Accession Number : AD0719870

Title :   The Influence of Environment and the Surface Layer on Crack Propagation and Cyclic Behavior.

Descriptive Note : Annual rept.,

Corporate Author : MARTIN MARIETTA CORP DENVER COLO DENVER DIV

Personal Author(s) : Kramer,I. R. ; Kumar,A.

Report Date : FEB 1971

Pagination or Media Count : 59

Abstract : The paper shows that environment has a marked effect on the surface layer stress, and in turn the surface layer has a large influence on crack propagation and cyclic work hardening and softening. The relaxation and formation of the surface layer controls the cyclic creep behavior. In particular, measurements of the surface layer stress during cyclic hardening and softening demonstrated that the change in the applied stress was equal to the change in the surface layer stress. The decrease in the cyclic hardening of specimen deformed in vacuum can be explained on the basis that the surface layer stress is less for specimens deformed in vacuum than for those deformed in air. It was found that media that cause stress corrosion cracking also increase the surface layer stress. An increase in the surface layer stress was found to increase the crack propagation rate. (Author)

Descriptors :   (*CREEP, CONTROLLED ATMOSPHERES), STRESSES, CRACK PROPAGATION, ALUMINUM ALLOYS, TITANIUM ALLOYS, HEAT OF ACTIVATION, VACUUM, STRESS CORROSION, FATIGUE(MECHANICS)

Subject Categories : Properties of Metals and Alloys
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE