Microstructural Stability and Creep Cracking in Ti6242 Alloys

Abstract

A detailed metallographic study of both as-received and creep tested specimens was carried out on Ti-6242 with equiaxed and lamellar microstructures. It was aimed at a better understanding of micro-mechanisms of creep damage, microstructural instability effects on creep crack behavior. Present investigations demonstrated that the dominant micromechanism controlling slow creep crack growth involves the formation of microstructural damage zones ahead of the crack tip leading to the nucleation and growth of a number of cavities/cracks at α grain/subgrain boundaries. The decomposition of metastable β phase and dissolution of interface phase at α/β boundaries during creep loading have less effect on the formation of cavity. The comparison of two microstructures is made to interpret the influence of substructures and dislocation activities on the creep crack behavior of Ti-6242.