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The investigations of influence of change of sizes of primary dfinishrites in the structure of weld metal on their secondary microstructure and mechanical properties were carried out. It is shown that an increase in the width of dfinishrites is accompanied by a rise in the temperature of start of bainite transformation, but the content of low-temperature bainite in the microstructure of weld grows. The possibility of effect of inoculation by dispersed particles of refractory compounds into welding pool on relationship between the content in the microstructure of weld of components with a coarse-acicular and fine-acicular morphology and, accordingly, on mechanical properties of weld was established. [ABSTRACT FROM AUTHOR]

A study was conducted in order to expand the knowledge base on the mechanisms of the influence of refractory compounds in the weld pool on modification of weld metal structure. Results of experiments on inoculation of TiN, SiC, NbC, VC, TiC, TiO2, Al2O3, MgO, ZrO2 dispersed particles to the liquid metal of the weld pool are given. Possibility of the influence of refractory inoculants as the melt «microcoolants», centers for epitaxial initiation of a new phase in the liquid metal and surface-active compounds on modification of the dendritic structure of the welds was analyzed. It is shown that under the conditions of welding low-alloyed steels by flux-cored wire of «metal core» type in shielding gas atmosphere, the refractory compounds, inoculated to the weld pool, the most actively influence modifying of the primary structure, as surface-active compounds. It is established that the change of dendrite morphology in the weld metal influences the temperature range of the recrystallization process, formation of secondary microstructure and mechanical properties of the welds. 10 Ref., 5 Tables, 8 Figures. [ABSTRACT FROM AUTHOR]