Effect of Cu addition on overaging behaviour, room and high temperature tensile and fatigue properties of A357 alloy
(1. Department of Industrial Engineering (DIN), Alma Mater Studiorum, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy;
2. Ducati Motor Holding, Via Cavalieri Ducati Antonio 3, 40132 Bologna, Italy;
3. Department of Materials and Manufacturing, School of Engineering, J？nk？ping University, Gjuterigatan 5, 55111 J？nk？ping, Sweden;
4. Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum, University of Bologna, Viale Risorgimento 4, Bologna, Italy)
2. Ducati Motor Holding, Via Cavalieri Ducati Antonio 3, 40132 Bologna, Italy;
3. Department of Materials and Manufacturing, School of Engineering, J？nk？ping University, Gjuterigatan 5, 55111 J？nk？ping, Sweden;
4. Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum, University of Bologna, Viale Risorgimento 4, Bologna, Italy)
Abstract: The aims of the present work are to evaluate the overaging behaviour of the investigated Cu-enriched alloy and to assess its mechanical behaviour, in terms of the tensile and fatigue strength, at room temperature and at 200 °C, and to correlate the mechanical performance with its microstructure, in particular with the secondary dendrite arm spacing (SDAS). The mechanical tests carried out on the overaged alloy at 200 °C indicate that the addition of about 1.3 wt.% Cu to the A357 alloy enables to maintain ultimate tensile strength and yield strength values close to 210 and 200 MPa, respectively, and fatigue strength at about 100 MPa. Compared to the quaternary (Al-Si-Cu-Mg) alloy C355, the A357-Cu alloy has greater mechanical properties at room temperature and comparable mechanical behaviour in the overaged condition at 200 °C. The microstructural analyses highlight that SDAS affects the mechanical behaviour of the peak-aged A357-Cu alloy at room temperature, while its influence is negligible on the tensile and fatigue properties of the overaged alloy at 200 °C.
Key words: A357 alloy; C355 alloy; Al-Si-Cu-Mg casting alloy; tensile property; fatigue behaviour; high temperature; overaging