A Novel Approach to Improve the Microstructure and Mechanical Properties of Al-Mg-Si Aluminum Alloys during Twin-Roll Casting.

Yong Li,Jiadong Li,Chen He,Di Wu,Guangming Xu,Zhaodong Wang

doi:10.3390/ma13071713

Abstract

The main purpose of this present study was to investigate the different processing conditions on the microstructure, segregation behavior of alloying elements, and mechanical properties of Al−Mg−Si alloy twin-roll cast slab prepared using a novel twin-roll casting technology. The simulation of temperature field, distribution of alloying elements, tensile properties, hardness, and conductivity were examined by a Leica optical microscope, scanning electron microscopy, energy dispersion spectroscopy, electron probe microanalysis, and tensile tests. The results indicated that when the traditional twin-roll casting method was used to produce aluminum alloy strip, there are obvious centerline segregation defects due to the deep crystallization front depth and symmetrical solidification characteristics. When the forced-cooling technology was applied in the twin-roll casting process, by virtue of the changing of crystallization front depth and crystallization front shape, the segregation defects are obviously suppressed. Suggesting that this method can significantly improve the uniformity of alloying elements in the thickness direction of the twin-roll cast slab, ultimately improve the mechanical properties of AA6022 aluminum alloy.

Highlights

Al−Mg−Si series aluminum alloy is widely used in the field of transportation due to its superior comprehensive properties, such as low density, good stamping performance, high surface quality, good corrosion resistance, and easy recycling [1,2]
Many researchers have successfully fabricated aluminum alloy strips using twin-roll casting technology with a copper roller sleeve, effect of roll casting speed, roll gap, cooling water flow rate, initial cooling water temperature, and initial temperatures of the melt were considered, and the results indicated that homogeneous microstructures and improved mechanical properties were obtained by increasing the cast rolling speed and roll gap thickness [11,12,13]
In order to study the effect of different processing conditions on the solid-solution degree of elements, we have examined the hardness in the width direction and the electrical conductivity in the alloy elements, we have examined the hardness in the width direction and the electrical conductivity thickness direction of twin-roll casting (TRC) sheets

Summary

Introduction

Al−Mg−Si series aluminum alloy is widely used in the field of transportation due to its superior comprehensive properties, such as low density, good stamping performance, high surface quality, good corrosion resistance, and easy recycling [1,2]. The conventional route of producing rolling slabs is direct chilling semi-continuous casting followed by homogenization, surface scalping, hot/cold-rolling, intermediate annealing, and heat treatment, which has the disadvantage of complex process, high cost, and material consumption [3]. Twin-roll casting technology can produce strips directly from melt and has the advantage of short process, energy saving, low cost, and better properties. The most serious disadvantage is that when the aluminum alloy with high alloy element content is produced by twin-roll casting method, because of its wide solidification range, the centerline segregation defects occurred in the casting rolling strip, which makes the twin-roll cast products crack in the subsequent processing [4]. It is urgent to develop a novel method to produce aluminum alloy of wide solidification range with fewer segregation defects and better properties, which has the prospect of engineering application

Objectives

Methods

Results

Conclusion