Accession Number:

AD0607225

Title:

MECHANISM OF FATIGUE DEFORMATION AT ELEVATED TEMPERATURES.

Descriptive Note:

Technical rept.

Corporate Author:

COLUMBIA UNIV NEW YORK INST FOR THE STUDY OF FATIGUE AND RELIABILITY

Personal Author(s):

• RONAY,M.
• Reimann,W. H.
• Wood,W. A.

Report Date:

1964-06-01

Pagination or Media Count:

13.0

Abstract:

The basic mechanism of fatigue is studied in annealed alpha-brass subjected to alternating torsion at room temperature, 100C, 200C, 300C, and 400C and in air. It is shown that the slip-zone microcracking which characterizes fatigue damage produced by small amplitudes at room temperature is progressively replaced by grain-boundary cracking at elevated temperatures, replacement being complete at 400C. Replacement occurs not because slip activity decreases but because slip-movements at elevated temperatures cease to concentrate in narrow zones and instead disperse. Decrease of amplitude at 400C though permitting longer lives of specimens before fracture actually causes increase in grain-boundary damage, an anomaly attributed to the greater difficulty at elevated temperature of starting and propagating a crack. Surface corrosion was most pronounced along slip-bands but since at elevated temperatures the slip bands showed no cracking, the surface corrosion did not appear to influence onset and early spread of fatigue damage. Author

Descriptors:

• *FATIGUE(MECHANICS)
• *HIGH TEMPERATURE
• HIGH TEMPERATURE
• SCIENTIFIC RESEARCH
• FATIGUE(MECHANICS)
• BRASS
• DEFORMATION
• GRAIN BOUNDARIES
• CRYSTAL DEFECTS
• FRACTURE(MECHANICS)
• SURFACE PROPERTIES
• CORROSION
• MICROSTRUCTURE

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE