Development of Improved High Strength Alumiunum Powder Metallurgy Products
Abstract
An investigation of high strength aluminum 2024 and 7075 alloys was conducted. Both powder metallurgy (P/M) and conventional ingot metallurgy (I/M) extrusion products were examined with particular attention devoted to fatigue behavior. The P/M alloys were produced from prealloyed, air atomized powders of various average particle diameters (APD) using carefully controlled fabrication procedures. The most significant step was a full vacuum preheat treatment of 80% dense compacts which controlled hydrogen contents of the P/M products, thereby producing equivalent hydrogen contents in both the P/M and I/M alloy products. Laboratory ingots were also produced with chemical compositions and processing parameters identical to those of P/M products. Notch Kt=3 HCF testing (R=0.1) was conducted to maximize the likelihood that HCF differences, if they occurred, would be statistically and metallurgically significant. Fatigue tests were conducted in lab air to simulate service environment, however, testing frequency (100 Hz) would tend to reduce any environmental effect. The products investigated included: (1) undirectional, isothermally vacuum hot-pressed (610 MPa with 10 min dwell at 733 K for 7075 and 753 K for 2024) P/M billets, and (2) extrusions of the I/M and hot-pressed P/M billets (extrusion - preheat 643 K with 10:1 and 25:1 direct extrusion ratios). Extrusion parameters were selected based on the previously reported P/M processing study (1).
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1978
- Accession Number
- ADA073559
Entities
People
- David P. Voss