores [19,20]. Second, trapped gases generated for the evaporation of low-boiling-point elements zinc and magnesium (907°C and 1090°C, respectively) [21].…”

“…As dendrites grow bigger, they collide with adjacent ones, creating boundaries that are occupied by the constituents with lower solidification temperatures, still in liquid state. Solidification contraction produces tensile forces that can be strong enough to tear the liquid film, and if there is not enough melt phase to backfill and 'heal' these voids, solidification cracking will occur [18,19,25]. On the other hand, liquation cracking occurs because of reheating of previously solidified layer.…”