Constitutive Relations between Stress, Strain-Rate and Temperature of Mild Steel

Strain-rate and temperature dependence on the flow stress of mild steel is discussed. To investigate the influence of grain size and carbon content, low carbon steel S 15 C and S 35 C annealed at different temperatures were prepared. Tensile tests were made ranging in strain-rate from 2.78 × 10Zs-1 to 1.39 × 10-1 s-1 and temperature from -33°C to 700°C with an Instron-type testing machine. Experimental results were compared with a theory proposed previously by the first author for constitutive relationship of elastic/viscoplastic materials. The proposed equation represented well experimental results of constitutive relations except the blue brittleness region. Elongation, reduction in area and superplasticity of materials were discussed in connection with deformation mechanism regions.