| A Study of the Hot Workability of Al-8.5 Wt Pct Mg Alloys for Armor Plate Applications |
JAN 89 |
67 pages |
| Authors:
Joseph R. Pickens; Frenk H. Heubaum; MARTIN MARIETTA LABS BALTIMORE MD
|
 | Hot-torsion tests were conducted to examine the hot workability of standard and enhanced purity A1-8.5 wt% Mg ingots in both the as-cast and homogenized conditions. The enhanced purity variant showed substantially higher hot ductilities at all homogenization and deformation temperatures investigated with no change in equivalent tensile flow stress. The optimum homogenization practice consists of two stages, namely stage-1 for >5 h at 427 C (800 f) plus >6 h ... |
|
| The Delayed Fracture of Aluminum Alloys |
OCT 85 |
|
| Authors:
Joseph R. Pickens; Timothy J. Langan; MARTIN MARIETTA LABS BALTIMORE MD
|
 | The relationship between susceptibility to stress-corrosion cracking (SCC) and grain boundary (GB) chemistry was investigated in an attempt to elucidate the SCC mechanism in aluminum-zinc-magnesium alloys. Research was performed in two phases: (1) develop a method for inducing intergranular fracture on the actual grain boundary to enable measurement of GB composite by Auger electron spectroscopy (AES) and (2) attempt to relate changes in GB composition to changes in SCC susceptibility. ... |
|
| The Delayed Fracture of Aluminum Alloys, End of Year Report |
MAY 1983 |
|
| Authors:
Joseph R. Pickens; Timothy J. Langan; Guy D. Davis; Leontios Christodoulou; Leslie Struble; MARTIN MARIETTA LABS BALTIMORE MD
|
| Research was performed in two areas: The role of grain boundary (GB) segregation in the stress-corrosion cracking (SCC) of Al-Zn-Mg alloys, and mechanism of SCC in Al-Li binary alloys. In the segregation area, a technique of measuring GB segregation was developed that uses liquid gallium to expose the GB's for examination by static and scanning Auger electron spectroscopy. GB segregation of Mg attoms, not bound in MgZn precipitates, was found. ... |
|
| The Delayed Fracture of Aluminum Alloys, End of Year Report |
MAR 1982 |
|
| Authors:
Joseph R. Pickens; David Venables; Guy D. Davis; Jonathan R. Gordon; MARTIN MARIETTA LABS BALTIMORE MD
|
| The mechanisms of failure of high-strength aluminum alloys in saline environments was investigated. It was found that the mechanism of stress corrosion cracking (SCC) in a commercial Al-Mg alloy, 5083, is dominated by hydrogen embrittlement (HE). The dominant contribution of HE was discerned by comparing SCC susceptibility under Modes I and III loading. The influence of the surface oxide film on the SCC susceptibility of 7075 and 7175 alloys was ... |
|
| The Delayed Fracture of Aluminum Alloys. |
JAN 1981 |
|
| Authors:
Joseph R. Pickens; David Venables; John A. S. Green; MARTIN MARIETTA LABS BALTIMORE MD
|
| The fundamental mechanism of stress-corrosion cracking (SCC) has been studied for high-purity Al-Zn-Mg alloys. Earlier work at our laboratory and elsewhere established that hydrogen embrittlement is involved in the SCC mechanism. Moreover, we previously proposed that a Mg-H interaction exists that facilitates hydrogen entry into the alloy and its concentration at the grain boundary, leading to embrittlement. In the present work, we demonstrated the adverse effect of Mg in the ... |
|
| The Delayed Fracture of Aluminum Alloys. |
MAY 1980 |
|
| Authors:
Joseph R. Pickens; Dave Venables; John A. S. Green; MARTIN MARIETTA LABS BALTIMORE MD
|
| The stress corrosion cracking (SCC) of high purity Al-Zn-Mg alloys has been studied in terms of the effects on SCC susceptibility of: bulk chemistry, bulk microstructure, oxide film chemistry, and oxide film morphology. For alloys having equivalent solute content (wt. % Zn + wt. % Mg), higher bulk concentrations of magnesium lead to slightly increased susceptibility in acetic-acid-brine solution. Interrupted quenching failed to produce a microstructure exhibiting reduced SCC susceptibility. ... |
|
Reports by Author
