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Microstructures of an AZ61 wrought magnesium alloy fabricated by a novel SPD process using thermomechanical simulation

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Veröffentlicht/Copyright: 24. Dezember 2015
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Materials Testing
Aus der Zeitschrift Materials Testing Band 58 Heft 1

Abstract

Extrusion-shear (ES), a novel severe plastic deformation (SPD) method which includes initial forward extrusion and a subsequent one step shearing process, has been developed to fabricate fine grained AZ61 Mg alloys in a Gleeble 1500D thermomechanical simulator for the first time. The effects of the ES process on the grain refinement of an as cast magnesium alloy were investigated at different extrusion speeds and the microstructures of the as processed billet and rods were investigated at right, central and left positions. It was found that the extrusion force caused by the ES process at 5 mm × s−1 is about 5 times of that caused at an extrusion speed of 1 mm × s−1. Besides, the increase of extrusion speed could improve the deformation stress. The ES extrusion causes serve plastic deformation and improves the dynamic recrystallization during the process. The results confirmed that the ES process can be used to refine the grains effectively and to produce serve plastic deformation. The microstructural investigation showed that grain sizes are finer in the bottom parts than in the other parts of the rod.

Kurzfassung

Extrusion-Shear (ES), eine hochplastische Verformungsmethode (Severe Plastic Deformation (SPD) method), die anfängliche Vorwärts-Extrusion und nachfolgend einen einstufigen Verformungsprozess beinhaltet, wurde entwickelt, um feinkörnige AZ 61 Magnesiumlegierungen erstmalig in einem thermomechanischen Simulator (Gleeble 1500D) herzustellen. Die Auswirkungen des ES-Prozesses auf die Kornfeinung der gegossenen Magnesiumlegierung wurden bei verschiedenen Extrusionsgeschwindigkeiten untersucht und die Mikrostrukturen der ES-hergestellten Barren und Stangen wurden auf der rechten Seite, in der Mitte und auf der linken Seite beobachtet. Es stellte sich heraus, dass die Extrusionskraft infolge des ES-Prozesses bei 5 mm × s−1 etwa das Fünfache derjenigen bei 1 mm × s−1 beträgt. Daneben kann ein Anstieg der Extrusionsgeschwindigkeit die Deformationsspannung verbessern. Die ES-Extrusion ruft eine hohe plastische Deformation hervor und verbessert die dynamische Rekristallisation während des Prozesses. Die Ergebnisse bestätigen, dass der ES-Prozess die Körner effektiv verfeinert und eine hohe plastische Verformung bewirkt. Die mikrostrukturelle Untersuchung zeigt, dass die Korngrößen in den unteren Bereichen der Stangen feiner als in den anderen Bereichen waren.

§Correspondence Address, Prof. Dr. Hong-Jun Hu, College of Material Science and Engineering, Chongqing University of Technology, Chongqing 400050, China. E-mail:

Hong-Jun Hu received his BS and MS degrees from Hubei University of Technology, Wuhan City, Hubei Province, China in 2003 and his PhD from Chongqing University, China in 2010. He has co-authored four books, and has over 30 publications on various aspects of casting, extrusion and special extrusion. He is also an owner of patents in the field of formation technologies for magnesium alloy. Currently, he is Associate Professor at Chongqing University of Technology, China.

Zhao Sun, ZhaiYe Zhai and JunLin Dai are research assistants at College of Material Science and Engineering, Chongqing University of Technology, China.

Xiaoqing Wang is a research assistant at the Department for Mechanical Engineering, University of Alabama, USA. His research interests include characterization and mechanical properties of super alloys.

Mingbo Yang is Professor at College of Material Science and Engineering, Chongqing University of Technology in China. He received his PhD from Chongqing University, China in 2001. He has coauthored ten books, and has over 80 publications.

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Published Online: 2015-12-24
Published in Print: 2016-01-05

© 2016, Carl Hanser Verlag, München

Artikel in diesem Heft

  1. Inhalt/Contents
  2. Contents
  3. Fachbeiträge/Technical Contributions
  4. Quantification of vanadium precipitates in HSLA steel by synchrotron X-ray absorption spectroscopy (XAS)
  5. Optimization of the wear behavior of uncoated, TiN and AlTiN coated cold work tool steel 1.2379 using response surface methodology
  6. Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy
  7. Probability of detection of minute defects by ultrasonic automated testing equipment in view of Bayesian inference
  8. Parameters in lock-in thermography of CFRP laminates
  9. Effect of tool material on microstructure and mechanical properties in friction stir welding
  10. Microstructures of an AZ61 wrought magnesium alloy fabricated by a novel SPD process using thermomechanical simulation
  11. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70
  12. Effects of post-curing on the thermo-mechanical behavior and the chemical structure of highly filled phenolic molding compounds
  13. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing
  14. Deep micro-hole drilling of Hardox 500 by electro-discharge machining
  15. Optimization of thin-wall structures using hybrid gravitational search and Nelder-Mead algorithm
  16. Structural design of vehicle components using gravitational search and charged system search algorithms
  17. Electrical resistivity and strength properties of sodium hydroxide contaminated soil solidified with cement
https://doi.org/10.3139/120.110817

Artikel in diesem Heft

  1. Inhalt/Contents
  2. Contents
  3. Fachbeiträge/Technical Contributions
  4. Quantification of vanadium precipitates in HSLA steel by synchrotron X-ray absorption spectroscopy (XAS)
  5. Optimization of the wear behavior of uncoated, TiN and AlTiN coated cold work tool steel 1.2379 using response surface methodology
  6. Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy
  7. Probability of detection of minute defects by ultrasonic automated testing equipment in view of Bayesian inference
  8. Parameters in lock-in thermography of CFRP laminates
  9. Effect of tool material on microstructure and mechanical properties in friction stir welding
  10. Microstructures of an AZ61 wrought magnesium alloy fabricated by a novel SPD process using thermomechanical simulation
  11. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70
  12. Effects of post-curing on the thermo-mechanical behavior and the chemical structure of highly filled phenolic molding compounds
  13. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing
  14. Deep micro-hole drilling of Hardox 500 by electro-discharge machining
  15. Optimization of thin-wall structures using hybrid gravitational search and Nelder-Mead algorithm
  16. Structural design of vehicle components using gravitational search and charged system search algorithms
  17. Electrical resistivity and strength properties of sodium hydroxide contaminated soil solidified with cement
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