Chemical reactions role in pores formation during welding of titanium alloys

An attempt is made, on a base of thermodynamic computations, to qualitatively evaluate the probability of occurrence in a welding bath of various chemical reactions during the welding of titanium alloys in inert gases. The results are presented of the thermodynamic computations of the chemical reactions probability when the welding bath is affected by moisture, carbon dioxde, hard carbon or silica. It is found, that chemical reactions exhibit a considerable effect on the process of the voids formation in the welded joints of titanium alloys. The surface contamination and moisture, being the main 'suppliers' of the chemical reactions products in the welding bath, intensify the voids formation due to the increase in a latent pressure of gases (H2, CO, SiO) in the welding bath and due to the hard particles - 'activizers' of the gas bubbles nucleation