The heat-affected-zone (HAZ) liquation cracking susceptibility of wrought Waspaloy subjected to simulated, multiple postweld heat treatment (PWHT) cycles was evaluated using hot ductility testing. The hehavior of both a wrought bar material and a forged turbine disk with different chemical compositions was evaluated. A long-term isothermal heat treatment was used to simulate multiple PWHT cycles that Waspaloy turbine engine components would experience during periodic weld repair of aircraft components. The results reveal that the weldability of Waspaloy after a 1079 C deg/40-h heat treatment degrades which is primarily due to increased grain size from longterm, elevated-temperature exposure. The finer grain size of the wrought bar accounted for its minimal degradation of weldability, while coarse grains resulted in a drastic deterioration of weldability in the forged disk. Local Ti-rich, MC-type carbide constitutional liquation and segregation-induced grain boundary liquation leads to a degradation of weldability in the simulated HAZ of Waspaloy materials. A 1079 C deg/100-h treatment resulted in a restoration of the weldability of the forged disk even with comparable coarse grain size to that of simulated 1079 C deg/40-h treated material. This improvement resulted from the high fraction of special grain boundaries resulting from this heat treatment. Grain size and special grain boundary are the two primary factors influencing HAZ liquation cracking after multiple PWHTs. The presence of abundant special grain boundaries dominated the effect of grain size in the heat-affected zone of the Waspaloy bar stock and the forged disk.
The effect of multiple postweld heat treatment cycles on the weldability of waspaloy
Welding Journal, New York ; 81 , 11 ; 233S-238S
2002
6 Seiten, 7 Bilder, 5 Tabellen, 15 Quellen
Article (Journal)
English
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