Constitutive modelling of the high strain rate behaviour of interstitial-free steel

Abstract A physically based modelling and experimental investigation of the work hardening behaviour of IF steel covering a wide range of strain rates including complex strain path and/or strain rate changes are presented. In order to obtain isothermal stress–strain curves at high strain rates, a procedure has been proposed with the aid of finite element analysis. The result reveals that the apparent excess of the flow stress after a jump in strain rate, which is frequently observed in bcc metals, is in fact due to the thermal softening at large strains, and that the flow stress after a jump in strain rate tends asymptotically to the values corresponding to the curve at the new strain rate. The strain rate affects not only the short-range stress but also the long-range stress via the strain-rate dependant evolution of dislocation structures. The proposed model is based on the dislocation model of intragranular hardening proposed by Teodosiu and Hu [Teodosiu, C., Hu, Z., 1995. Evolution of the intragranular microstructure at moderate and large strains: modelling and computational significance. In: Shen, S., Dawson, P. R., (Eds.), Proceedings of Numiform'95 on Simulation of Materials Processing: Theory, Methods and Applications. Balkema, Rotterdam, pp. 173–182] and extended to strain rate sensitive one with applying the results of the thermal activation analysis. A satisfactory agreement has been achieved between model predictions and experimental results.

[1]  J. D. Campbell,et al.  The temperature and strain-rate dependence of the shear strength of mild steel , 1970 .

[2]  T. Tanaka,et al.  The temperature dependence of the yield stress and solid solution softening in FeNi and FeSi alloys , 1971 .

[3]  J. R. Klepaczko,et al.  Shear testing of a sheet steel at wide range of strain rates and a constitutive relation with strain-rate and temperature dependence of the flow stress , 2001 .

[4]  W. Spitzig,et al.  Solid-solution softening and thermally activated flow in alloys of Fe with 3at.% Co, Ni or Si , 1971 .

[5]  J. Duffy,et al.  Strain rate history effects and observations of dislocation substructure in aluminum single crystals following dynamic deformation , 1983 .

[6]  B. Bacroix,et al.  Microstructure and texture evolution under strain-path changes in low-carbon interstitial-free steel , 2001 .

[7]  Albert Van Bael,et al.  Modelling of plastic anisotropy based on texture and dislocation structure , 1997 .

[8]  Amos Gilat,et al.  Modeling torsional split Hopkinson bar tests at strain rates above 10,000 s ¿1 , 2002 .

[9]  F. Smidt.  An analysis of thermally activated flow in α iron based on T−τ∗ considerations , 1969 .

[10]  B. Clausen.  Characterisation of polycrystal deformation by numerical modelling and neutron diffraction measurements , 1997 .

[11]  Albert Van Bael,et al.  Prediction of forming limit strains under strain-path changes: Application of an anisotropic model based on texture and dislocation structure , 1998 .

[12]  N. Takeda,et al.  On High-Velocity Brittleness and Ductility of Dual-Phase Steel and Some Hybrid Fiber Reinforced Plastics , 1985 .

[13]  M. Ashby,et al.  THE MOTION OF A DISLOCATION, ACTED ON BY A VISCOUS DRAG, THROUGH AN ARRAY OF DISCRETE OBSTACLES. , 1971 .

[14]  G. B. Gibbs.  Thermodynamic analysis of dislocation glide controlled by dispersed local obstacles , 1969 .

[15]  A. Seeger,et al.  CXXXII. The generation of lattice defects by moving dislocations, and its application to the temperature dependence of the flow-stress of F.C.C. crystals , 1955 .

[16]  Albert Van Bael,et al.  Finite element modeling of plastic anisotropy induced by texture and strain-path change , 2003 .

[17]  J. Harding.  The effect of grain size and strain rate on the lower yield stress of pure iron at 288°K , 1969 .

[18]  Akhtar S. Khan,et al.  Behaviors of three BCC metal over a wide range of strain rates and temperatures: experiments and modeling , 1999 .