SOLIDIFICATION AND SEGREGATION IN Cu-Ni AND Cb-Ti WELDMENTS.
ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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A study was made of the influences that base metal chemistry, microstructure, and input weld energies have upon the solidification mode of binary alloy weld metals. For this study weld metals were produced in as-cast Cu-Ni and Cb-Ti alloys, using high and low concentrated energy input welding sources. Metallographic studies of Cu-Ni solidification structures show that a single fusion zone dendrite arm supports epitaxial growth of many weld metal dendrites. Interdendritic melting of cast base metal structure, responsible for the development of fusion zone areas in weldments, is directly related to the melting point of the solvent element and dependent upon the concentrated energy input used for welding fabrication. Microprobe analysis indicates that interdendritic phases of Cu-Ni solidification structures are more highly segregated than dendritic phases, and that fusion zone areas are overall the most critical regions for the development of microsegregation, Metallographic study of Cb-Ti solidification structures shows that an epitaxial relationship exists on a grain and subgrain size level between the fusion zone and weld metal growth structures. Microprobe data show that the level of segregation developed in Cb-Ti weldments is a function of the temperature range between the liquidus and solidus points of the particular alloy and that segregation increases as the width of the temperature range increases. Author
- Properties of Metals and Alloys
- Couplers, Fasteners and Joints