Modelling of flow stress of dual phase steel under warm tensile deformation

Abstract

In order to evaluate the flow stress of dual phase high strength steel in warm forming processes, the flow stress behaviours of dual phase steel were investigated at different temperatures and strain rates. A mathematical model is proposed to predict the stress–strain curves of dual phase steel during warm tension by employing the hyperbolic sine function of Zener–Hollomon parameter, which can describe the relationship among temperature, strain rate and flow stress under warm tensile deformation correctly. Material constants in the equation are expressed in polynomial form of strain. Parameters in the polynomials were obtained by least square method. The predicted stress–strain curves are in good agreement with experimental results, which confirms that the proposed model is accurate.

Keywords:

• Dual phase steel
• Warm tension
• Flow stress
• Constitutive equation

The research work was supported by the National Science Foundation of China (grant no. 50775102) and the 2006 Qing-lan Project of Jiangsu Provincial Education Department for Academic Leading Person.