Residual elastic stress and texture evolution in the surface layer of a Ti-6Al-4 V alloy induced by pulsed radially converging low-energy high-current electron beams

This paper presents the results of investigations into the structure, crystallographic texture and residual stresses of Ti-6Al-4 V alloy samples before and after treatment with a low-energy, high-current electron beam in pulse melting mode and radially convergent geometry. Research shows that this type of electron-beam treatment prevents the formation of a columnar structure in the surface layer that solidifies rapidly. Consequently, its hardness does not increase. It has been established that the residual stresses of the first kind in the α-Ti phase are heterogeneously distributed over the surface of the irradiated sample and are dependent on the crystallographic orientation of the surface α-grains. The α-grains forming the basic texture are the most elastically stressed, and the α-grains forming the prismatic texture are the least elastically stressed. The residual stress level of α-grains forming a pyramidal texture occupies an intermediate position between the first two types of grains. A proposed explanation for these differences is based on crystallographic ideas about the slip systems in the hcp-structure of the α-Ti phase.