Heat Treatment of High Pressure Die Cast AlSi7MgMn Alloy

Author of the article:YANG Jie1,2, ZHAO Yue1 , YAN Kangkang3 , CHEN Yuzeng1 , LIU Feng1

Author's Workplace：1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. China Automotive Lightweight Technology (Jiangsu) Co., Ltd., Yangzhou 225000, China; 3. Technology Center of Shaanxi Automobile Holding Group Co., Ltd., Xi'an 710200, China

Key Words：cast aluminum alloy; melt cooling rate; solidification; heat treatment; microstructure and mechanical properties

Abstract：High pressure die cast AlSi7MgMn alloy was annealed and artificially aged, and the evolution of its microstructure and properties was studied. The results show that annealing and artificial aging treatment can precipitate nano Si particles in the aluminum matrix, so that dislocations are entangled and stored in the aluminum grains during the deformation process, and the ability of plastic deformation of the material is improved. After artificial aging, the precipitated β″ phases in aluminum matrix can significantly hinder the movement of dislocation and produce precipitation strengthening effect. Compared with the die-cast state, the two-step heat treatment process can increase the yield strength of the alloy to 150 MPa, increased by 25%, and the elongation after fracture of the alloy is 9%, not decreased.