A micromechanical flow curve model for dual phase steels


  • Sawitree Sodjit Faculty of Engineering, King Mongkut’s University Technology Thonburi
  • Vitoon Uthaisangsuk Faculty of Engineering, King Mongkut’s University Technology Thonburi


Dual phase steel, Flow curve, Microstructure, Representative volume element, Phase boundary dislocation


In the automotive industries, Dual Phase (DP) steels have become a favoured material for the car body parts due to their excellent combination of high strength and good formability. A microstructure of DP steel generally consists of a matrix of ferrite reinforced by small islands of martensite. Experimental investigations showed that effects of martensite phase fraction, morphology, and phase distribution play an important role for the mechanical and fracture behaviours of the dual phase steel. In the present work, an approach concerning FE based modelling for predicting flow curve of DP steels has been introduced using a Representative Volume Element (RVE). Two dimensional RVE models were prepared on microstructural level using micrographs of the investigated DP steels having different martensite phase fractions. The applied physical flow curve models of the individual single phases are based on dislocation theory and take into account the local chemical compositions. The models also include phase boundary dislocation (PBD) density, which accumulates at the phase boundaries due to the austenite-martensite transformation during quenching process. These dislocations contribute to both an increase in forest dislocations and a building up of back stresses. The calculated stress-strain curves for the DP steels were verified with experimental results determined from tensile tests. Furthermore, the micromechanics based model was used to describe the local stress and strain development of the individual phases in the DP microstructures. By this manner, an optimization of the dual phase high strength steel with respect to its microstructural constituents is possible.


Download data is not yet available.


Final Report USLAB (1998). Ultra light steel auto body. American Iron and Steel Institute, Washington, DC.

Rashid, M.S. (1981). Dual phase steels. Ann. Rev. Mater. Sci. (11) : 245-266.

World Auto Steel (2009). Advanced high strength steel (AHSS) application guidelines, URL: http://www.worldautosteel. org access on 15/03/2009.

Park, K.S., Park, K.T., Lee, D.L., Lee, C.S. (2007). Effect of heat treatment path on the cold formability of drawn dual-phase steels. Mater. Sci. Eng. A (449-451): 1135–1138.

Ramazani, A., Mukheriee, K., Prahl, U., Bleck, W. (2012). Modelling the effect of microstructural banding on the flow curve behavior of dual-phase (DP) steels. Comp. Mater. Sci. 52(1): 46-54.

Albbasi, F. (2004). Micromechanical modeling of dual phase steels. PhD Thesis, McGill University, Montral, Canada.

Rodriguez, R.M., Gutierrez, I. (2003). Unified formulation to predict the tensile curves of steels with different microstructures. Mater. Sci. Forum (426-432): 4525-4530.

Bouaziz, O., Buessler, P. (2002). Mechanical behavior of multiphase materials: An intermediate mixture law without fitting parameter. La Revue de Metallurgie (99): 71-77.

Uthaisangsuk, V., Prahl, U., Bleck, W. (2008). Micromechanical modelling of damage behaviour of multiphase steels. Comp. Mater. Sci. (43): 27-35.

Delince, M., Brechet, Y., Embury, J.D., Geers, M.G.D., Jacques, P.J., Pardoen, T. (2007). Structure– property optimization of ultrafinegrained dual-phase steels using a microstructure based strain hardeningmodel. Acta Materialia (55): 2337–2350.

Sinclair, C.W., Poole, W.J., Brchet, Y. (2006). A model for the grain size dependent work hardening of copper. Scripta Materialia. (55):739-742.




How to Cite

S. Sodjit and V. Uthaisangsuk, “A micromechanical flow curve model for dual phase steels”, J Met Mater Miner, vol. 22, no. 1, Jun. 2012.



Original Research Articles