The properties of steels depend in a complex way on their composition and heat treatment and neural networks have therefore recently been widely used for capturing these relationships. Two different methods of reducing the network connectivity, viz a pruning algorithm and a multi-objective predator prey genetic algorithm, have been used for neural network modeling of the mechanical properties of high strength steels, so that relevant connections within the networks are revealed. This provides important understanding on the variables and their relationship with mechanical properties. In the pruning algorithm the lower layer of the network is gradually reduced by removing less significant connections. In the predator prey algorithm, a genetic algorithm based multi-objective optimization technique is used to train the neural network and a Pareto front is developed by minimizing the training error along with the network size. The results of both techniques reveal that they can extract more knowledge from the data, which is difficult to obtain from conventional neural models. The relative relevance of the composition and processing parameters detected could be used for designing steel with tailored property balance. The results developed by the two techniques are also found to be comparable.KEY WORDS: high strength multiphase steel; neural network model; pruning algorithm; genetic algorithm; multi-objective optimization; predator prey algorithm; alloy design. ISIJ International, Vol. 47 (2007), No. 8, pp. 1195No. 8, pp. -1203No. 8, pp. 1195 © 2007 ISIJ of metallurgy, but the quantitative relations are not always known. Artificial neural networks (ANN) are learning systems, which try to learn and map the existing input output relationship in an accurate way on the basis of experimental information, and have been found successful in developing prediction model for the properties of TMCP steels. 2,3) ANN methods have also been found superior compared to traditional regression techniques in case of prediction of properties of steel. 4,5) An ANN analysis usually depends on published data or data developed in the laboratories, and that often implies working with a diminutive databank. Sometimes, due to the large number of potential inputs the practical limitation may lead to over-fitting of the ANN model where the abilities of extracting meaningful information from the data are lost. An established method for avoiding over-fitting is to restrict the number of connectivity (weights) between the inputs and the hidden nodes and even to restrict the numbers of inputs and hidden nodes. 6,7) In addition to avoiding over-fitting, with its detrimental effect on model accuracy, a detection of the relevant connections within the network could provide important understanding on the variables and their relationship.In the present work two different methods of reducing the network connectivity have been used for modeling the mechanical properties of high strength steels. Firstly an intuitive pruning algorithm 8) with a large sigmo...