Effect of Zn/Mg/Cu Additions on Hot Cracking Tendency and Performances of Al-Cu-Mg-Zn Alloys for Liquid Forging

Abstract

During the process of liquid forging, a host of hot cracking defects were found in the Al-Cu-Mg-Zn aluminum alloy. Therefore, mechanical tests and analyses by optical microscope, scanning electron microscope, and X-ray diffraction were performed to research the influences of zinc, magnesium, and copper (three main alloying elements) on hot cracking tendency and mechanical properties. It was concluded that all the three alloying elements exerted different effects on the performances of newly designed alloys. And the impact of microstructures on properties of alloys was stronger than that of solution strengthening. Among new alloys, Al-5Cu-4.5Mg-2.5Zn alloy shows better properties as follows: σb=327 MPa, δ=2.7%, HB=107 N/mm², and HCS=40.

Keywords

liquid forging / Al-Cu-Mg-Zn alloys / mechanical properties / hot cracking tendency

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