Mn-Depleted Zone Formation in Rapidly Cooled High-Strength Low-Alloy Steel Welds

The mechanism of formation of an Mn-depleted zone (MDZ) near the inclusion in a steel weld was elucidated based on quantification of MDZ depth and thermodynamic calculations. The effective inclusion phase for intragranular nucleation, which increased as a function of increasing chemical driving force, satisfied the requirements for presence of a considerable quantity of Mn in the phase, and a lower precipitation temperature compared with the solidus temperature of the matrix.This work was supported by the Fundamental R&D Program for the Core Technology of Materials (K0006030, Development of joining materials by the control of phase transformation and critical energy) funded by theMinistry of Trade, Industry & Energy (MI, Korea)