Thixoforging of Al–3.8% Si alloy recycled from aluminum cans

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 607; pp. 219 - 225
• Main Authors: Reis, Angelo Antônio, de Oliveira, José Roberto, de Oliveira, Rodrigo Marques, Vieira, Estéfano Aparecido
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 23.06.2014; Elsevier
• Subjects: Aluminum base alloys; Al–Si; Applied sciences; Automotive components; Cans; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Forming; Heat treatment; Intermetallic compounds; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Other heat and thermomechanical treatments; Physics; Production techniques; Recycle; Recycled; Rolling; Semi-solid; Semi-solid processing; Thermomechanical treatment; Thixoforging; Thixoforming; Treatment of materials and its effects on microstructure and properties; Weight reduction; Al–Si; Semi-solid; Thixoforming; Recycle; Heat treatment; Molten state; Water quenching; Ageing; Rolling; Mechanical properties; Forming; Semi solid state; Tensile strength; Forging; Solution heat treatment; Morphology; Automobile industry; Silicon; Microstructure; Al-Si; Strain induced melt activating process; Elongation (mechanics); Thermomechanical treatment
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.03.129

Thixoforging is an offshoot of the thixoforming process and consists of shaping a partially molten alloy into a die similarly as in a conventional forging process. However, thixoforging is carried out in solid fractions higher than 0.5 (1>fs>0.5). The aim of this work was to develop a new Al–Si alloy suitable for forming processes in the semi-solid state (SS) from recycled aluminum cans with the addition of commercially pure silicon. In this study, a new recycled aluminum alloy was created from aluminum cans with 3.8% of Si. An important aspect in the SS process is the globular microstructure, which confers relevant mechanical properties when compared to the same alloy with a dendritic morphology. The new alloy was preconditioned by thermomechanical heat treatment (THT) similar to a well-known thermomechanical method, the strain-induced melt-activation (SIMA). Samples were solution heat-treated at 530°C for 4h, quenched in water, and rolled at 350°C. The influence of the solid fraction and of the soaking time in semi solid state before thixoforging on the strength behavior of the thixoforged parts was evaluated. For all thixoforged specimens, solution heat-treatment followed by artificial aging (T6) was performed. The technique allowed us to obtain parts with tensile strength up to 334MPa and maximum elongation of 14%. These results are consistent with other thixoformed alloys obtained from processes that use raw materials with higher purity and they show, in a practical way, that it is possible to create recyclable alloys for applications in the automotive industry.