Dynamic Recrystallization: The Dynamic Deformation Regime
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DYNAMIC recrystallization (DRX) has been observed in a variety of extreme deformation or severe plastic deformation (PD) systems for several decades, especially in association with adiabatic shear bands (ASBs). Grebe et al.[1] and Meyers and Park[2] were among the first to recognize DRX grains (~300 nm in diameter) in ASBs in impact plugging in W targets, while a preliminary investigation in Cu indicated the possibility for DRX during high-strain, high-strain-rate deformation.[3] The DRX in shock-conditioned Cu was observed by Andrade et al.[4] while Meyers et al.[5] made similar observations in Ta. Chokshi and Meyers[3] proposed that DRX was responsible for the super-PD characteristic of high-strain-rate systems such as shaped charge jet formation, while Murr et al.[6,7] confirmed this proposal through direct observations of DRX in both Cu and Ta recovered shaped charge jet and slug fragments. Shaped charge jet formation and jetting and flow during impact crater formation in Cu were compared, and DRX was described as providing a mechanism for extreme plastic flow in jetting.[8] The DRX was described as composed of ASBs and ASBrelated flow zones for a tungsten heavy alloy (WHA) penetration into thick Cu targets by Kennedy and L.E. MURR, Murchison Professor, is with the Department of Metallurgical and Materials Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA. C. PIZAN˜A, formerly Research Assistant in the Department of Metallurgical and Materials Engineering, The University of Texas at El Paso, El Paso, TX 79968, is a Senior Materials Science Engineer with Lockheed Martin Space SystemsMichoud, New Orleans, LA 70129, USA. Contact e-mail: lemurr@ utep.edu This article is based on a presentation made in the symposium entitled ‘‘Dynamic Behavior of Materials,’’ which occurred during the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals, Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee. Article published online June 13, 2007 METALLURGICAL AND MATERIALS TRANSACTIONS A
Murr,[9] who also simulated the DRX zone along the penetration channel. Trillo et al.[10] more recently demonstrated that the W-4 pct Ta, [001] single-crystal penetrator fragments that comprised the penetrator erosion tube in a rolled homogeneous armor (RHA) target exhibited DRX associated with or composed of ASBs and related solid-state flow features. Pizan˜a et al.[11] also recently illustrated the dominant role of DRX in the solid-state flow of both [001] single-crystal W penetrator rods and the penetrated RHA target material. The DRX has been recognized to be the dominant microstructural feature of friction-stir welding (FSW), which exemplifies extreme deformation involving high strains and high strain rates.[12–15] Murr et al.[16] have argued in this context that the accommodation of severe PD in impact crater formation, ballistic rod flow and penetration in thick targets, shaped charge formation,
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