Flash Tempering of High-Strength, Low-Alloy Martensitic Steel via Electrical Pulsing Treatment

Optimized heat treatment processes for high-strength, low-alloy steel are studied in order to maximize the strengthening effects of the alloying elements and achieve a favorable balance of strength and ductility. In this study, it is found that high-energy-density electric pulse treatment (EPT) can effectively reduce the residual stress in quenched high-strength, low-alloy steel. Furthermore, EPT promotes the precipitation of fine needle-like ε-carbides and small spherical M₆C carbides. Using an electrical pulse acting for 10 s with a current density of 19.52 A/mm², the elongation of the quenched steel increases from 4.5% to 12.4%. Compared to the as-quenched state, there is no significant decrease in tensile strength, while the product of strength and ductility reaches 20.33 GPa%. When the pulse current density is increased to 27.76 A/mm² for 10 s, the tempering effect is equivalent to that of tempering at 600 °C for 4 h.