열처리된 알루미늄 합금의 초음파 비선형 특성 평가

초록

In this study, ultrasonic nonlinear characteristics in the heat-treated aluminum alloy have been evaluated. The nonlinearity of ultrasonic wave has been measured as the acoustic nonlinear parameter , depending upon the amplitude ratio of the second-order harmonic and the fundamental frequency component of ultrasonic wave propagating through the materials. The parameter measurement has been carried out with the reflected signals from the back-wall of specimens at the same plane using the contact-type transducers. The heat-treatment, aging, has been achieved at 300℃ for various durations in the range of 1 to 50 hours. The tensile strength and elongation are obtained by the tensile test and then compared with the parameter . There is a peak of the acoustic nonlinear parameter on 5 hours aging and the decreases thereafter, exhibiting closed relations with tensile strength and elongation. Also, the heat-treatment time showing peak in the parameter was identical to that showing severe change in the σ-ε curve. These results suggest that the acoustic nonlinear parameter can be used for monitoring the strength variations with aging of aluminum alloys.

키워드