RESEARCH AND DEVELOPMENT OF TITANIUM ROCKET MOTOR CASE
PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CT
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On the basis of limited data notched and sustained notched tensile strengths on a full scale 40-in.-diam cylinder, a H content of 240 ppm had no detrimental effect at room temperature on flow-turned material aged to the 180, 000 psi yield strength level. TIG welding by an improved copper-fixturing technique produces more uniform weld bead geometry, substantially less weld porosity but no significant improvement in tensile ductility or fracture toughness as compared with steel fixturing. The failure stress for TIGwelded material was inversely proportional to the numerical incidence of porosity, regardless of the weld technique. Limited data indicated that electron beam welds are less susceptible than TIG welds to crack initiation and growth at weld porosity. Closed-die press forging of subscale 14-in.-diam and full scale 40- in.-diam domes at 1850 F with the reductions employed and using the present die configuration produced low tensile ductility after aging to the 180,000 psi yield strength level.