POWDERED METAL PREFORMS FOR BARREL LINERS

RECENT IMPROVEMENTS IN HOT ISOSTATIC PRESSING TECHNIQUES HAVE ALLOWED AN AUSTRIAN COMPANY TO SUPPLY FULL LENGTH LINERS MADE FROM NIMONIC 105 TO A SWISS GUN MANUFACTURER. THESE TECHNIQUES HAVE BEEN UTILIZED IN THE U.S. FOR LINING OF TUBES FOR THE CHEMICAL AND NUCLEAR INDUSTRIES AND FOR LINING OF VALVES FOR WEAR AND EROSION RESISTANCE. THIS TECHNOLOGY, BASE UPON COLD AND HOT ISOSTATIC PRESSING TECHNIQUES, WILL BE DEVELOPED FOR THE SPECIFIC MATERIALS OF INTEREST USING STAFF, EQUIPMENT, AND INNOVATIVE TECHNOLOGY TO PRODUCE A SUPERIOR MATERIAL IN THE RIFLED BARREL SECTION WITHOUT AN UNACCEPTABLE COST IMPACT. TWO BASIC APPROACHES COULD BE USED TO ACCOMPLISH THE END OBJECTIVE. THE FIRST APPROACH WOULD BE TO FABRICATE THE LINER AS REQUESTED BY ISOSTATIC PROCESSING, MACHINE THE LINER, SHRINK FIT THE LINER INTO THE CONVENTIONAL BARREL, AND HEAT TREAT. THE SECOND APPROACH WOULD INVOLVE PROCESSING IN A PIGGY-BACK FASHION BARREL-LINER COMPOSITE SPECIMENS IN A COST EFFECTIVE MANNER. THIS APPROACH WOULD BE TO SIMULTANEOUSLY FABRICATE THE LINER AND BOND IT TOP THE BARREL TO AVOID MACHINING TO CLOSE TOLERANCES, INSERTION AND SHRINK FITTING OF THE LINER, AND POSSIBLY THE FINAL HEAT TREATMENT. THIS APPROACH PERMITS LOWER FABRICATION TEMPERATURES, GRAIN SIZE CONTROL AND PERMITS IMPROVED MICROSTRUCTURAL CONTROL. THE COST ANALYSIS WOULD COMPARE BOTH APPROACHES WITH THE CURRENT FABRICATION COSTS AND BENEFITS.