High Formability Al - Mg - Si Alloy

Al-Mg-Si alloys modified by Al-10Sr master, fined by Al-5Ti-1B were prepared by adjusting the alloy components.Bars produces and profiles in different shapes were achieved after smelting, casting, extruding and plastic processing treatments. The microstructures of Al-10Sr master,Al-5Ti-1B finer,and the evolution rules of the microstructures and properties of the alloys with different heat-treatment have been investigated by means of hardness measurement, mechanical properties test, tube bending test,optical microscopy(OM),X-ray diffraction (XRD), electronic microscopy analysis (SEM). Several conclusions can be summarized as follows:1) The micro structure of Al-10Sr modifier include a-Al matrix, Al4Sr phase in thin strip shape, and AlSrO phase in block shape,the microstructure of Al-5Ti-1B finer is consist of α-Al matrix, TiAl3phase in block shape and dispersed TiB2phase.2) The microstructure of Al-Mg-Si-Sr alloy modified by Al-10Sr master contains α-Al matrix, AlMgFeSi phase in rod shape, the mechanical properties after T6treatment is σb=259MPa, σ0.2=227MPa, elongation percentage=13%3) The as-cast microstructure of Al-Mg-Si-Ti-Sr alloy modified by Al-10Sr master and fined by Al-5Ti-1B, contains dendritic-network structure,with AlMgFeSi phase and AlFeSi phase distributed in the grain boundary and internal grain, the mechanical properties of hollow profiles, which perform a satisfied formability, after T6treatment σb,σ0.2and δ are261MPa,225MPa, and14%.4) The as-cast microstructure of Al-Mg-Si-Ti-Sr-Mn alloy contains the distribution of AlFeSi phase in the grain boundary, which owns the smaller recrystallization grain than other alloys, yet qualified properties can not be achieved until the solution treatment and aging heat-treatment.