Repair welding of carbon steel that has been partially graphitized during service

Plain carbon steels that are in service at elevated temperatures (typically 400-450 °C) for prolonged periods of time (typically in excess of 20 years) may experience graphitization, often in the heat affected zone (HAZ). This study aimed to determine the effects of HAZ graphite on the mechanical pr...

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Bibliographic Details
Published in:Welding in the world 2017-06, Vol.61 (4), p.703-710
Main Authors: Kruger, KJ, Pistorius, PGH, Orsmond, CPM
Format: Article
Language:English
Subjects:
Carbon
Carbon steels
Chemistry and Materials Science
Gas tungsten arc welding
Graphite
Graphitization
Heat affected zone
Heat treating
High temperature
Materials Science
Mechanical properties
Metallic Materials
Repair welding
Research Paper
Shielded metal arc welding
Solid Mechanics
Tensile properties
Theoretical and Applied Mechanics
Welded joints
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Summary:Plain carbon steels that are in service at elevated temperatures (typically 400-450 °C) for prolonged periods of time (typically in excess of 20 years) may experience graphitization, often in the heat affected zone (HAZ). This study aimed to determine the effects of HAZ graphite on the mechanical properties of plain carbon steels as well as to characterize the graphite that was observed. Additionally, it was required to evaluate whether repair welding of graphitized material was viable. A combination of gas-tungsten arc welding and shielded metal arc welding was used, in association with various joint configurations. A number of extended heat treatments were performed. Transverse tensile samples did not always fracture through the HAZ graphite. Failure in the graphitized HAZ resulted in a decrease in reduction in area; no other tensile properties were affected by the presence of HAZ graphite. A prediction of the location of the HAZ graphite was developed using the Rosenthal equation. It was demonstrated that it is possible to perform repair welding on graphitized material using conventional welding procedures.
ISSN:0043-2288
1878-6669
DOI:10.1007/s40194-017-0456-7