An Initial Report on the Structure-Property Relationships of a High-Strength Low-Alloy Steel Subjected to Advanced Thermomechanical Processing in Ferrite
2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Advanced thermomechanical processing (aTMP) of high-strength low-alloy (HSLA) steels has been applied to achieve ultrafine ferrite grains decorated with nanoscale precipitates, clusters, and solute segregation, potentially leading to an increase in strength, toughness, and ductility. In our own previous research on a modern Mo-Ti-Nb HSLA steel processed in ferrite, this was only confirmed using hardness testing. Reports on the success of similar aTMP routes in achieving superior mechanical properties so far only provided results from subsize specimens or simpler steels under large strain conditions. Therefore, herein, an initial report on the mechanical properties of the previously studied Mo-Ti-Nb HSLA steel subjected to warm rolling and aging is provided. A reduction of 55% at 650 °C leads to an ultimate tensile strength (UTS) of 650 MPa, a yield to an ultimate tensile strength ratio of 0.95, and a total elongation of 14% in the as-rolled condition, similar to mild steels deformed to larger strains. The low yield to UTS ratio is explained by precipitate coarsening. Delamination occurs in the low-temperature region of Charpy impact testing in both longitudinal and transversal directions. Direct aging significantly increases the room temperature impact energy due to the onset of grain growth.