《Induction heating process of an Al–Si aluminum alloy for》.pdf

Journal of Materials Processing Technology 120 (2002) 355–364 Induction heating process of an Al–Si aluminum alloy for semi-solid die casting and its resulting microstructure * H.K. Jung, C.G. Kang School of Mechanical Engineering, Engineering Research Center for Net Shape and Die Manufacturing (ERC/NSDM), Pusan National University, Pusan 609-735, South Korea Accepted 10 September 2001 Abstract During induction heating, the relationship between time and temperature must be controlled exactly to obtain a homogeneous temperature distribution over the entire cross-sectional area. Because the initial solid fraction in the semi-solid die casting (SDC) process is the main parameter to achieve a homogeneous flow behavior of the liquid and solid phases and to prevent macro-segregation effects in the SDC process, an accurately controllable induction heating method must be selected for the reheating process. The purpose of this work is not just to obtain the desire solid fraction, generally about 50%, but also to ensure the optimal induction heating conditions of A356 alloy to reduce the temperature gradient of a 76 mm diameter 90 mm length billet and to obtain a fine globular microstructure without grain coarsening (resulting microstructure). This work shows that, in the case of a three-step reheating process for the SDC process, the final holding time is the most important factor to maintain a fine globular microstructure without grain coarsening. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Induction heating process; Semi-solid die casting; R