August 2021, Vol. 248, No. 8
Features
Live Mapping of HAZ Softening in Pipeline Seam, Girth Welds
By Mahyar Asadi, Advanced Welding Engineer, Applus Engineering Canada Modern pipeline grades, such as X70 and X80, improve many properties but come with undesirable features such as heat-affected zone (HAZ) softening in seam and girth welds. Figure 1 These pipeline steels with microalloying elements are manufactured using thermomechanical controlled processing (TMCP) with controlled rolling and cooling for improving mechanical properties. When pipelines are welded together, the HAZ material adjacent to the weld pool experiences an irregular thermal profile resulting in adverse microstructural evolution. This relatively small

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