Non-Contact Nondestructive Evaluation of Stud Welding - Key Technology Fixing Parts on Base in Light Metals -

摘要

Light metals have been spreading in many engineering fields. Aluminum alloy and magnesium alloy are becoming popular as a material of body of electro equipments; cellular phones and personal computers. Stud is used for fixing parts on the body. Because boss forming is fiuther difficult when the thickness of body is thin. However the welding of aluminirai and magnesium is not simple because of its high thermal conductivity and easy oxidizability. Therefore an effective method for nondestructive test of welding is desired to perform a 100-percent inspection. We propose a new nondestructive inspection method for stud welding, in which a stud is exited electromagnetically and the vibration of stud head is measured with a laser Doppler velocimeter. We applied this method to two groups of magnesium alloy stud welding specimen, one welded with the optimum energy, the other welded with insufficient energy. The welding area of these specimens was measured with X-Ray Computed Tomography. We introduced a new parameter K, which is the average amplitude in the low fi'equency range of the amplitude spectrum of displacement at the stud head. The two groups could be distinguished vsith the accuracy of 90% by using the parameter K.