Predicting the Warm Forming Behavior of WE43 and AA5086 Alloys

Abstract

In the present work, we have studied the formability behaviour of two types of magnesium alloys, WE43 hot rolled and WE43 cold rolled by carrying out uniaxial tensile test at elevated temperatures of 350°C to 500°C both experimentally and numerically at a constant strain rate of 10-3s-1. Finite element (FE) model is simulated in ABAQUS/CAE 6.7-6 using coupled temperature-displacement step at higher temperature considering material's property to be isotropic in nature. The effect of temperature on maximum flow stress and major strain at onset of necking is discussed. The true stress-strain behaviour and necking evolution through strain mapping are predicted from FE model and compared with the experimental results. The results show that with increase in temperature, the maximum flow stress decreases and necking delays with increase in limiting major strain for the Magnesium alloys. The work has been extended to predict the forming limit strains of Al 5086 alloy only on the negative minor strain region using M-K (Marciniak and Kuczynski) concept. An FE model based on M-K concept is simulated at 20°C, 150°C and 200°C using coupled temperature-displacement step considering anisotropic sheet material. A groove is created in the middle of the model with an optimizedf value of 0.99, after much iteration. The forming limit strains from such FE simulations are compared with the available experimental data. The results are encouraging providing scope for further improvements in modelling.