DEVELOPMENT OF DEEP DRAWN - ONE PIECE HIGH PERFORMANCE ROCKET MOTOR CASE
LYON INC DETROIT MICH
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Progress is reported on the fabrication of special tooling. The hot cup, first draw, second draw, third draw, and fourth draw die assemblies are complete. The fifth draw, sixth draw, and heading dies are nearing completion. Three cases were processed through three cold drawing operations each of which was followed by anneal at 1250 F for 1 hr. A chamber AT-1 was sectioned for metallurgical analysis after completion of the hot cup operation and subsequent heat treatment. The total range in hardness over the entire section was from 98 to 99 Rockwell B. The grain flow pattern was radial in the dome and parallel to the longitudinal axis in the sidewall of the cup. The structure possessed a relatively fine ferritic grain ASTM 7 to 8 and was completely spheroidized. Partial decarburization after normalizing treatment was indicated by an average carbon content of 0.34 in the outer 0.005 in. of material as compared to 0.43 carbon in the 0.005- to 0.010-in. layer. The microstructure and grain flow in all sections are in the optimum condition for subsequent cold work.