Transverse tensile samples were extracted from the centreline position of three different compositions of uncoated thick walled microalloyed X70 UOE pipe at a location 180° from the weld. Aging heat treatments of 5, 15, and 25 minutes and temperatures of 175, 215, and 255°C were applied. Tensile tests were conducted on both the original pipe and on pre-strained samples. Microstructural analysis was undertaken using optical microscopy and scanning electron microscopy (SEM). The effects of a combined time and temperature aging parameter, pre-strain, microstructure and tensile work hardening behaviour on the pipe yield stress and yield to tensile strength ratio, is presented.

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