Microstructure and properties of hot isostatically pressed A-286

Prealloyed A-286 powder was produced by three techniques; rotating electrode, melt ex-plosion and water atomization. These powders were hot isostatically pressed for 3 h at temperatures of either 1366 or 1477 K and pressures of either 69 or 207 MPa in Armco iron cans. The best tensile properties were obtained for a restricted particle size of the rotating electrode process powder. Properties comparable to wrought A-286 were achieved by outgassing the powder before consolidation and increasing the solutionizing temperature. Fracture in the hot isostatically pressed material appeared to be brittle intergranular in nature but these faceted surfaces contained a fine ductile dimpled struc-ture. The fracture path occurred along prior particle boundaries, which were decorated with fine TiC particles. Each particle gives rise to void initiation and ductile rupture. Preliminary evidence suggests that the hot isostatically pressed material had less scat-ter in mechanical properties than wrought following aging. Formerly with Sandia Labs, Livermore, CA.