NONDESTRUCTIVE EVALUATION OF METAL FATIGUE.
Scientific rept. for 1968-69,
SOUTHWEST RESEARCH INST SAN ANTONIO TEX
Pagination or Media Count:
Investigations of nondestructive inspection techniques for the early detection and evaluation of fatigue damage in metals have been extended. Photographs of the fatigue evaluation apparatus are shown, and brief descriptions of the ultrasonic, magnetic perturbation, and electric current injection nondestructive techniques are presented. Results obtained using ultrasonic and electric current instrumentations to monitor a stress-cycled Ti-6Al-4V specimen are presented and discussed. Ultrasonic and magnetic perturbation instrumentations were used to monitor many stress-cycled AISI 4340 steel specimens. Magnetic data were accumulated using a very small Hall effect probe and new signal response characteristics were obtained. Reproductions of many ultrasonic and magnetic records are shown surface photomicrographs showing fatigue microcracks are included. Data are presented that show the lives of AISI 4340 steel specimens can be significantly extended by the local removal of fatigue microcracks. Author
- Metallurgy and Metallography
- Test Facilities, Equipment and Methods