Yermolenko D. Modification of the dendritic structure of the metal of welded joints of high-strength low-alloyed steels by dispersed inoculants

The thesis is aimed on studying of the inoculation of refractory non-metallic inclusions (inoculants) to the weld pool effect on the kinetics of dendritic structure formation of high-strength-low-alloyed (HSLA) steels welds. Investigations were carried out on the developed mathematical model and software, which is able to simulate the process of weld pool solidification with influence of dispersed refractory inoculants HSLA steels welds. Results showed that the inoculants may control parameters of the dendritic structure, final weld metal microstructure and mechanical properties of weld metal. It was used few different compounds (TiC, TiN, SiC, TiO2, Al2O3, ZrO2, MgO) with different surface activity. Numerical calculations and experimental studies have shown that a decrease in the contact angle between molten weld metal and inoculants increases size of columnar dendrite.