We investigate the effect of thermal-rate treatmentThermal rate treatment (TRT) on age-hardening behavior and mechanical propertiesMechanical properties of Al–10Si–0.35Mg alloys with an extended range of Fe content. The alloys were prepared by direct-chill castingCasting for fast solidificationSolidification and then artificially aged (i.e. T5 heat treatmentT5 heat treatment). In the as-cast condition, TRT significantly reduces the size of Fe-rich intermetallicsIntermetallic with a uniformUniform distributionDistribution of intermetallicIntermetallic particles. The precipitationPrecipitation sequence in both alloys during T5 heat treatmentT5 heat treatment remains consistent, while the TRT alloy exhibits a slower precipitationPrecipitation kineticsKinetics and higher density of fine precipitatesPrecipitate. TRT alloys have higher hardness and tensile strengthTensile strength while maintaining comparable elongation to NTRT alloys. Theoretical calculations of precipitationPrecipitation strengthening also show higher values for TRT alloys, in agreement with the experimental results. In this work, underlying mechanism of melt treatments crucial for improving precipitationPrecipitation behavior and mechanical propertiesMechanical properties of Al–Si–Mg alloys are further discussed.