Modelling of High Temperature Multi-Axial Creep Rupture Behaviour of #gamma#-Titanium Aluminide

摘要

The creep behaviour of the intermetallic#gamma#-TiAl under conditions of multi-axial stress isconsidered. The particular alloy tested is known as 4722XD (Ti-47A1-2Mn-2Nb+0.8 percent vol. TiB_2) alloy as produced bythe Howmet Corporation. Tests on plain and round bar doublenotched tensile test pieces with different notch sharpness werecarried out on this alloy at 750 deg C. The creep stressdistributions generated across the notch throats were calculatedby finite element analysis. For each notch geometry a skeletalpoint has been identified where the stress slate is insensitive tothe creep law assumed. Metallographic observations have beenmade of the creep damage developed in the notch throats. It hasbeen found that the location of ibis damage can be correlatedwith the finite clement results using models for the influence ofstate of stress on the creep ductility of materials.