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A powder metallurgy (P/M) forging technology for production of critical Army automotive gears was established. The variables investigated during the program included powder compositions, forging temperature, die temperature, preform configuration, press type and a combined wrought-P/M process (composite) for producing forged gears. The selected process employed 4600 prealloyed powder and sintering and forging temperatures of 2200F. A simplified preform configuration involving 3 dimensional metal flow in a closed die system was used to produce forged pinions. An extrude-forge process was employed to produce the gears. The properties of the P/M forged material were shown to be comparable to wrought material of similar composition. Cost analysis indicated that the process was capable of providing significant cost reductions achieved through material savings and reduction or elimination of machining operations.

The program was aimed at developing a process to produce complex shaped high performance components at reduced costs. The component, the cover for the M85 model .50 caliber machine gun, was creep forged to near net shape to eliminate many finish machining operations. The process employed minimum deformation type dies operating in the temperature range of 1300 to 1450F and using the superplastic behavior of fine grained, as-received and pretreated 46XX prealloyed powders. Process variables of die temperature, forging pressure and time as well as preform treatments, including loose powder, were investigated. Die temperature was found to be the major variable. Forgeability was found to be related to grain size, however, near theoretical density forgings were produced using as-received commercial powder and forging parameters of 1550-1600F die temperature and 20 KSI pressure. (Modified author abstract)

Borsic(SiC coated B fibers)/Ti-6Al-4V composites have been successfully fabricated using the full reinforcement potential of the filaments. Multiple filament breaks were found to occur prior to longitudinal composite failure and hence improvements in the filament strength distribution would suggest improvement in tensile strength. Transverse failure was found to be limited by failure of the interface, filament splitting and inadequate interlaminar bonding. Improved control of the filament spacing would therefore give rise to improved transverse strengths. The temperature dependence of the longitudinal strength is similar to that of the filaments showing a reduction in in situ filament strength. The transverse tensile strength is nearly independent of temperature indicating a limiting mechanism also relatively independent of temperature. This is shown to be predominately interface failure with some fiber splitting. The properties and simplicity of the system have been shown to make Borsic/Ti-6Al-4V a potentially superior composite material with a wide range of applications. (Modified author abstract)