Investigating the Roles of Horizontal Solidification and Heat Treatment Process Parameters in 6201 Alloy: Thermal, Microstructure, Electrical, Mechanical, and Cold-Rolling Analysis

Abstract This study investigates the combined influence of horizontal directional solidification and subsequent T6 heat treatment on the microstructural evolution and the resulting electrical and mechanical properties of an Al-6201 alloy. Unsteady-state horizontal solidification was performed using a water-cooled mold system, enabling real-time thermal mapping during solidification. The acquired thermal data were used to determine the solidification parameters, including growth rate (V L ), cooling rate (T R ), and local solidification time (t SL ). Following solidification, the alloy was subjected to a T6 heat treatment consisting of solution at 530 °C for 3 h, water quenching at room temperature, and artificial aging at 200 °C for 2.5 h. Variations in T R promoted a macrostructural transition from columnar to equiaxed grains and refinement of the Al-rich dendritic matrix. Finer secondary dendrite arm spacing (λ2) contributed to increased hardness by hindering dislocation mobility. After the T6 treatment, precipitation hardening improved mechanical performance, resulting in a 51% increase in hardness and a 65% rise in ultimate tensile strength. The processed alloy achieved a tensile strength of 320.48 MPa, an electrical resistivity of 33.6 nΩ m, and an electrical conductivity of 51.2% IACS, evidencing a superior balance between strength and conductivity.