Microstructure, mechanical properties and deformation characteristics of Al-Mg-Si alloys processed by a continuous expansion extrusion approach. (30th July 2021)

• Record Type: Journal Article
• Authors: Lu, Ruiqing; Zheng, Shuwei; Teng, Jie; Hu, Jiamin; Fu, Dingfa; Chen, Jianchun; Zhao, Guodong; Jiang, Fulin; Zhang, Hui
• Is Part Of: Journal of materials science & technology. Volume 80(2021)
• Page Start: 150
• Page End: 162
• Publication Date: 2021-07-30
• Subjects: Al-Mg-Si alloy -- Continuous expansion extrusion forming -- Microstructure -- Mechanical property -- Finite element analysis; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.11.055
• Languages: English
• ISSNs: 1005-0302

Abstract

Graphical abstract: Highlights: Double pass continuous extrusion expansion forming (CEEF) was proposed to expand the size of Al-Mg-Si alloy rod. The strength and ductility of aged Al-Mg-Si alloy with double pass CEEF was synchronously improved. The precipitation kinetics was remarkable affected by the residual dislocations and cooling methods after CEEF process. Grain size of CEEF processed Al-Mg-Si alloy was refined remarkably by CDRX and GDRX mechanisms. The special microshear bands were introduced which could accelerate dynamic recrystallization. Abstract: In the present work, a double-pass continuous expansion extrusion forming (CEEF) process was proposed for an Al-Mg-Si alloy, in which the diameter of rods was gradually expanded. The microstructural evolution, mechanical properties and deformation characteristics were investigated by utilizing microstructural observations, mechanical testing and a finite element method coupled with a cellular automata model. The results showed that the strength and ductility of the double-pass CEEF processed Al-Mg-Si alloys were improved synchronously, especially in artificially aged alloys. The grain size of the processed Al-Mg-Si alloy rods was refined remarkably by continuous dynamic recrystallization (CDRX) and geometric dynamic recrystallization (GDRX), and the homogeneity of microstructure was gradually improved with increasing number of processing passes. The artificially aged alloy processed with double-pass CEEF and water quenching contained fine (sub)grains and high-density dislocations, which resulted in more needle-shaped β " precipitates and a larger precipitate aspect ratio than the as-received and air-cooled CEEF alloys owing to the different precipitation kinetics. The severe cumulate strain and microshear bands were found to accelerate CDRX and GDRX for grain refinement between adjacent positions of the parabolic metal flow due to the special temperature characteristics and large shear straining during the CEEF process.