回転電極法粉末を熱間静水圧プレスして製造したTi-6Al-6V-2Sn合金の組織と機械的特性

Abstract

The effect of post-consolidation heat treatment on the microstructure and the resultant mechanical properties were evaluated both at room and cryogenic temperatures (77 K and 4 K) for hot isostatically pressed (HIP) Ti-6Al-6V-2Sn alloy powders made by the rotating electrode process (REP).The uniform, high integrity properties equivalent to wrought mill annealed material were obtained by this fabrication method.The post-consolidation heat treatment had a marked effect on the microstructural modification. The highest ductility was obtained for as-HIP fabricated and mill annealed materials. The solution treated and aged (STA) material showed the highest strength with moderate ductility, whereas the beta annealed materials exhibited the lowest strength and ductility. The fracture toughness showed the highest value in the as-HIP fabricated condition, and the lowest in the STA condition. The good properties combinations obtained in the as-HIP fabricated condition could be attributable to the formation of finer and lower aspect ratio alpha platelets during alpha-beta HIP treatment.The comparison with HIP consolidated REP Ti-6Al-4V alloy powders showed that strength was somewhat higher for Ti-6Al-6V-2Sn, whereas ductility was higher for Ti-6Al-4V, especially at cryogenic temperatures.