Effect of friction, backpressure and strain rate sensitivity on material flow during equal channel angular extrusion

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2005-10, Vol.406 (1), p.102-109
• Main Authors: Oruganti, R.K., Subramanian, P.R., Marte, J.S., Gigliotti, Michael F., Amancherla, Sundar
• Format: Article
• Language: English
• Subjects: Backpressure; Cross-disciplinary physics: materials science; rheology; Equal channel angular extrusion; Exact sciences and technology; FEM; Friction; Materials science; Other heat and thermomechanical treatments; Physics; Strain rate sensitivity; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2005.06.031

FEM analysis was used to study the interactions between die friction, backpressure and strain rate sensitivity during equal channel angular pressing. One of the key findings is that strain rate sensitivity causes strain redistribution, resulting in higher equivalent strains and a substantial component of compression in the workpiece. This compression gives rise to effects such as lift-off of the leading end of the workpiece from the die bottom and improved die fill. Friction has different effects at room and elevated temperatures. While a moderate amount is beneficial at room temperature, friction has a detrimental interaction with strain rate sensitivity at high temperature. Backpressure, though largely beneficial, is shown to have negative effects when combined with friction and a high strain rate sensitivity.