Accession Number : AD0755844

Title :   The Effect of Surface Layer on Plastic Deformation and Crack Propagation.

Descriptive Note : Semiannual rept. Jul-Dec 72,

Corporate Author : MARTIN MARIETTA CORP DENVER COLO DENVER DIV

Personal Author(s) : Kramer,Irving R.

Report Date : DEC 1972

Pagination or Media Count : 29

Abstract : S AND NUMBER OF FATIGUE CYCLES WAS ESTABLISHED FOR 4130 STEEL (yield strength = 180,000 psi). Confirming the results found for aluminum (2014-T6) and titanium (6Al-4V), fatigue failure occurred when the surface layer stress attained a critical value. The crack propagation rate was measured for 4130 steel at yield strengths of 180,000 and 100,000 psi. The results showed that the SLE treatment improved the crack resistance. Pressure vessels of 4130 steel have been obtained and processed for fatigue testing. Welded specimens of 4130 steel have been made by butt-welding plates and machining out appropriate strips. The microstructure and hardness profile were determined and the specimens readied for test. A four-point fatigue apparatus and associated mechanism for detecting fatigue failure was designed and constructed. (Author)

Descriptors :   (*STEEL, CRACK PROPAGATION), CREEP, SURFACE PROPERTIES, PRESSURE VESSELS, FATIGUE(MECHANICS), MICROSTRUCTURE, HARDNESS, STRAIN(MECHANICS), STRESSES

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE