Construction of a machine-learning-based prediction model for mechanical properties of ultra-fine-grained Fe–C alloy

In recent years, ultra-fine-grained Fe–C alloy have received widespread attention because of their high levels of strength, hardness, and wear resistance. However, these alloy have strict requirements on control of the process parameters during production to meet product specifications. This study was aimed at designing a prediction model for their mechanical properties, which could ultimately promote the industrial development of ultra-fine-grained Fe–C alloy. The effect of process parameters on the mechanical properties of ultra-fine-grained Fe–C alloy was analyzed by electron backscatter diffraction (EBSD) and scanning electron microscope (SEM). By fusing experimental combinations of alloy composition, rolling process, annealing process, and resultant mechanical properties into a dataset for training and verification, a machine-learning-based prediction model of mechanical properties of ultra-fine-grained Fe–C alloy was constructed and tested. When choosing the machine learning algorithm, the best network model was obtained for this application by optimizing a conventional backpropagation (BP) network structure: a three-layer network structure, with a learning rate of 0.5, 18 hidden layer neurons, and activation functions of the hidden and output layers, namely Tansig and Purelin (MATLAB functions), respectively. Finally, the sample data was divided into training set and verification set, and the prediction accuracy, efficiency and generalization ability of BP neural network (BPNN), genetic neural network (GA-BP) and support vector machine (SVM) were compared and analyzed. The superiority of BPNN in the prediction of mechanical properties of ultrafine grained Fe–C alloy was determined, and the mean absolute percentage error (MAPE) of the BPNN for tensile strength, yield strength and uniform elongation are 3.02%, 4.47% and 6.47% respectively, and the number of training steps is 412, which are less than the other two models. The result lays a foundation for the production of high stability and high performance steel products.