STUDY OF MICROPLASTIC PROPERTIES AND DIMENSIONAL STABILITY OF MATERIALS
Abstract
Microyield stresses of 39-40 ksi for Ni-Span-C, 69-70 ksi for 440 C stainless steel, and 7.5 ksi for A 356 cast aluminum have been determined. Microyield stress tests are in progress for Ti-5Al-2.5Sn, beryllium, and aluminum oxide. Experiments have shown that residual strains of 20-40 micro in./ in. increase the microyield stress, but a small fraction of this increase is lost upon allowing the specimen to recover at room temperature for up to 24 hours. Electron microscope studies indicated that microplastic flow in Ni-Span-C is the result of dislocation generation at second phase particles in grain boundaries. For A 356 cast aluminum, the generation of interfacial dislocations at Mg2Si particles appeared to be the controlling mechanism. Experiments are being conducted to determine, and eventually minimize, the residual stresses introduced by machining in all of the materials being studied. In addition, the effects on dimensional stability of load and thermal cycling, and plastic strain are being investigated. A prototype capacitor strain gage has been constructed. The design is currently being modified to eliminate slippage of the page elements as the specimen is loaded and unloaded. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1967
- Accession Number
- AD0831716
Entities
People
- Albert G. Ingram
- Frank C. Holden
- Robert E. Maringer
Organizations
- Battelle Memorial Institute