Development of Aluminum-Base Alloys. Section II

摘要

The development of processes for making high-strength, high quality products from prealloyed atomized Al powders is described. High quality, high-strength 2 in. dia. heat treatable extrusions have been produced by aluminum powder metallurgy methods. Compacts were produced either by cold compacting-hot coining or by hot pressing of preheated powders. The tensile properties of the compacts after heat treating were lower than the heat treated 2 in. dia. extrusions. The properties of duplicate specimens also lacked the uniformity which was present for the extrusions. Cold compacted and sintered material had extremely low tensile properties. It appears possible to produce cold compacted-hot coined billets of 48 in. dia. by 60 in. long on existing presses and with proper tooling. Although the compact properties themselves are not too promising, forging and hot upsetting in a closed die have resulted in the tensile strengths being increased to approximately the level of extruded stock. Sheet produced from forged material also had high properties, greater than 100,000 psi yield strength. The working temperature of these alloys is extremely important. If the high temperature is not maintained, the pieces usually crack. Impacts, produced with both extruded slices and cold compacted-hot coined billets have resulted in burst strengths up to 113,000 psi. Although the weldability of these alloys is better than the Al-Al2O3 alloys, the porosity is still too high for commercial use. (Author)