THE EVOLUTION OF ULTRA-HIGH STRENGTH STEELS, AND RESEARCH ON MATERIALS AND VARIOUS NOVEL TECHNIQUES OF FABRICATION OF HIGH PERFORMANCE ROCKET MOTOR CASES
MELLON INST PITTSBURGH PA
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Efforts are being made to produce filaments finer than 0.006 in. in diameter from Al alloys 2024, 5056, and 7075. Uniaxial mechanical strength properties of MX-55 and MX-56 were investigated as a function of tempering temperature. Impact tests indicated little, if any, distinction between the melting process andor the total gas content in candidate missile steel, MX-2. Uniaxial edge notch tests on Rocoloy 270 indicate that at a stress concentration factor of 17, sheet product from air melting and vacuum consumable arc melting processes appear to be similar in all respects. Weldability studies on various Rocoloy 270 analyses, showed that weldability is considerably improved in the presence of W as a partial substituent for Mo. Preparations for weld grain refinement using ultrasonic vibration were continued. Hydrostatic tests of scale model 3.5-in.-diam chambers heat-treated to several strength levels continued. Hydrospinning appears to improve material characteristics in the circumferential direction.