Ultrasonic velocity measurement for the evaluation of plastic anisotropy of the steel sheet

Plastic anisotropy is one of important factors which determine the drawability of a steel sheet. It has been mainly measured by mechanical tensile test. From the ultrasonic velocities propagating along the relative directions to the rolling direction, CODF (Crystallite Orientation Distribution Function) can be measured and ODC's (Orientation Distribution Coefficients) has some correlations with the plastic anisotropy. In this study the correlations between the plastic anisotropy and ODC's of the cold rolled steel sheet were measured. From the results of ultrasonic velocity measurements the average normal anisotropy, γ and the average planar anisotropy, Δγ could be predicted within the accuracy of ±0.082 and ±0.096, respectively. Acoustic resonance method was applied to measure the ultrasonic velocities and EMAT's were used for generating and detecting the ultrasonic waves