Papers by Keyword: Stress Rupture

Abstract: In this paper, three different double annealing treatments were applied on the 3mm-thick Ti-6Al-2Sn-4Zr-1Mo-2Nb-0.2Si (Ti62421S) alloy plate. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile tests were used to investigate the microstructure and mechanical properties under different temperatures of Ti62421S alloy. The results show that the content of primary α phase (α_p) decreases while transformed β structure (βt) increases with the increasing first-stage annealing temperature. After double annealing treatment, ordered α₂ phase particles precipitate within α_p and the size increases with first annealing temperature. This leads to that with increasing first annealing temperature, ultimate tensile strength (UTS) at 600~650°C increases while elongation decreases. After 1000°C/1h/AC+ 750°C/2h/AC annealing, Ti62421S alloy plate exhibits superior combination of mechanical properties at room and elevated temperatures.

Abstract: A new modified Nb-containing A-286 γ' strengthened austenitic Fe-base superalloy (14Cr- 28Ni-1.5Mo-1W-2Ti-Nb-Al) designated as GH871 in China characterizes with high level of tensile, stress rupture and low cycle fatigue properties at 650°C. However, the stress rupture ductility is low and the crack propagation rates at 650°C creep or creep/fatigue interaction conditions are high. For ductility and crack propagation behavior improvement vacuum melted GH871 can still keep its high strength level, also raise stress rupture ductility and simultaneously to decrease crack propagation rates at 650°C. Our results support GH871 to be used as a disk material in high temperature industry.