Nondestructive analysis of the deep-drawing behavior of rolled sheets with ultrasonic techniques
The nondestructive characterization of the deep-drawing behavior is essential for the process control and quality assurance of rolled sheets. Complementary to x-ray diffraction techniques, ultrasonic techniques are under development to characterize the deep drawing behavior in terms of the parameters delta r and r m. Measuring the times-of-flight of ultrasonic waves, the fourth-order expansion coefficients of the orientation distribution function are evaluated. Published empirical and theoretical results are used to link the planar anisotropy parameter delta r with the expansion coefficient C13/4 and the mormal anisotropy parameter r m with the coefficient C11/4. In different sets of cold and hot rolled ferritic steel sheets linear correlations are found between the two deep drawing parameters and these expansion coefficients. Based on these correlations an algorithm was developed and applied to evaluate delta r- and r m-values using ultrasonic techniques. The excellent correlation bet ween these data and the delta r- and r m-values given by the manufacturer of the sheets show that ultrasonic techniques hold high promise to characterize the deep-drawing behavior of sheets.