Abstract
This paper encompasses the development of a microstructure-based numerical model (FEM) of the conveyor cooling process after the hot forging of industrial steel with accurate predictions of the volume fraction of phases as yield and tensile strengths. An experimental procedure for validating the FEM was conducted using optical and scanning electron microscopy and tensile tests. Results showed very good agreement between the phase predictions of the 3D FEM model and those obtained from direct measurement of forged parts, with an average error of about 3.6 and 6.9 % for ferrite and pearlite phases, respectively. Tensile test results were evaluated at a 90 % reliability level, and very good agreements were obtained with an error of about 3 and 5 % for the yield and tensile strengths. The methodology could predict the phase transformations, and the mechanical properties during cooling after the hot forging of the steel were investigated.

Key words
Finite Element Method (FEM), reliability, microstructure, tensile stress, hot forging, controlled cooling, P355NL1 steel

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