Material properties and damage mechanisms exhibit significant variation across weldments. Micro tensile (MT) testing of specimens machined from specific narrow weldment zones is one method to characterize local property variation. Although limited, the literature data on micro-tensile specimen testing reports on low-temperature behavior. However, cross-weld local material data at high service temperatures have not been reported yet. In the present study, MT tests are conducted across similar P22 and P91 steel welds at 550°C and 600°C, respectively. To study deformation mechanisms and the role of surface condition on properties, specimens with different surface conditions (machined, polished, and electropolished) are tested. Two different loading rates of 0.2 mm/min and 0.5 mm/min are used to study the effect of loading rate on deformation and mechanical properties. Variations in weldment material properties are presented as a function of specimen surface conditions and loading speeds. Deformation behavior is studied on the side surfaces of tested micro-tensile specimens using SEM. Deformation is correlated to the microstructural constituent observed on side surfaces.

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