REDUCTION OF GEAR WEIGHT BY INERTIA WELDING TITANIUM WEBS TO STEEL GEAR RINGS

BECAUSE OF ITS WEIGHT REDUCTION POTENTIAL, IT WOULD BE ADVANTAGES TO USE BIMETALLIC STEEL RING/TITANIUM WEB GEARS IN POWER TRANSMISSION ASSEMBLIES. ALTHOUGH SEVERAL TECHNOLOGIES EXIST FOR JOINING TITANIUM TO STEEL, FACTORS SUCH AS COST, SIZE-FLEXIBILITY, RELIABILITY, POSTFABRICATION PROCESSING, JOINT EFFICIENCY, AND EXTREME TEMPERATURE OPERATION RAPIDLY REDUCE THE NUMBER OF REALISTIC JOINING PROCESSES. PRIOR RESEARCH AND ACTUAL MANUFACTURING EXPERIENCE SHOW INERTIAL WELDING (ONE KIND OF FRICTION WELDING) IS THE BEST PROCESS FOR PRODUCING BIMETALLIC GEARS TO MEET THE ABOVE CRITERIA. HOWEVER, THERE IS A TECHNOLOGICAL LIMIT IN THE SIZE OF TITANIUM-STEEL INERTIAL WELDED JOINTS BEYOND WHICH BRITTLE INTERMETALLIC PHASES DETERIORATE JOINT MECHANICAL PROPERTIES. PHASE I RESEARCH WOULD INCLUDE INERTIA WELDING GEAR BLANKS CONTAINING AN ALUMINUM ALLOY INTERFACE TO OVERCOME WELD JOINT BRITTLENESS SO THAT CONVENTIONALLY-SIZED GEARS CAN BE PRODUCED. TITANIUM-TO-STEEL WELD JOINTS WOULD BE MADE WITH AND WITHOUT ALUMINUM, TORSION TESTED, AND MICROSTRUCTURALLY EXAMINED TO DETERMINE THE QUALITY OF THE INERTIA WELDED GEAR BLANKS. IT IS ANTICIPATED THAT SMOOTH, HARDENED STEEL RINGS CAN BE SUCCESSFULLY BONDED BY INERTIAL WELDING TO A TITANIUM WEB AND USED WITH LITTLE SUBSEQUENT PROCESSING. PHASE II WOULD INVESTIGATE LARGE DIAMETERS AND WIDTHS, OTHER (POSSIBLY BETTER) INTERFACE MATERIALS, AND CONTOURED JOINT SUFACES.