LAUSR

The mechanism for refining grains in industrial EH460 heavy‐gauge steel with a thickness of 80 mm and above is investigated using electron backscattered diffraction. Charpy impact and drop‐weight tests are conducted to quantify the effect of microstructures and texture on low‐temperature toughness. Abundant ferrite grains that form and impinge from different prior‐austenite grains increase the high‐angle grain boundary (HAGB) fraction. The result is a refined effective grain size of 3.7 ± 4.2 μm, a high HAGB fraction of 62.1%, and an average Charpy impact absorbed energy of ≈209 J at −80 °C. The excellent impact toughness is due to the high intensity of texture with types of {113}−{112}<110> and {332}<113>, as well as the uniformly distributed {110} slip planes and {001} cleavage planes. The high intensities of {110}<111> and {110}<112> also improve the drop‐weight toughness. However, due to plastic constraint in the larger drop‐weight specimens, increased plane strain in the inner regions is the root cause of the brittle fracture of these specimens at −70 °C. Nevertheless, the improved drop‐weight performance is attributed to the plane stress deformation at the specimen edges and also the occurrence of delamination in the central section.