RESEARCH AND DEVELOPMENT OF TITANIUM ROCKET MOTOR CASE
PRATT AND WHITNEY AIRCRAFT EAST HARTFORD CONN
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A cathodic hydrogenation technique was developed for H analysis of cold-rolled sheet stock aged to 180,000 psi yield strength. The results indicate that the 200 ppm H level is not detrimental. An O content in the 0.10 to 0.20 range has a pronounced effect on the aging response of press-forged B-120VCA Ti alloy at 900 F. The G sub c test showed greater consistency and better correlation with yield strength than the modified Charpy impact and instrumented-bend tests for determining the fracture toughness of thin sections 0.080 in. of high yield strength 180,000 to 200,000 psi flow-turned material. The results of open-die press forging at various strain rates and temperatures indicated that forging at 1700 F with relatively low strain rates produced the least variation in mechanical properties after aging at 900 F. Closed-die press forging in dogbone dies produced excellent grain flow and grain size. Closed-die hammer-forged pancakes were similar in microstructure to that of open-die press-forged pancakes. Single-pass ring rolling to size at 1800, 1900, or 2000 F was considered satisfactory.