Effect of Two-Stage Homogenization Heat Treatment on Microstructure and Mechanical Properties of AA2060 Alloy

Guangjie Guangjie,Fei Fei,Lingfei Lingfei,Lin Lin,Chaoyang Chaoyang

doi:10.3390/cryst11010040

Guangjie Guangjie, Fei Fei + Show 3 more

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https://doi.org/10.3390/cryst11010040

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Abstract

The microstructure evolution of AA2060 Al alloy containing Li during two-stage homogenization treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), mechanical properties and Vickers micro-hardness test methods. The results demonstrate that severe precipitation of θ(Al2Cu) and S(Al2CuMg) phase existed in the as-cast alloy, especially in the center position. Cu elements were concentrated at grain boundary and gradually decreased from the boundary to the interior. Numerous eutectic phases of θ(Al2Cu) and S (Al2CuMg) containing Zn and Ag elements were segregated at grain boundaries. The overheating temperature of the as-cast alloy is 497 °C. After two-stage homogenization treatment, the θ(Al2Cu) and S (Al2CuMg) in the surface, middle and center positions were completely dissolved into the matrix, thus achieved uniform homogenization effect. Moreover, water cooling could prevent the precipitation after homogenization, which provided good performance of the studied alloy. The optimum two-stage homogenization treatment of AA2060 alloy was 460 °C/4 h + 490 °C/2 4 h. The homogenization kinetic analysis was discussed as well.

Highlights

The third-generation of Li-containing aluminum alloys AA2060 was registered at the American Aluminum Association in 2011 and replaces the traditional 2X24 series alloys
(Chongqing, China) The material used in this work was alloy AA2060 (Al-3.8Cu-0.3Mn0.8Mg-0.4Zn-0.13Zr-0.7Li-0.4Ag with Fe, Si, Ti less than 0.1, in wt.%), which was direct chill cast to approximate dimensions of 300 × 1200 × 4000 mm3
It was known that the inhomogeneity of the chemical composition and microstructure of the ingots can be eliminated by homogenization treatment

Summary

Introduction

The third-generation of Li-containing aluminum alloys AA2060 was registered at the American Aluminum Association in 2011 and replaces the traditional 2X24 series alloys. The material is mainly used in the manufacture for aircraft fuselage and lower wing skin, and it is an important candidate material for the lightweight manufacturing of aircraft in China [1,2] As it is latest developed and registered by Alcoa USA, there are limited reports about AA2060 compared to other Al alloys containing Li. So far, researchers mainly focus on the evolution of the microstructure during its thermal deformation, hot workability, and weldability together with its mechanical properties [3,4,5,6]. Researchers mainly focus on the evolution of the microstructure during its thermal deformation, hot workability, and weldability together with its mechanical properties [3,4,5,6] These studies have accumulated a large amount of data for the basic research of this alloy; there are few reports on the homogenization treatment process of AA2060. Wang et al [7] and Teng et al [8] studied the two-stage homogenization treatment process of Li-containing Al alloys 2050 and 20X0, respectively

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Conclusion