Forming defects control in transitional region during isothermal local loading of Ti-alloy rib-web component.

The forming quality of transitional region plays a key role in the performance of titanium alloy large-scale rib-web component under isothermal local loading forming. In this work, a local eigen model of transitional region in the local loading forming of large-scale rib-web component is extracted so as to catch the detail-forming characteristics of transitional region with low computation time in simulation and experiment cost. Then, based on the local eigen model, the mechanism of forming defects in transitional region and their dependence on processing parameters are studied by the combination of physical experiment and verified finite element (FE) simulation. It is found that the second loading step can be divided into two forming stages according to the material flow pattern: (1) the transverse flow stage and (2) the stable forming stage. In the transverse flow stage, there exists long-range transverse flow of web material and excessive transverse flow would lead to the formation of folding and cavum defects. Moreover, the severities of defects are well correlated with the quantity of material transferred into the first-loading region in this stage. For a certain reduction amount, decreasing spacer block thickness and increasing friction both can decrease the quantity of transferred material and then suppress the development of folding and cavum defects, while the deformation temperature and loading speed have little effect on the quantity of transferred material and defects. In the end, an effective way is put forward to suppress and prevent the defects in transitional region during the local loading forming of titanium alloy large-scale rib-web component. [ABSTRACT FROM AUTHOR]