The microstructure and fracture performance of four microalloyed linepipe steels (A, B, C, and D) were investigated. Steels A, B, and C were recently manufactured, while steel D was about 30 years old. Simulated CGHAZ specimens were produced by the Gleeble technique using thermal cycles relevant to linepipe welding procedures. The base metals and simulated HAZs were subjected to a variety of toughness tests including instrumented precracked Charpy (IPC) and standard Charpy-V-notch (CVN) tests. Full transition curves were generated, and transition temperature was used as a measure of cleavage resistance. Upper shelf energy was used as a measure of ductile fracture resistance.