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ASTM A694 F65 is a low-alloy steel valued for its high yield strength, good weldability, and excellent toughness at low temperatures. Owing to its balanced strength and impact resistance, it is extensively employed in the production of flanges and fittings for low-temperature, high-pressure service, where tensile strength and corrosion resistance are not the primary design requirements. This study examines the effect of heat treatment parameters, specifically the type of heat treatment and cooling conditions, on the microstructural and mechanical properties of an industrial hot-forged ASTM A694 F65 steel. Microstructural evolution was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy in Secondary Electron mode (SEM-SE), while mechanical behavior was evaluated through microhardness measurements and tensile testing. Experimental results regarding phase composition, morphology and distribution, lattice strain, yield strength, ultimate tensile strength, elongation at fracture, and microhardness were systematically analysed in relation to the applied heat treatment and cooling regime. Based on the results obtained, double normalizing is recommended for hot-forged A694 F65 steel, with sand cooling for thin-walled components and air cooling for thick sections, to prevent excessively low cooling rates and the formation of undesirable banded microstructures. Acknowledgments This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CCCDI-UEFISCDI, project number PN-IV-P7-7.1-PED-2024-2368, contract number 96PED / 29.05.2025, within PNCDI IV.
Keywords: heat treatment, microstructural evolution, mechanical properties, cooling conditions, steel.© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.