Inhibiting weld cracking in high-strength aluminium alloys

Abstract

Cracking from a fine equiaxed zone (FQZ), often just tens of microns across, plagues the welding of 7000 series aluminum alloys. Using a multiscale correlative methodology, from the millimeter scale to the nanoscale, we shed light on the strengthening mechanisms and the resulting intergranular failure at the FQZ. We show that intergranular AlCuMg phases give rise to cracking by micro-void nucleation and subsequent link-up due to the plastic incompatibility between the hard phases and soft (low precipitate density) grain interiors in the FQZ. To mitigate this, we propose a hybrid welding strategy exploiting laser beam oscillation and a pulsed magnetic field. This achieves a wavy and interrupted FQZ along with a higher precipitate density, thereby considerably increasing tensile strength over conventionally hybrid welded butt joints, and even friction stir welds.

Impact of Arc‐Based Welding on the Microstructure Evolution and Mechanical Properties in Newly Developed Cr29.7Co29.7Ni35.4Al4Ti1.2 Multi‐Principal Element Alloy

“…[35] Its formation is common to occur in on other system such as Ni-superalloys [36,37] and in Al-alloys. [38] In the current work, no evidence of hot cracking was observed.…”

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“…In addition, the intrinsic yield strength of pure aluminium ( σ 0 = 10 MPa 41 ) must be considered. Consequently, the overall increment for yield strength can be summarized as 42 : …”

Review on laser directed energy deposited aluminum alloys

“…The aerospace industry is one of the leading drivers of AM [6][7][8][9]. With the demand to be lightweight, the proportion of Al alloy applied in aerospace structural parts and automotive fields is increasing continuously due to its excellent strength-ductility synergy, wear resistance, and thermodynamic stability [10][11][12]. In recent years, many high-strength Al alloys dedicated to AM have been developed and put into practical application [13][14][15].…”