Hot Extrusion Enhanced Homogenization of Microstructure in a Spray Deposition Aluminum Alloy

Xiaofei Sheng,Yong Yang,Kai Li,Yu Liu,Wenke Wu,Yifan Zhao,Guoai He,Hongchun Yu

doi:10.3390/met10020263

Xiaofei Sheng, Yong Yang + Show 6 more

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https://doi.org/10.3390/met10020263

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Abstract

Homogeneous heat treatment serves the significant roles in eliminating the segregation and tuning the microstructure of alloy ingot. It usually cost tremendous power and time to achieve a homogeneous microstructure for aluminum alloys. In this article, the hot extrusion was directly introduced on the spray deposited aluminum alloy 7055 ingot before performing heat treatment to explore the newly feasible homogeneous routine. Equiaxed grains without dendrites or PPB were obtained in our current parameters of spray deposition, which allowed the as-deposited alloy to be deformed without being subjected to pre-homogeneous heat treatment. Significant amount of stored energy was produced during hot extrusion at 420 °C with area reduction ratio of 6.25, which effectively promoted the homogeneity of microstructure and reduced significantly the heat treatment time. A newly feasible short routine, heat treatment at 450 °C /6 h + 470 °C/1 h following the hot extrusion, proved capable of obtaining a homogeneous microstructure for the spray deposited aluminum alloy 7055.

Highlights

The rapid development of the aerospace industry required aluminum alloys to possess increasingly excellent combinations of mechanical properties and corrosion resistance
40 to 70 based output ofIn data. no no obvious preferential orientation was found in the spray deposited ingot, indicating the direction of orientation was found in the spray deposited ingot, indicating the direction of recrystallization during preferential orientation was found in the spray deposited ingot, indicating the direction of recrystallization during the spray deposition is random, which is consistent with previous reports
This article focused on an investigation of the homogeneity of microstructure in a spray deposited aluminum alloy 7055

Summary

Introduction

The rapid development of the aerospace industry required aluminum alloys to possess increasingly excellent combinations of mechanical properties and corrosion resistance. The macro segregation formed in the as-cast 7055 ingot made this alloy more inclined to suffer cracking during the processes of casting and the subsequent hot deformation [4]. Metals 2020, 10, 263 macro segregation could be improved by long-time homogenization heat treatment after casting, but it took tremendous power and time to achieve a uniform distribution of elements. The cast billet cannot be directly deformed due to the existence of macro segregation and casting defects, i.e., voids, concentration of elements, which would lead to the occurrence of cracks if not controlled properly. The as-cast aluminum alloy 7055 was usually subjected to homogeneous heat treatment at 46–47 ◦ C for 24 h before deformation [6]

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