Thermal aging effects on the microstructure of Nb-bearing nickel based superalloy weld overlays using ultrasound techniques

摘要: Abstract Secondary phases such as Laves and carbides are formed during the final stages of solidification nickel based superalloy Inconel 625 coatings deposited gas tungsten arc welding (GTAW) cold wire process. However, when aged at high temperatures, other can precipitate in microstructure, like γ″ δ phases. The aim this work was to evaluate different thermal aging as-welded material through ultrasound inspection, well influence background echo backscattered signals on computational classification microstructures involved. experimental conditions employed an temperature 650 °C for 10, 100 200 h. were acquired using transducers with frequencies 4 5 MHz then processed determine velocity attenuation, study produced by wave propagation. Both signal types used effectiveness speed classifying secondary phases, detrended fluctuation analysis Hurst method pre-processing Karhunen–Loeve Transform microstructures. processing tools considered sufficiently sensitive, fast accurate detection alloy nondestructive technique.