Tensile Properties and Deformation Behaviors of a New Aluminum Alloy for High Pressure Die Casting

Peng Zhang¹，Zhenming Li¹，Baoliang Liu²，Wenjiang Ding¹

1. National Engineering Research Center of Light Alloys Net Forming and State Key Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University2. National Engineering Research Center of Light Alloys Net Forming

摘 要：Effects of natural aging and test temperature on the tensile behaviors have been studied for a highperformance cast aluminum alloy Al–10Si–1.2Cu–0.7Mn. Based on self-strengthening mechanism and spheroidization microstructures, the alloy tested at room temperature（RT） exhibits higher 0.2% proof stress（YS） of 206 MPa, ultimate tensile strength（UTS） of 331 MPa and elongation of 10%. Increasing aging time improves the YS and UTS and reduces the ductility of the alloy. Further increasing aging time beyond72 h does not signi?cantly increase the tensile strengths. Increasing test temperature signi?cantly decreases the tensile strengths and increases the ductility of the alloy. The UTS of the alloy can be estimated by using the hardness. The Portevin–Le Chatelier effect occurs at RT due to the interactions between solid solution atoms and dislocations. Similar behaviors occurring at 250 °C are attributed to dynamic strain aging mechanism. Increasing aging time leads to decrease in the strain-hardening exponent（n） value and increase in the strain-hardening coe?cient（k） value. Increasing test temperature apparently decreases the n and k values. Eutectic phase particles cracking and debonding determine the fracture mechanism of the alloy. Final failure of the alloy mainly depends on the global instability（high temperature, necking） and local instability（RT, shearing）. Different tensile behaviors of the alloy are mainly attributed to different matrix strengths, phase particle strengths and damage rate.

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