Characterization of heterogeneous constitutive relationship of the welded joint based on the stress-hardness relationship using micro-hardness tests

Heterogeneous constitutive properties across the welded zone affect the accuracy of the simulation of the fracture and large plastic deformation of the welded steel joints. Neglecting the heterogeneous nature of the constitutive properties gives rise to the prediction errors in these simulations. To improve the assessment accuracy considering the heterogeneity requires the characterization of the local constitutive properties across the welded zone. This paper proposed a new method to determine the strain hardening exponent from the micro-hardness test according to Considère's necking criterion. The constitutive properties of different regions of the welded steel joint were predicted from the micro-hardness values by the proposed method. The predicted constitutive properties across the welded zone were in good agreement with the experimental results. The effect of the microstructural changes due to the welding on the strain hardening behavior of the welded zone was also discussed.