Simulation of the welding of irradiated materials
Helium was uniformly implanted using the tritium trick technique to levels of 0.18, 2.5, 27, 105 and 256 atomic part per million (appm) for type 316 stainless steel, and 0.3 and 1 appm for Sandvik HT-9 (12 Cr-1MoVW). Both full penetration as well as partial penetration welds were then produced on control and helium-containing materials using the autogenous gas tungsten arc (GTA) welding process under full constraint conditions. For full penetration welds, both materials were successfully welded when they contained less than 0.3 appm helium. However welds of both materials, when containing greater than 1 appm helium, were found to develop cracks during cooling of the weld. In type 316 stainless steel, catastrophic intergranular failure occurred during cooling in the heat-affected zone (HAZ), leading to a crack extending nearly the length of the plate at the completion of the weld. When the helium content of type 316 stainless steel exceeded 100 appm both HAZ cracking and brittle failure along the center line of the fusion zone occurred during cooling. In HT-9 the observed cracking was limited to only the beginning region of the weld. The cracking was found to be intergranular in nature and occurred along prior-austenite grain boundaries of the HAZ. For partial penetration welds, underbead intergranular cracking occurred in the HAZ of type 316 stainless steel containing helium greater than 2.5 appm. Transmission and scanning electron microscopy indicated that the HAZ cracking was caused by the growth and coalescence of grain boundary (GB) helium bubbles. This cracking occurred as a result of the combination of high temperatures and high shrinkage tensile stresses. The cracking in the fusion zone was found to result from the precipitation of helium along dendrite interfaces. A model based on the kinetics of diffusive cavity growth is presented to explain the observed results.
- Research Organization:
- Auburn Univ., AL (USA)
- OSTI ID:
- 7123191
- Country of Publication:
- United States
- Language:
- English
Similar Records
Welding of helium-doped austenitic and ferritic stainless steels
Simulation of the welding of irradiated materials
Related Subjects
360101 -- Metals & Alloys-- Preparation & Fabrication
360106* -- Metals & Alloys-- Radiation Effects
ALLOYS
ARC WELDING
AUSTENITIC STEELS
BRITTLENESS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CHROMIUM-NICKEL-MOLYBDENUM STEELS
CORROSION RESISTANT ALLOYS
CRACKING
DECOMPOSITION
EMBRITTLEMENT
FABRICATION
GAS TUNGSTEN-ARC WELDING
HEAT AFFECTED ZONE
HEAT RESIS
HELIUM EMBRITTLEMENT
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
JOINING
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
POST-IRRADIATION EXAMINATION
PYROLYSIS
STAINLESS STEEL-316
STAINLESS STEELS
STEEL-CR17NI12MO3
STEELS
THERMOCHEMICAL PROCESSES
WELDING
ZONES