Report No. 1: Effect of carbon migration in Cr-Mo weldments on metallurgical structure and mechanical properties
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
The occurrence and behavior of a carbon denuded ``soft`` zone in Cr-Mo weldments was studied to determine its influence on mechanical properties and in-service behavior. Room temperature tensile tests, creep rupture tests and Moire interferometry evaluations were performed in order to characterize the behavior of this unique zone in Cr-Mo weldments. The zone is brought about by chromium level differentials between the weld metal and base metal. Extensive metallography was accomplished using OLM, SEM and STEM techniques. The results show that the occurrence of the carbon denuded ``soft`` zone is due to carbon migration, which is driven by elemental differences (especially in chromium) between the weld metal and base metal. The extent of carbon migration depends on the PWHT schedule. Higher strain accumulation and work hardening and/or a constraint effect has been observed in the ``soft`` zone during room temperature testing. However, the work hardening/constraint effect is minimal at elevated temperatures (in the creep regime), hence the ``soft`` zone is a potential failure location in elevated temperature service.
- OSTI ID:
- 248121
- Journal Information:
- Bulletin - Welding Research Council, Journal Name: Bulletin - Welding Research Council Journal Issue: 407; ISSN 0043-2326; ISSN WRCBA2
- Country of Publication:
- United States
- Language:
- English
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