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Microstructure characteristics of GTAW welded joint of a cast Ni 3Al

Pouraliakbar, H ; Sharif University of Technology

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  1. Type of Document: Article
  2. Abstract:
  3. A series of samples with different compositions and parameters were welded together. The alloys were based on Ni-8Al-8Cr-l.5Mo-0.01B %wt composition with Zr additions of 1 and 3 %wt. Crack-free full-penetration welds of castable nickel aluminide alloy were performed using autogenous GTAW technique. It was found that Ni-Ni5Zr eutectic was associated with solidification cracks. Alloys were fully dendritic and also, weld metal consisted of columnar and axial dendrites beside the fusion line and in the middle, respectively. Optical and scanning electron microscopy (SEM) techniques were employed to characterize the composition as well as the weld structure. X-Ray diffraction was utilized to investigate the phase constituents in the weld zone. Also, mechanical properties of the welded seam were evaluated using hardness measurement. Hardness of the base metal was in the range of HV275-315 and the weld hardness was increased to HV350. It is proposed that increase in the hardness inside the weld zone is attributed to carbides formation and precipitation of finely distributed Ni3AI particles. Results presented in this investigation may be used to produce filler wires of optimized composition for conducting crack-free weldments
  4. Keywords:
  5. Base metals ; Conducting crack ; Crack free ; Filler wire ; Full-penetration weld ; Fusion lines ; Hardness measurement ; Microstructure characteristics ; Nickel aluminides ; Phase constituent ; SEM ; Solidification cracks ; Weld metal ; Weld structure ; Weld zone ; Welded joints ; Welded seams ; Weldments ; Zr addition ; Alloys ; Aluminum ; Carbides ; Chromium ; Cracks ; Dendrimers ; Gas welding ; Hardness ; Mechanical properties ; Scanning electron microscopy ; Welded steel structures ; X- ray diffraction analysis ; Zirconium ; Welds
  6. Source: Welding in the World ; Volume 53, Issue SPECIAL ISSUE , 2009 , Pages 595-601 ; 00432288 (ISSN)