METHOD FOR EVALUATING DRAW FORMING PROPERTIES OF ALLOYED ZINC PLATED STEEL PLATE BY X-RAY DIFFRACTION METHOD

PURPOSE:To continuously evaluate draw forming properties in a non-destructive manner without receiving the effect of plating thickness by evaluating draw forming properties on the basis of the evaluation values obtained by measuring the respective intensities of X-ray diffraction of a zeta phase and a background. CONSTITUTION:When a zinc plated steel plate is subjected to alloying treatment, the thickness, that is, the quantity of a zeta phase among the zeta phase, delta-phase and gamma-phase successively grown after a eta-phase disappears from the surface of the plated layer corresponds to the magnitude of the total X-ray diffraction intensity thereof. Based on this, the evaluation value [I(zeta)-IB(zeta)]/I(zeta) calculated from the respective X-ray diffraction intensities I(zeta), IB(zeta) of the zeta phase and a background has good correlation with the quality of a product regardless of a plating adhesion amount. Therefore, draw forming properties can be evaluat ed on the basis of this evaluation value measurable in a manufacturing line.