Compound fabrication technology of semi-solid billet of Al-Si alloy based on SIMA method

Based on SIMA, the Al-Si alloy semi-solid billets were successfully fabricated by means of strain inducement and isothermal treatment for A1Si9Mg poured in the range of near-liquidus. Through orthogonal test, the effects of combination action of near-liquidus casting, strain inducement and isothermal treatment on the morphology of primary a-Al phase of AlSi9Mg close to eutectic point were investigated, and the optimal match relation between the processing parameters of solidification, deformation parameters of strain inducement, processing parameters of isothermal treatment and microstructure parameters of semi-solid alloy was established. The results indicate that compared with the single near-liquidus casting or SIMA, the microstructure of primary a-Al phase in AlSi9Mg alloy prepared by compound fabrication process is more homogeneous, with more globular and finer particles, which has average grain size of 40-50 pm and shape factor of greater than 0.75. After holding at 605 deg C for 30-40 min under a certain cooling rate, increased deformation volume in SIMA benefits the refinement of the grain and, the improvement of the morphology for primary phase.