TESTING METHOD FOR JOINING STRENGTH OF CLAD MATERIAL

PURPOSE:To easily measure the joining strength at each part of a clad material in a nondestructive way by deciding the shear or peeling strength of the clad material based on the ratio of echoes from the bottom face of a standard test piece to echoes from the bottom face of the clad material obtained from ultrasonic tests. CONSTITUTION:Echoes F1 from the bottom face of a standard test piece which is composed of a single plate 10 made of a clad material 12 or base material and has nearly the same thickness as the clad material has are adjusted to constant. Any clad material may generate a small amount of intermediate echoes Fc at a joint surface even when the material has no defect. By measuring the pitch F'1 of echoes from the bottom face of the clad plate to be measured, the ratio (F'1/F1X100) of echoes from the bottom face of the clad plate to echoes from the bottom face of the standard test piece is calculated. In case the joining strength of joint surfaces is weak due to partial delamination, the echoes F'1 becomes weaker and, in this example, the echo becomes 70%. The then shear strength and peeling strength are found from the measured echo ratio by using a predetermined relation between the shear strength or peeling strength and echo ratio.