A comparative study on Johnson-Cook and modified Johnson-Cook constitutive material model to predict the dynamic behavior laser additive manufacturing FeCr alloy

An accurate prediction of flow behavior of metals considering the combined effects of strain, strain rate and temperature is essential for understanding flow response of metals, and a key requirement for numerical modeling and simulation of machining. Thus, the effects of high strain rate and elevated temperature on the deformation behaviors of FeCr alloy specimen, obtained by laser additive manufacturing ( LAM), were investigated by Split Hopkinson Pressure Bar tests with the strain rates of 1000-8000 s(-1) and temperature range of 20-800 degrees C. Strain rate softening effect was found at high strain rate and discussed. Based on the experimental results, the Johnson-Cook model and modified Johnson-Cook model were established for the LAM FeCr alloy. The predictions of these constitutive models were compared using statistical measures like correlation coefficient and absolute average error. Analysis of statistical measures reveals that J-C model has more deviation from the experimental values. Whereas, the predictions of modified J-C model are very close to the experimental results, which is better model for predicting the dynamic behavior of the LAM FeCr alloy. (C) 2017 Elsevier B.V. All rights reserved.