Inconel 600 to Carbon Steel Dissimilar Metal Weld
36th Annual CNS-CNA Student Conference - 2012 June 12


Presented at:
36th Annual CNS-CNA Student Conference
2012 June 12
Location:
Saskatoon, Canada
Session Title:
CNS/CNA Student Conference 2012

Authors:
Steven Knapp (University of Ottawa )
Xinjian Duan (CANDU Energy Inc. )
Arnaud Weck (University of Ottawa )
  

Abstract

Inconel 600 pipes welded to Carbon-Steel are used in CANDU nuclear reactors. Fracture of these welded tubes would have important consequences in term of safety, and therefore their mechanical properties need to be better understood. In this study, the weld region was analyzed at various length-scales using optical microscopy, micro hardness testing, small and large scale tensile testing and digital image correlation (DIC). Large grains were observed in the weld region and smaller grains in the Inconel and carbon steel base metals. Micro-hardness profiles showed variations across the weld and through thickness and were justified in terms of residual stresses in the sample. Large tensile samples were extracted from the welded pipe and were used to identify the material in which fracture initiates. In addition, the local strains in each material were obtained using digital image correlation. Local stress-strain curves were built from the DIC data and compared to stress-strain curves obtained from miniature tensile samples extracted from the carbon steel, Inconel and weld regions. The results demonstrate the advantage of using DIC for extracting local material properties in dissimilar weld systems. Variations in the materials stress-strain curves thought thickness are also presented and emphasize the need for obtaining a complete map of the mechanical properties in the weld region for predictive models to be accurate. Preliminary fracture studies will also be presented.

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