Effect of Accumulative Strain on Grain Refinement and Strengthening of ZM6 Magnesium Alloy During Continuous Variable Cross-Section Direct Extrusion

• Published in: Acta metallurgica sinica : English letters 2015-05, Vol.28 (5), p.649-655
• Main Authors: Li, Feng, Shi, Wei, Bian, Nan, Wu, Hong-Bin
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Continuous extrusion; Corrosion and Coatings; Cross-sections; Crystal defects; Deformation; Deformation effects; Dynamic recrystallization; Extrusion; Extrusion dies; Grain refinement; Grain size; Homogenizing; Intermetallic compounds; Magnesium alloys; Magnesium base alloys; Materials Science; Mechanical properties; Metallic Materials; Microstructure; Nanotechnology; Organometallic Chemistry; Plastic deformation; Shear deformation; Spectroscopy/Spectrometry; Strain; Strengthening; Tribology; 动态再结晶; 变截面; 挤压过程; 晶粒细化; 直接挤出; 积累; 连续剪切变形; 镁合金
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-015-0245-5

In order to study the influence of die combination on continuous variable cross-section direct extrusion （CVCDE） in the extrusion process, the accumulative strain formula is derived, and it can be known that the extrusion ratio of various stages directly determines the size of corresponding stage strain by formula. In this paper, as an example of the two interim dies, three die combinations of different angles and extrusion ratio are designed. Aviation magnesium alloy ZM6 is studied, and the results show that dynamic recrystallization is even more complete when continuous shear deformation occurs, so that the refinement and homogenization of microstructure are obtained. By the use of different die combinations, the accumulative strain increases under the conditions of same total extrusion ratio. Thus, the refined crystalline strengthening effect of extrusion deformation can be further analyzed. Due to the dead-zone defects, the actual accumulative strain decreases significantly and the effect of microstructure and performance improvements also decreases with it. Therefore, the optimal design of die combination is the key to the process and product of CVCDE, which provides a scientific basis for the development of severe plastic deformation.