Microstructure and High-Temperature Fracture Mechanism of Continuously Cast and Directly Rolled 2017 Al-Cu Alloy

Using lightweight materials is essential for addressing the energy crisis and mitigating environmental pollution. This study investigates the fabrication of 2017 aluminum alloy wire rod coils using continuously cast and directly rolled (CCDR) technology. CCDR is an efficient process that streamlines production, shortens cycle times, reduces costs, and minimizes energy consumption. This research aimed to improve the mechanical properties of CCDR-manufactured 2017 aluminum alloy under elevated temperatures and repetitive heating-cooling cycles. Experiments were conducted to evaluate the effects of various heat treatment parameters on the alloy’s microstructure, mechanical strength, and crack growth, both in its raw state and after cold rolling. The findings revealed that a solution treatment at 570 °C followed by aging enhanced the alloy's strength and induced dynamic strain aging (DSA). However, high-temperature solution treatment also resulted in grain coarsening and precipitation, negatively impacting the alloy's fatigue life. High-temperature tensile tests showed that the alloy retained its strength as the temperature increased, with tensile strength exceeding 200 MPa at 200 °C. During thermal fatigue testing, ductility gradually decreased after 500 heating-cooling cycles. The Al₂Cu precipitates and the texture produced by the CCDR process contributed to the 2017 aluminum alloy's excellent mechanical properties at elevated temperatures and under repeated thermal cycling. This research is significant as it offers new insights into the microstructural evolution and fracture mechanisms of CCDR-manufactured 2017 aluminum alloy, thereby providing valuable knowledge for producing aerospace-grade aluminum alloys through innovative processing techniques.