The Paton Welding Journal, 2013, №06



2013 №06 (09)

2013 №06 (02)

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The Paton Welding Journal, 2013, #6, 2-10 pages  

Effect of non-metallic inclusions on formation of structure of the weld metal in high-strength low-alloy steels

V.V. Golovko, I.K. Pokhodnya

E.O. Paton Electric Welding Institute, NASU
 
 
Abstract
Investigated was the possibility of using the oxide metallurgy approaches providing for control of the amount, distribution and morphology of the inclusions in metal melts, which affect conditions for formation of microstructure of the weld metal. It was shown that increase in the content of the fine-grained secondary phase can be achieved by varying the content of the fine carbide phase in structure of the weld metal. A high density of distribution of the 0.3—1.0 ?m inclusions containing titanium or zirconium oxides leads to formation of the bainitic structure, whereas the decreased content of carbon in metal and narrowing of the range of bainitic transformations limit the probability of formation of the upper bainite microstructure. It was found that to provide the microstructure characterised by a combination of high values of strength, ductility and toughness it is necessary to form inclusions of a certain composition, size and distribution density in the weld metal. This can be achieved by using the oxide metallurgy methods, which provide for addition of a certain amount of refractory inclusions to the weld pool, limitation of its oxygen content and selection of the deoxidation system, as well as of the required temperature range of intermediate transformations based on the TTT-diagrams and welding thermal cycle. 12 Ref., 9 Tables, 13 Figures.
 
 
Keywords: welding, low-alloy steels, oxide metallurgy, welds, non-metallic inclusions, alloying, microstructure, mechanical properties
 
 
Received:                27.03.13
Published:               28.06.13
 
 
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