Primary α-Phase VST5553 Alloy with Lamellar Structure Properties Effect

摘要

This investigation was devoted to the effect of different initial structures of primary a-phase on the strength and plastic behavior of forging from VST5553 alloy during uniaxial tensile testing. It was demonstrated that the increase in the amount of prirmiry α-phase led to significant increase of β-phase alloying element concentrations, to increase of the strength in the un-aged condition and also to the increase of the volume fraction of β phase with secondary orpresipitation in case of ageing. Dispersion of secondary a-phase increases with the decreasing ageing temperature and increasing concentrations of alloying elements caused by the increase of the amount of primary a-phase which results in the increase of the strength behavior and deterioration of the plastic behavior. Attempts were made to theoretically describe the obtained dependence of the proof stress on the structure parameters using a theory of dislocations with the uniform strain approximation. The proposed theoretical model is good enough to describe σ0.2 in the initial conditions and it also predicts strength increase for the as-aged condition in comparison with the initial one,however,it doesn't explain growth of σ0.2 with the decreasing ageing temperature.