ABSTRACT

In specific environments such as in power stations, welds are exposed to high temperatures and pressure service conditions for extended periods of time. The inhomogeneous distribution of material properties in the HeatAffected Zones (HAZ) effect the mechanical performance ofwelded joints and contribute significantly to determinations of the remnant life of a weld. A good understanding of the changes in mechanical properties across a weld with these changing microstructures is extremely useful for informing remnant life calculations. This article focuses on developing an experimental technique that is able to record the influence of microstructure zones in mechanical and material properties across dissimilar low alloy weldments. A standard tensile specimen geometrywas modified and optimized in order to minimise the temperature variation across theweld zone during testing. A maximum temperature variation of approximately 10°C was achieved at the highest test temperature (535° C). The developed experimental technique was applied to two dissimilar service exposed weldments that were extracted from a coal fired power station. Strain analysis across the weldment showed distinct shifts in strain localization as function of test temperature, and furthermore, the strain localization was different for the two weldments. Although temperature variation along the length of the gauge remains a concern, comparison with homogeneous parent metal test specimens provided reasonable levels of confidence in interpreting the mechanical strength of the steel weldments.