A New Phenomenological Model to Predict Forming Limit Curves from Tensile Properties for Hot-Rolled Steel Sheets

A phenomenological model for the prediction of the forming limit curve (FLC) based on basic mechanical properties through a uniaxial tensile test can tremendously shorten the design time of the forming process and reduce the measuring costs. In this paper, a novel phenomenological model named the IMR-Baosteel model (abbreviated as the IB model) is proposed for efficient and accurate FLC prediction of hot-rolled steel sheets featuring distinct variations in thickness and mechanical properties. With a systematic test of the plane strain forming limit (FLC0), it was found that a higher regression correlation exists between the FLC0 and the total elongation under different sheet thicknesses. For accurate assessment of the FLC0 from tensile properties, compared using experiments, the error of FLC0 calculated with the proposed model is within 10%. In the IB model, the left side of FLC can be calculated using a line with a slope of -1 while the right side of the FLC is obtained via a modified Keeler model with the exponent (p) determined as 0.45 for hot-rolled steels. Complete experimental FLCs of hot-rolled steels from measurements and the literature were used to validate the reliability of the proposed model. Resultantly, the prediction of FLCs with the proposed IB model is greatly improved, and agrees much better with the experimental FLCs than the predictions of the well-known Keeler model, Arcelor model and Tata Steel model.