Effect of heat treatment processes on mechanical properties and microstructure of of AH460 marine engineering steel

The effect of the short R-Q-T (Rolling-Quenching-Tempering) process on the microstructure evolution of AH460 offshore engineering steel was studied through high-temperature deformation experiments and heat treatment analysis. The steel underwent theoretical calculations and multi-scale characterization to quantitatively evaluate its microstructure and precipitation behavior. A thermodynamic and kinetic model was established to analyze V(C,N) precipitation in ferrite, determining an optimal holding temperature of 600 ℃. The microstructure and phase composition were characterized using metallographic microscopy, X-ray diffractometry, and high-resolution transmission electron microscopy, while EDS, FFT, IFFT, and SAED diffraction confirmed that the precipitated phase was V(C,N). The results demonstrated that the short R-Q-T process produced a finer, more uniform microstructure, while the size and quantity of precipitated phases increased with tempering time. The V(C,N) phase played a role in grain refinement during deformation and cooling and contributed to precipitation strengthening at room temperature. The combination of these mechanisms ensured the mechanical properties of AH460 steel, making the short R-Q-T process an effective method for improving its microstructure and strength.