High-power laser and arc welding of thorium-doped iridium alloys

Technical Report · Thu May 01 00:00:00 EDT 1980

DOI:https://doi.org/10.2172/5433133· OSTI ID:5433133

David, S A; Liu, C T

The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent by the fusion zone microstructure and thorium content. The alloy has been welded with a continuous-wave high-power CO/sub 2/ laser system with beam power ranging from 5 to 10 kW and welding speeds of 8 to 25 mm/s. Successful laser welds without hot cracking have been obtained in this particular alloy. This is attributable to the highly concentrated heat source available in the laser beam and the refinement in fusion zone microstructure obtained during laser welding. Efforts to refine the fusion zone structure during gas tungsten-arc welding of Ir-0.3 % W alloy containing 60 wt ppM Th were partially successful. Here transverse arc oscillation during gas tungsten-arc welding refines the fusion zone structure to a certain extent. However, microstructural analysis of this alloy's laser welds indicates further refinement in the fusion zone microstructure than in that from the gas tungsten-arc process using arc oscillations. The fusion zone structure of the laser weld is a strong function of welding speed.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5433133
• Report Number(s): ORNL/TM-7258; TRN: 80-009410
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
30 DIRECT ENERGY CONVERSION
IRIDIUM ALLOYS
WELDABILITY
CRACKS
DOPED MATERIALS
FUELS
GAS TUNGSTEN-ARC WELDING
LASER WELDING
MICROSTRUCTURE
SOLIDIFICATION
THERMOELECTRIC GENERATORS
THORIUM ADDITIONS
TUNGSTEN ADDITIONS
ACTINIDE ALLOYS
ALLOYS
ARC WELDING
CRYSTAL STRUCTURE
DIRECT ENERGY CONVERTERS
FABRICATION
JOINING
MATERIALS
PHASE TRANSFORMATIONS
PLATINUM METAL ALLOYS
THORIUM ALLOYS
TUNGSTEN ALLOYS
WELDING
NESDPS Office of Nuclear Energy Space and Defense Power Systems
360101* - Metals & Alloys- Preparation & Fabrication
360102 - Metals & Alloys- Structure & Phase Studies
300303 - Thermoelectric Generators- Materials
Components
& Auxiliaries