Abstract: The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite (IAF) using micron-sized inclusions and restricting the growth of prior austenite grains (PAGs) by nanosized particles during welding. The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel, resulting in high impact toughness. This work summarizes the combined effect of deoxidizers and alloying elements, with the aim to provide a new perspective for the research and practice related to improving the impact toughness of the heat affected zone (HAZ) during the high heat input welding. Ti complex deoxidation with other strong deoxidants, such as Mg, Ca, Zr, and rare earth metals (REMs), can improve the toughness of the heat-affected zone (HAZ) by refining PAGs or increasing IAF contents. However, it is difficult to identify the specific phase responsible for IAF nucleation because effective inclusions formed by complex deoxidation are usually multiphase. Increasing alloying elements, such as C, Si, Al, Nb, or Cr, contents can impair HAZ toughness. A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation. Si, Cr, or Al addition leads to the formation of undesirable microstructures. Nb reduces the high-temperature stability of the precipitates. Mo, V, and B can enhance HAZ toughness. Mo-containing precipitates present good thermal stability. VN or V(C,N) is effective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite. The formation of the B-depleted zone around the inclusion promotes IAF formation. The interactions between alloying elements are complex, and the effect of adding different alloying elements remains to be evaluated. In the future, the interactions between various alloying elements and their effects on oxide metallurgy, as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.