| Abstract Scope |
The growing demand for natural gas and oil has increased the use of HSLA steels, where controlling ductile fracture propagation is a critical challenge, making accurate estimation of fracture resistance essential for safe pipeline operation. A comprehensive experimental and analytical methodology was used to study microstructural damage leading to fracture in four precipitation-strengthened HSLA steel grades (Gr80Nb, Gr80Ti, Gr100, Gr100Ti). Strain partitioning, which contributes to damage evolution, was quantified using in-situ tensile testing under a scanning electron microscope (SEM) and local strain mapping with digital image correlation (DIC). This technique identifies void nucleation and growth mechanisms like particle separation, hard particle cracking, and decohesion. The results show that Gr80Ti and Gr100Ti exhibit an increasing strain partitioning gradient, undesirable for damage accumulation, while Gr80Nb and Gr100 show a decreasing trend. The strain partitioning measured for Gr80Ti and Gr100Ti exhibited reduced strain partitioning gradients, which will reduce damage accumulation. |