Accession Number : AD0764048

Title :   Acoustic Emission from Aqueous Stress Corrosion Cracking in Various Tempers of 4340 Steel.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Chaskelis,H. H. ; Cullen,W. H. ; Krafft,J. M.

Report Date : JUN 1973

Pagination or Media Count : 22

Abstract : A commercially available system is employed to detect and count acoustic emissions emanating from the aqueous stress corrosion crack propagation in 4340 steel. Standard ASTM E399 compact tension specimens are prepared in four tempering temperatures: 204, 316, 427 and 538C (400, 600, 800, 1000F). Crack length is monitored with a notch opening clip gage. Comparisons show the time rate of emission events to increase with stress intensity in rough correspondence to, but much more rapidly than, the crack velocity. Tempering back tends to suppress the count rate as a warning of fast fracture instability. Some similarity is observed between the areal rate of acoustic emission and factors which influence degree and intensity of plastic flow instability in the fracture process zone. (Author)

Descriptors :   (*STEEL, *STRESS CORROSION), SOUND, NONDESTRUCTIVE TESTING, FRACTURE(MECHANICS), CRACK PROPAGATION

Subject Categories : Properties of Metals and Alloys
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE