Influence of Torsion on Precipitation and Hardening Effects during Aging of an Extruded AZ91 Alloy

Journal Article · Mon Jul 15 04:00:00 EDT 2019 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-019-04152-6· OSTI ID:22970674

Song, Bo; Liu, Tingting ^[1]; Xin, Renlong ^[2]; Yang, Hong ^[3]; Guo, Ning ^[1]; Chai, Linjiang ^[4]; Huang, Yuanding; Hort, Norbert ^[3]

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1. Southwest University, School of Materials and Energy (China)
2. Chongqing University, College of Materials Science and Engineering (China)
3. MagIC-Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht (Germany)
4. Chongqing University of Technology, College of Materials and Engineering (China)

The effect of torsional deformation by various routes prior to artificial aging treatment on the microstructure of extruded AZ91 rods was investigated. The tension and compression properties along the extruded direction were tested to evaluate the hardening effect. The results showed that torsional deformation can largely enhance the subsequent age-hardening effect. A detailed microstructural characterization revealed that torsional deformation produced a high density of dislocations and {10-12} twins, which can promote continuous precipitation and increase the number density of the Mg{sub 17}Al{sub 12} phase. In addition, part of dislocations and the {10-12} twins were retained after aging treatment. The combination of the increased precipitation hardening by Mg{sub 17}Al{sub 12}, dislocation strengthening and refinement strengthening contributed to the high hardening effect. Moreover, the hardening effect can be further increased by tailoring the torsion route. The torsion route exhibited little influence on the age-hardening effect, while it remarkably affected the texture of the twisted AZ91 rods. Reciprocating torsion had little influence on the texture. In contrast, unidirectional torsion caused the c-axis of the texture to rotate toward the extrusion direction, resulting in a texture softening effect. Therefore, combining reciprocating torsion and aging caused a higher hardening effect than combining unidirectional torsion and aging. The detailed strengthening mechanism was analyzed and is discussed.

• OSTI ID: 22970674
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 7 Vol. 28; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGE HARDENING
AGING
ALLOYS
DISLOCATIONS
HARDNESS
PRECIPITATION HARDENING
TEXTURE
TORSION