TY - JOUR

T1 - Deformation of single crystal hadfield steel by twinning and slip

AU - Karaman, I.

AU - Sehitoglu, H.

AU - Gall, K.

AU - Chumlyakov, Y. I.

AU - Maier, H. J.

N1 - Funding Information: This work was supported by the National Science Foundation contract CMS 94-14525 and CMS 99-00090, Mechanics and Materials Program, Arlington, Virginia and a supplement from the NSF International Program. Professor Chumlyakov's work received support from the Russian Fund for Basic Researches, Grant No. 02-95-00350.

PY - 2000/4/2

Y1 - 2000/4/2

N2 - The stress-strain behavior of Hadfield steel (Fe, 12.34 Mn, 1.03 C, in wt%) single crystals was studied for selected crystallographic orientations ([1̄11], [001] and [1̄23]) under tension and compression. The overall stress-strain response was strongly dependent on the crystallographic orientation and applied stress direction. Transmission electron microscopy and in situ optical microscopy demonstrated that twinning is the dominant deformation mechanism in [1̄11] crystals subjected to tension, and [001] crystals subjected to compression at the onset of inelastic deformation. In the orientations that experience twinning, the activation of multiple twinning systems produces a higher strain-hardening coefficient than observed in typical f.c.c. alloys. Based on these experimental observations, a model is presented that predicts the orientation and stress direction effects on the critical stress for initiating twinning. The model incorporates the role of local pile-up stresses, stacking fault energy, the influence of the applied stress on the separation of partial dislocations, and the increase in the friction stress due to a high solute concentration. On the other hand, multiple slip was determined to be the dominant deformation mechanism in [1̄11] crystals subjected to compression, and [001] crystals deformed under tension. Furthermore, the [1̄23] crystals experience single slip in both tension and compression with planar type dislocations. Using electron back-scattered diffraction patterns, macroscopic shear bands (MSBs) were identified with a misorientation of 9° in the compressed [1̄11] single crystals at strains as low as 1%.

AB - The stress-strain behavior of Hadfield steel (Fe, 12.34 Mn, 1.03 C, in wt%) single crystals was studied for selected crystallographic orientations ([1̄11], [001] and [1̄23]) under tension and compression. The overall stress-strain response was strongly dependent on the crystallographic orientation and applied stress direction. Transmission electron microscopy and in situ optical microscopy demonstrated that twinning is the dominant deformation mechanism in [1̄11] crystals subjected to tension, and [001] crystals subjected to compression at the onset of inelastic deformation. In the orientations that experience twinning, the activation of multiple twinning systems produces a higher strain-hardening coefficient than observed in typical f.c.c. alloys. Based on these experimental observations, a model is presented that predicts the orientation and stress direction effects on the critical stress for initiating twinning. The model incorporates the role of local pile-up stresses, stacking fault energy, the influence of the applied stress on the separation of partial dislocations, and the increase in the friction stress due to a high solute concentration. On the other hand, multiple slip was determined to be the dominant deformation mechanism in [1̄11] crystals subjected to compression, and [001] crystals deformed under tension. Furthermore, the [1̄23] crystals experience single slip in both tension and compression with planar type dislocations. Using electron back-scattered diffraction patterns, macroscopic shear bands (MSBs) were identified with a misorientation of 9° in the compressed [1̄11] single crystals at strains as low as 1%.

UR - http://www.scopus.com/inward/record.url?scp=0033884648&partnerID=8YFLogxK

U2 - 10.1016/S1359-6454(99)00383-3

DO - 10.1016/S1359-6454(99)00383-3

M3 - Article

AN - SCOPUS:0033884648

VL - 48

SP - 1345

EP - 1359

JO - Acta materialia

JF - Acta materialia

SN - 1359-6454

IS - 6

ER -