FORMATION OF THE WELD DEPOSITS AND ITS EFFECT ON THE ALL-WELD-METAL HEAT-AFFECTED-ZONE
The three-dimensional shape of a gas metal-arc weld puddle was graphically constructed using a centerline section of a hammer decanted weld, a weld cross-section and the top surface crater outline of the weld puddle. Velocities of melting and solidification were computed at every point within the weld puddle. The analysis showed that the weld papillary region typically solidified 19 times as fast as the trailing portions of the weld puddle and that the arc jet effect causes papillary penetration. Lateral melting of the weld bead is caused by liquid circulation. Etching with sodium bisulfite solutions revealed patterns of weld solidification segregation. Microprobe study showed that these patterns were evidences of segregation of nickel, manganese, silicon and molybdenum in the last interdendritic liquid to solidify. The forms of solidification structure change from cellular to columnar dendrites with decreasing solidification velocity. The ability to reveal solidification structure as well as normal microstructure yielded evidence that the low alloy weld metals studied solidified as delta ferrite. Columnar austenite grain growth on cooling in the solid state related to dendrite arm spacings. The rentention of fine acicular microstructures of ferrite, bainite and martensite in weld metals subjected to weld reheat cycles was attributed to the retention of original solidification segregation, with the result that the all-weld-metal heat-affected-zone appeared to have a very fine microstructure when viewed by optical microscopy.
- Sponsored by Office of Naval Research.
Lehigh UniversityFritz Engineering Laboratory
Bethlehem, PA United States 18015
- Perle, M M
- Publication Date: 1972-7
- Features: Appendices; Figures; References;
- Pagination: 220 p.
- Issue Number: 58.38
- TRT Terms: Heat affected zone (Metals); Research; Weld tests; Welding
- Old TRIS Terms: Welding research; Welding techniques
- Subject Areas: Marine Transportation; Research;
- Accession Number: 00035676
- Record Type: Publication
- Source Agency: Ship Structure Committee
- Report/Paper Numbers: NR 064-509
- Contract Numbers: N00014-68-A-0514
- Files: TRIS
- Created Date: Oct 13 1972 12:00AM