Viscoplastic Damage Constitutive Modelling of High-Speed Railway Axle Steel 25CrMo4

Abstract:

Ductile damage inadvertently exists in the steel during hot tension. The ductile damage during hot forming directly influences the mechanical properties of 25CrMo4 steel for high-speed railway axle. To investigate the grain growth/refinement rule and damage features of 25CrMo4 in hot forming, grain growth test and grain refinement test were conducted using the thermal mechanical simulator Gleeble-1500. In the grain growth test, the specimens were compressed to ensure that the initial austenitic grain size was small enough, then held at the deformation temperatures (1223K, 1273K, 1323K and 1373K) for 0min, 10min, 20min and 30min, respectively, to study the grain growth rule. In the grain refinement test, the specimens were stretched to different strain level at three temperatures (1313K, 1373K and 1433K) with two strain rates of 1.0/s and 10.0/s to study the grain refinement rule. The micro-voids and micro-cavities were found in tensile specimens during grain refinement test. Based on damage evolution mechanisms, damage constitutive equations are formulated to model the evolution of micro-voids and micro-cavities for 25CrMo4 under hot forming conditions. Partial experiment data were used to determine the material constants in damage constitutive equations by using the Genetic Algorithm (GA) method. To validate the model, the experimental data and computed curves of effective stress and grain size were compared. Close agreements were found between the experimental and prediction results. The developed viscoplastic damage equations are able to characterize the deformation behaviour of 25CrMo4 in hot tension process.

• Periodical: Key Engineering Materials (Volumes 622-623)
• Pages: 679-686
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.622-623.679
• Online since: September 2014
• Authors: Yuan Ming Huo, Bao Yu Wang*, Qian Bai, Jian Guo Lin
• Keywords: 25CrMo4, Constitutive Modelling, High-Speed Railway Axle Steel, Hot Tension, Internal State Variables Method, Viscoplastic Damage

References

[1] G. Xu, L.N. Wang, S.Q. Li, L. Wang, Hot deformation behavior of EA4T steel, Acta Metallurgica Sinica(English Letters). 25 (2012) 374-382.

[2] J. Li, Numerical simulation research on the hollow high-speed railway axle during radical forging, Taiyuan university of science and technology, (2007).

[3] C.M. Li, X.D. Shu, Z.H. Hu, Feasibility study on multi-wedge cross wedge rolling of railway axles with finite element analysis, Zhongguo Jixie Gongcheng/China Mechanical Engineering, 17(2006) 2017-(2019).

[4] J. Lin, A.D. Foster, Y. Liu, D.C. Farrugia, T.A. Dean, On micro-damage in hot metal working. P. 2 Constitutive modeling, Engineering Transactions, 55(2007) 43-60.

[5] L.M. Kachanov, The theory of creep (teoriya polzuchesti), National Lending Library for Science & Technology, (1967).

[6] Y. N. Robotnov, Creep problems in structural mechanics, (1969).

[7] J. Lemaitre, J.L. Chaboche, Mechanics of solid materials, Cambridge university press, (1994).

[8] D.R. Hayhurst, P.R. Dimmer, C.J. Morrison, Development of continuum damage in the creep rupture of notched bars, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 311 (1984) 103-129.

DOI: 10.1098/rsta.1984.0021

[9] D.R. Hayhurst, F.A. Leckie, C.J. Morrison. Creep rupture of notched bars, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 360 (1978) 243-264.

DOI: 10.1098/rspa.1978.0066

[10] J. Lin, Y. Liu, T.A. Dean, A review on damage mechanisms, models and calibration methods under various deformation conditions, International Journal of damage mechanics, 14 (2005) 299-319.

DOI: 10.1177/1056789505050357

[11] Y. Liu, J. Lin, T.A. Dean, D.J. Farrugia, A numerical and experimental study of cavitation in a hot tensile axisymmetric testpiece, The Journal of Strain Analysis for Engineering Design, 40(2005) 571-586.

DOI: 10.1243/030932405x30768

[12] Y. Liu. Characterisation of microstructure and damage evolution in hot deformation, Manufacturing and Mechanical Engineering, University of Birmingham, (2004).

[13] W.H. Zhang, Y.Q. Cai, Advanced Topics In Science and Technology In China: Continuum Damage Mechanics and Numerical Applications, Springer, (2010).

[14] Ø. Grong, H.R. Shercliff, Microstructural modelling in metals processing, Progress in materials science, 47 (2002) 163-282.

DOI: 10.1016/s0079-6425(00)00004-9

[15] M.F. Horstemeyer, D.J. Bammann, Historical review of internal state variable theory for inelasticity, International Journal of Plasticity, 26 (2010) 1310-1334.

DOI: 10.1016/j.ijplas.2010.06.005

[16] M. Toloui, S. Serajzadeh, Microstructural evolution on streamlines during hot strip rolling using internal state variables, Journal of Materials Processing Technology, 209 (2009) 1717-1728.

DOI: 10.1016/j.jmatprotec.2008.04.019

[17] H. Li, Damage and repair evolution of cold formed linepipe steel, University of Birmingham, (2010).

[18] J. Cao, J. Lin, A study on formulation of objective functions for determining material models, International Journal of Mechanical Sciences, 50(2008) 193-204.

DOI: 10.1016/j.ijmecsci.2007.07.003