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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Acoustic emission during unloading of elastically stressed magnesium alloy

A magnesium alloy was quasi-statically cycled elastically between zero load and tension. Both loading and unloading stress delays were found, and the unloading stress delay was further studied. An analytical expression was written for the unloading stress delay which is an elastic constitutive parameter. The potential use of these results for the acoustic emission monitoring of elastic stress states is discussed.

Lee, S. S.↗
NASA NTRS2017

Magnesium Alloys for Space Hardware Design

There have been advances in magnesium alloy development that NASA has not taken into consideration for space hardware because of a lack of test data. Magnesium alloys offer excellent weight reduction, specific strength, and deep space radiation mitigation. Traditionally, magnesium has been perceived as having too poor of a flammability resistance and corrosion resistance to be used for flight. Recent developments in magnesium alloying has led to the formation of two alloys, WE43 and Elektron 21, which are self-extinguishing and significantly less flammable because of their composition. Likewise, an anodizing process called Tagnite was formulated to deter any concern with galvanic and saltwater corrosion. The Materials Science Branch at Kennedy Space Center is currently researching these new alloys and treatments to better understand how they behave in the harsh environment of space. Successful completion of the proposed testing should result in a more thorough understanding of modern aerospace materials and processes, and possibly the permission to use magnesium alloys in future NASA designs.

microstructure↗
NASA NTRS1956

Tensile properties of AZ11A-0 magnesium-alloy sheet under rapid-heating and constant temperature

Specimens of AZ31A-0 magnesium alloy sheet were heated to rupture at nominal rates of 0.2 F to 100 F per second under constant tensile load conditions. The data are presented and compared with the results of conventional tensile stress-strain tests at elevated temperatures after 1.2-hour exposure. A temperature-rate parameter was used to construct master curves from which stresses and temperatures for yield and rupture can be predicted under rapid-heating conditions. A comparison of the elevated-temperature tensile properties of AZ31A-0 and HK31XA-H24 magnesium-alloy sheet under both constant-temperature and rapid-heating conditions is included.

MATERIALS, PROPERTIES - THERMAL↗
NASA NTRS1973

Nondestructive spot test method for magnesium and magnesium alloys

A method for spot test identification of magnesium and various magnesium alloys commonly used in aerospace applications is described. The spot test identification involves color codes obtained when several drops of 3 M hydrochloric acid are placed on the surface to be tested. After approximately thirty seconds, two drops of this reacted acid is transferred to each of two depressions in a spot plate for additions of other chemicals with subsequent color changes indicating magnesium or its alloy.

Wilson, M. L.↗
NASA NTRS1942

Column strength of magnesium alloy AM-57S

Tests were made to determine the column strength of extruded magnesium alloy AM-57S. Column specimens were tested with round ends and with flat ends. It was found that the compressive properties should be used in computations for column strengths rather than the tensile properties because the compressive yield strength was approximately one-half the tensile yield strength. A formula for the column strength of magnesium alloy AM-57S is given.

Holt, M↗
NASA NTRS1977

Constitutive acoustic-emission elastic-stress behavior of magnesium alloy

Repeated laoding and unloading of a magnesium alloy below the macroscopic yield stress result in continuous acoustic emissions which are generally repeatable for a given specimen and which are reproducible between different specimens having the same load history. An acoustic emission Bauschinger strain model is proposed to describe the unloading emission behavior. For the limited range of stress examined, loading and unloading stress delays of the order of 50 MN/sq m are observed, and they appear to be dependent upon the direction of loading, the stress rate, and the stress history. The stress delay is hypothesized to be the manifestation of an effective friction stress. The existence of acoustic emission elastic stress constitutive relations is concluded, which provides support for a previously proposed concept for the monitoring of elastic stresses by acoustic emission.

Williams, J. H., Jr.↗
NASA NTRS1997

The Corrosion Protection of Magnesium Alloy AZ31B

Corrosion rates for bare and coated Magnesium alloy AZ31B have been measured. Two coatings, Dow-23(Trademark) and Tagnite(Trademark), have been tested by electrochemical methods and their effectiveness determined. Electrochemical methods employed were the scanning reference electrode technique (SRET), the polarization resistance technique (PR) and the electrochemical impedance spectroscopy technique (EIS). In addition, general corrosion and stress corrosion methods were employed to examine the effectiveness of the above coatings in 90 percent humidity. Results from these studies are presented.

Danford, M. D.↗
NASA NTRS1947

Column and Plate Compressive Strengths of Aircraft Structural Martials Extruded 0-1HTA Magnesium Alloy

Column and plate compressive strengths of extruded 0-1HTA magnesium alloy were determined both within and beyond the elastic range from tests of flat end H-section columns and from local instability tests of H-, Z-, and channel section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

Heimerl, George J↗