Sc-Containing Al–Si–Mg (6xxx) Alloys for Automotive Extrusions

Our work focuses on improving the manufacturability and performance of Al–Si–MgAl-Si-Mg 6xxx6xxx series alloysAlloys for structural automotiveAutomotive components. ScandiumScandium is the most potent strengthening element in aluminum alloysAluminum alloys but interactions between Sc and Si have limited the use of Sc in high Si-containing alloysAlloys (6xxx6xxx). We demonstrate modified heat treatmentHeat treatment schedules for precipitation of potent Sc-containing dispersoids, which are stable during extrusionExtrusion and processingProcessing. Trace scandiumScandium additions increase strength and tear resistance in lightly alloyed 6xxx6xxx alloysAlloys and reduce extrusionExtrusion and heat-treating costs relative to alloysAlloys with comparable strength and tear resistance. In one example, an Al–0.5Si–0.5Mg alloyAlloys with an 0.09 wt% Sc addition increased T6 yieldYield strength from 276 to 372 MPa with ductility only decreasing from 21 to 18%. The role of castingCasting and homogenizationHomogenization on precipitation of these stable Sc-containing dispersoids will be discussed.