A study of the interactive effects of strain, strain rate and temperature in severe plastic.pdf

Available online at /locate/actamat Acta Materialia 57 (2009) 5491–5500A study of the interactive effects of strain, strain rate and temperature in severe plastic deformation of copper Travis L. Brown a, Christopher Saldana a, Tejas G. Murthy a, James B. Mann a, Yang Guo a, Larry F. Allard b, Alexander H. King c, W. Dale Compton a, Kevin P. Trumble d, Srinivasan Chandrasekar a,* aCenter for Materials Processing and Tribology, School of Industrial Engineering, Purdue University, West Lafayette, IN 47907, USA bOak Ridge National Laboratory, Oak Ridge, TN 37831, USA cAmes Laboratory, Ames, IA 50011, USA dCenter for Materials Processing and Tribology, School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA Received 18 May 2009; received in revised form 23 July 2009; accepted 23 July 2009 Available online 26 August 2009Abstract The deformation field in machining was controlled to access a range of deformation parameters—strains of 1–15, strain rates of 10– 100,000 s1 and temperatures of up to 0.4 Tm—in the severe plastic deformation (SPD) of copper. This range is far wider than has been accessed to date in conventional SPD methods, enabling a study of the interactive effects of the parameters on microstructure and strength properties. Nano-twinning was demonstrated at strain rates as small as 1000 s1 at 196 C and at strain rates of P10,000 s1 even when the deformation temperature was well above room temperature. Bi-modal grain structures were produced in a single stage of deformation through in situ partial dynamic recrystallization. The SPD conditions for engineering specific microstruc- tures by deformation rate control are presented in the form of maps, both in deformation parameter space and in terms of the Zener– Hollomon parameter.  2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Severe plastic deformation; High speed deformation; Dynamic recrystallization; Copper; Ultrafine grained microstructure1