Static Mechanical Property Criterion Determined under Different Extent of Hot Crack Index of High-Strength Aluminium Autogenous Laser Welds

Abstract

Nowadays, vehicle electrification is growing at a fast pace due to stringent environmental regulations on carbon emissions in North America. The manufacturing of E-mobility battery components such as enclosures evolves at the same trend and many new design concepts are put in place. As health and safety in electric vehicles are taken very seriously by OEMs, the enclosures are still heavy but are likely to become more lightweight in years to come, using high-strength aluminium alloys as one of the potential solutions, as weight directly affects the admissible range. In this paper, four (4) different aluminium wrought alloys (AA6061, AA6010, AA7020 S and AA7075) were autogenously laser-welded using various parameters and inspected through 2D X-ray tomography. A hot crack index (HCI), using optical microscopy, was defined in order to quantify the internal extent of hot cracks. Static mechanical butt joint tensile tests were provided to dictate a mechanical property criterion regarding the extent of HCI. This revealed that uniform elongation is a good predictor of the extent of HCI in terms of static mechanical behavior. These findings could eventually be used to define a threshold value toward a safe number of hot cracks in laser welds.

Keywords

• high-strength aluminium
• laser welding
• hot cracking