TY - GEN
T1 - Dislocation-source hardening in nanostructured steel produced by severe plastic deformation
AU - Kamikawa, Naoya
AU - Huang, Xiaoxu
AU - Hansen, Niels
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2010
Y1 - 2010
N2 - Annealing-induced hardening and deformation-induced softening behavior has recently been found in nanostructured aluminum (fcc) produced by severe plastic deformation. It has also been demonstrated that annealing led to a decrease in ductility while deformation led to an increase in ductility. These mechanical responses are totally opposite to those in conventional coarse-grained samples. The present study explores the effect of post-process annealing or deformation on mechanical properties of nanostructured interstitial free (IF) steel (bcc). Accumulative roll-bonding was used to produce the nanostructured IF steel. The deformation structure was characterized by a lamellar boundary structure with a mean spacing of about 200 nm, consisting of high-angle boundaries, low-angle dislocation boundaries and dislocations in the volume between the boundaries. When the deformed sample was annealed at 400°C for 0.5 h, the yield stress and ultimate tensile strength increased and the elongation to failure decreased markedly. In contrast, when the annealed treatment was followed by a light rolling deformation of 15 % thickness reduction, the strength decreased and the elongation to failure increased. These results are consistent with those observed in the aluminum samples. Structural observations by transmission electron microscopy indicated that a removal of dislocations between the boundaries leads to a lack of dislocation sources, resulting in a higher stress to activate alternative dislocation sources. It was suggested that deformation rather than annealing could be a new route to improve the ductility of nanostructured metals and that a moderate light deformation gives a good balance of strength and ductility.
AB - Annealing-induced hardening and deformation-induced softening behavior has recently been found in nanostructured aluminum (fcc) produced by severe plastic deformation. It has also been demonstrated that annealing led to a decrease in ductility while deformation led to an increase in ductility. These mechanical responses are totally opposite to those in conventional coarse-grained samples. The present study explores the effect of post-process annealing or deformation on mechanical properties of nanostructured interstitial free (IF) steel (bcc). Accumulative roll-bonding was used to produce the nanostructured IF steel. The deformation structure was characterized by a lamellar boundary structure with a mean spacing of about 200 nm, consisting of high-angle boundaries, low-angle dislocation boundaries and dislocations in the volume between the boundaries. When the deformed sample was annealed at 400°C for 0.5 h, the yield stress and ultimate tensile strength increased and the elongation to failure decreased markedly. In contrast, when the annealed treatment was followed by a light rolling deformation of 15 % thickness reduction, the strength decreased and the elongation to failure increased. These results are consistent with those observed in the aluminum samples. Structural observations by transmission electron microscopy indicated that a removal of dislocations between the boundaries leads to a lack of dislocation sources, resulting in a higher stress to activate alternative dislocation sources. It was suggested that deformation rather than annealing could be a new route to improve the ductility of nanostructured metals and that a moderate light deformation gives a good balance of strength and ductility.
KW - Dislocation-source hardening
KW - Interstitial free (IF) steel
KW - Nanostructured metals
KW - Severe plastic deformation
KW - Strengthening mechanism
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U2 - 10.4028/www.scientific.net/MSF.638-642.1959
DO - 10.4028/www.scientific.net/MSF.638-642.1959
M3 - Conference contribution
AN - SCOPUS:75849161353
SN - 0878492941
SN - 9780878492947
T3 - Materials Science Forum
SP - 1959
EP - 1964
BT - THERMEC 2009
A2 - Chandra, Tara
A2 - Chandra, Tara
A2 - Chandra, Tara
A2 - Wanderka, N.
A2 - Wanderka, N.
A2 - Wanderka, N.
A2 - Reimers, Walter
A2 - Reimers, Walter
A2 - Reimers, Walter
A2 - Ionescu, M.
A2 - Ionescu, M.
A2 - Ionescu, M.
PB - Trans Tech Publications Ltd
T2 - 6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009
Y2 - 25 August 2009 through 29 August 2009
ER -