Weld-Metal Grain Structure and Mechanical Properties of Iridium Alloy DOP-26
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Weld metal grain structure and mechanical properties of the Ir-0.3% W alloy (DOP-26) doped with 60 ppm Th and 50 ppm Al have been investigated by use of a gas tungsten arc (GTA) welding process. The fusion zone grain structure is strongly influenced by heat input and puddle shape and therefore by the bead width. With increasing bead width from 2.5 to 3.7 mm, the grains in the fusion zone show a sharp change in growth direction near the centerline region and develop a fine columnar structure with grains growing parallel to the welding direction. Mechanical properties of the welds and base metal were characterized by tensile and impact tests from 650 to 1150°C. The ductility and fracture behavior of DOP-26 welds are sensitive to weld bead width, postweld heat treatment, and weld-test orientation. The ductility of the welded specimens increases with increasing test temperature and decreasing weld bead width. The transverse weld specimen with a wide-bead width (3.7 mm) has the lowest impact ductility, and the longitudinal weld with a narrow-bead width (2.5 mm) has the highest elongation at all the test temperatures. The impact ductility of the transverse weld specimen with the narrow-bead width falls between the limits. All the results are discussed in terms of the fusion zone grain structure and fracture path of the welds.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5150151
- Report Number(s):
- ORNL--5857; ON: DE82019899
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CRYSTAL STRUCTURE
IRIDIUM ALLOYS
IRIDIUM BASE ALLOYS
JOINTS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NESDPS Office of Nuclear Energy Space and Defense Power Systems
PLATINUM METAL ALLOYS
TUNGSTEN ALLOYS
WELDABILITY
WELDED JOINTS