Forging Temperature Effects on Crack Tip Creep Behaviour of Hot Hammer Forged Ti-6Al-4V Alloy

Abstract

The creep behaviour of hot hammer forged Ti-6Al-4V alloy under different forging temperatures has an essential influence on their high-temperature service performance. In this article, the high-temperature mechanical property and creep behaviour of Ti-6Al-4V alloy forging at different forging temperatures were first investigated experimentally. Then, in view of the critical effect of microcracks and other defects on the service life of components in forging, the creep characteristics at the tip of a 2 mm crack were characterized by the finite element method. The results show that when the Ti-6Al-4V alloy was forged at 1000°C, the high-temperature mechanical property was improved, and the steady-state creep rate and creep residual deformation were significantly reduced. In addition, the creep strain and creep rate at the crack tip were decreased apparently during creep, and the creep strain gradient in the crack tip region was also significantly reduced. This indicates that the creep deformation of Ti-6Al-4V alloy can be controlled by an appropriate forging temperature during hot hammer forging process and might delay the crack propagation to improve the service life of components.

The Effect of the Forging Process on the Microstructure and Mechanical Properties of a New Low-Cost Ti-5Al-1.5Mo-1.8Fe Alloy

“…Ref. [ 17 ] states that the service life and reliability of Ti-6Al-4V alloy components can be effectively improved by designing suitable forging process parameters, including optimizing the forging temperatures while minimizing the scrap and energy consumption generated during the forging production process. Titanium components are forged below the β phase transition temperature to achieve the desired microstructure [ 18 ].…”

“…In Ti-Mo-Fe alloys, combining different plastic deformation mechanisms has been found to enhance the strength–ductility trade-off [ 19 ]. A high deformation rate during forging results in finer grains, and the primary strengthening mechanism employed during forging is grain refinement strengthening [ 17 , 20 ]. Lou et al investigated the impact of different forging parameters on the phase transformation of a Ti-6Al-4V alloy during hot hammer forging [ 21 ].…”

“…Lou et al investigated the impact of different forging parameters on the phase transformation of a Ti-6Al-4V alloy during hot hammer forging [ 21 ]. Therefore, controlling the forging temperature is crucial when performing hot hammer forging plastic-forming processes, as it significantly influences the resulting forging properties [ 17 ]. Y. Chong et al revealed that a bimodal microstructure with an equiaxed primary α had an excellent balance between its strength and ductility [ 22 , 23 ].…”