Strength and wear resistance enhancement of AlSn20Cu alloys through grain refinement and Sn segregation inhibition

During the gravity casting (GC) process, Sn segregation frequently occurs, which is generally detrimental to the strength and wear resistance of AlSn20Cu alloys. The continuous casting (CC) and continuous casting direct rolling (CCDR) processes were used to minimize Sn segregation in AlSn20Cu alloys. The results demonstrated that, with increasing cooling rate, the CC process significantly promoted grain refinement, reduced Sn segregation and pore formation, compared to the GC process. Consequently, the density and mechanical properties of the CC specimen were enhanced. After the rolling process, the grain size and Sn segregation were further reduced, leading to additional improvements in density and mechanical properties. The ultimate tensile strength of the CCDR specimen reached 133.8 MPa, the yield strength reached 57.2 MPa, and the elongation reached 20.3%, respectively. Compared with GC specimen, the ultimate tensile strength was increased by 98.2%, the yield strength was increased by 29.1%, and the elongation was increased by 170.7%. The enhanced resistance to plastic deformation in the CCDR specimen reduced the average friction coefficient and shifted the wear mechanism from adhesive wear to abrasive wear. The uniform distribution of the Sn phase in the CCDR specimen improved the integrity of the lubricating film, thereby enhancing the friction stability and reducing the volumetric wear rate. • Sn segregation can be effectively inhibited by increasing the cooling rate. • The rolling process can promote the further uniform distribution of the Sn phase. • Rapid cooling and rolling processes can effectively achieve grain refinement. • Grain refinement brings about a synergistic increase in strength and elongation. • Wear resistance is improved through optimized Sn distribution and grain refinement.