High quality of rolled steel, demands a stable production technology and constant monitoring of the product by reliable methods. Monitoring of mechanical properties of rolled steel by destructive methods is time and cost consuming and cannot guarantee the quality over the whole length of the coil. Therefore the use of these tests results for characterization of process and product stability is restricted. Accordingly, it is necessary to develop nondestructive methods characterized by high speed and accuracy, so as to guarantee satisfactory mechanical properties of the sheet. Material tensile strength and yield strength are main technical characteristics of cold rolled low-carbon steel. In this thesis, at first the relation between microstructural and mechanical properties of low-carbon steel, were studied. Then the correlation of microstructural and magnetic properties, were investigated and at last a relation between mechanical and magnetic properties was established. So the interdependence between the mechanical and magnetic parameters of material permits the utilization of nondestructive evaluation techniques by electromagnetic procedures. Among the existing numerous nondestructive testing techniques micromagnetic methods such as hysteresis (B-H) loop and non linear harmonic analysis (which reflects all magnetic parameters of hysteresis loop) are known to be very effective for the iection of ferritic steel mechanical properties. Therefore a system was designed and constructed for measuring of these parameters. Measurements and test results showed that odd harmonics of exciting current and voltage of pick up coil can be used for estimating mechanical properties of low- carbon steel. So, these parameters were selected as inputs of designed neural network to estimate mechanical properties. The designed neural network was trained, validated and tested with 500 different samples of Mobarakeh Steel Company's sheets and proved the system can estimate mechanical properties with acceptable accuracy. Key words: 1-Measuring mechanical properties, 2-Magnetic properties, 3-Microstructural properties of ferritic steel sheet
