Rheo-Cast Microstructure and Mechanical Properties of AM60 Alloy Produced by Self-Inoculation Rheo-Diecasting Process

Bo Xing,Yuandong Li,Guangshan Hu,Chengli Tang,Junyan Feng

doi:10.3390/met6030069

Bo Xing, Yuandong Li + Show 3 more

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https://doi.org/10.3390/met6030069

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Journal: Metals	Publication Date: Mar 18, 2016
Citations: 4	License type: CC BY 4.0

Affiliation: Jiaxing University, Lanzhou University of Technology

Abstract

Rheo-forming is becoming the choice for production of high quality parts with diminished defects and fine integrity. In this paper, the novel self-inoculation rheo-diecasting (SIRD) process, in which semisolid slurry is produced by mixing two precursory solid and liquid alloys and subsequently pouring them through a multi-stream fluid director, has been proposed. Microstructural characteristics of AM60 alloy slurry and the microstructure and mechanical properties of rheo-diecasting AM60 samples were investigated. Quenching experiments reveal that the slurry microstructure of AM60 was well refined to irregular α-Mg particles with the average size of approximately 20–40 μm after pouring with the self-inoculation process, and these particles were evolved to globular and coarse morphology while continuously keeping in semisolid state. After rheo-diecasting, the microstructure of the sample was dominated by fine primary α-Mg globules accompanied with tiny secondary α-Mg particles while the sample from conventional liquid die casting was characterized by developed dendrite and porosity. Microscopic analysis indicates that there are three stages of remaining liquid solidification in die cavity in SIRD: α-Mg nucleation and growth on primary α-Mg surface, α-Mg nucleated independently in liquid, and, finally, formation of skeleton devoiced eutectic. Due to diminished porosity and hot tearing, tensile strength and elongation of SIRD samples were increased by 12.9% and 35.3%, respectively, compared to a conventional liquid die casting sample.

Highlights

Rheo-diecasting (RD), an alternative semisolid forming technology for shaping complex thin-wall parts with high integrity, has been attracting considerable interest during the past several years [1,2,3].Because the starting material contains a certain fraction of a solid phase, the die filling process in RD presents as laminar, so the porosity can be readily reduced, the components can be further strengthened by heat treatment [4]
Commercial AM60 alloy was used as the experiment material
Preparation of Semisolid AM60 Alloy by Self-Inoculation

Summary

Introduction

Rheo-diecasting (RD), an alternative semisolid forming technology for shaping complex thin-wall parts with high integrity, has been attracting considerable interest during the past several years [1,2,3].Because the starting material contains a certain fraction of a solid phase, the die filling process in RD presents as laminar, so the porosity can be readily reduced, the components can be further strengthened by heat treatment [4]. Compared with thixo-forming, the RD process is relatively lower in cost and higher in efficiency because the slurry is produced from melt cooling, rather than billet production and followed by remelting. This technology has promising application prospects in the fields of transportation and household appliances. The key to RD is to produce the semisolid slurry that contains fine and spherical solid grains in cooling of alloy melt. In order to meet this requirement, some processes that involve stirring the melt under mechanical or electromagnetic forces have been developed during the past several

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Discussion

Conclusion