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Dissimilar alloy laser beam welding of titanium: Ti-6Al-4V to Beta-C[trademark]. [Ti-3Al-8V-6Cr-4Mo-4Zr]

Journal Article · · Welding Journal (Miami); (United States)
OSTI ID:7244493
;  [1];  [2]
  1. Ohio State Univ., Columbus, OH (United States). Dept. of Welding Engineering
  2. Edison Welding Inst., Columbus, OH (United States)

CO[sub 2] laser beam welds were produced between Ti-6Al-4V and Beta-C[trademark] sheet. Three different nominal fusion zone chemical compositions were obtained by varying the laser beam location relative to the joint centerline and thereby melting different quantities of each base metal. Fusion zone microstructures exhibited fine, columnar-shaped beta grains comprised of retained-beta phase and martensite, with the proportion of martensite increasing with an increase in the quantity of Ti-6Al-4V nominally in the fusion zone. The location of these phases within the fusion zone was influenced by macrosegregation, which originated from incomplete mixing of the melted base metals and the occurrence of transverse-solute banding during solidification. Postweld aging heat treatment at 482 C/20 h and 538 C/8 h resulted in extremely fine alpha precipitation within the retained-beta phase regions and tempering of the martensite. These fusion zone microstructures exhibited high hardnesses and strengths superior to those of the Ti-6Al-4V and Beta-C base metals, but low ductility (<2.5%). An increase in the aging temperature to 593 C promoted fusion zone transformation to a coarser intragranular and grain-boundary alpha + beta microstructure, which exhibited a strength superior to those of the base metals and acceptable ductility. Variations in the proportions of Ti-6Al-4V and Beta C within the weld fusion zone generally had a minimal effect on the average hardness and ductility.

OSTI ID:
7244493
Journal Information:
Welding Journal (Miami); (United States), Journal Name: Welding Journal (Miami); (United States) Vol. 73:7; ISSN 0043-2296; ISSN WEJUA3
Country of Publication:
United States
Language:
English