Papers by Keyword: Canned Forging

Abstract: Spray deposition is a novel process which is used to manufacture rapidly solidified bulk and near-net-shape preforms. In this paper, Al-8.6Zn-2.6Mg-2.2Cu alloy was synthesized by the spray atomization and deposition technique. The microstructural development during subsequent hot extrusion, hot rolling and canned forging was investigated by means of scanning electron microscope and X-ray diffraction. The results indicate that the spray-deposited alloy exhibits a uniform microstructure composed of the Al matrix and Mg(ZnCu)2 compounds with various shape. The fragmentation of the Mg(ZnCu)2 phases in the alloy has been regarded as one of the main phenomena during extrusion, rolling and forging. Under T6 temper condition, the hot-extruded Al-Zn-Mg-Cu alloy displays superior strength, and higher than hot-rolled and canned-forged ones.

Abstract: A novel canning technology to forge gamma-TiAl alloys was developed at the BTU Cottbus. A TiAl specimen was encapsulated with multilayer stainless steel foil and glass. The steel foil layers prevented the heat loss through radiation and the glass layer reduced the temperature decrease through conduction. First, the effect of steel foil on the cooling rate was investigated. Cooling curves were recorded for TiAl specimens without steel foil layer, with 1, 2, 3 and 4 layers of steel foil, as well as with 3 coated steel foil layers, respectively. While the unprotected specimen cooled from 1200 °C to 1100 °C within 12 s, the specimen with 3 coated steel foil layers needed 52 s for the same temperature decrease. The efficiency of the glass layer was examined with forging of steel specimens. The cooling rate during forging of the specimen with a glass layer was only half of that without a glass layer. Based on the results, Ti-45Al-0.5Mo-0.5Cu-0.2Si specimens, canned with steel foil and glass, were successfully forged at strain rates of 0.1 s-1 and 0.04 s-1 with warm dies which were heated to 500 °C. Visual and metallographic examinations revealed no cracks, pores or micropores. The microstructures are fine-equiaxed grains.