Effect of electrode melting rate control strategy on macrosegregation behavior and microstructure characterization during electroslag fusion welding
摘要
Electroslag fusion welding (ESFW) is a secondary electroslag metallurgical technology specifically developed to overcome the challenges of joining large-section special steel components. However, the effect of electrode melting rate control strategy on its microstructure and macrosegregation remains unclear. The influence of constant electrode melting rate strategies on the macrosegregation behavior of carbon, molybdenum, and chromium in ZG04Cr13Ni5Mo steel, as well as the microstructural characteristics of the fusion welding zone (FWZ), is investigated through combined experimental and numerical simulation methods. The results show that the constant melting rate control significantly improves the homogeneity of macrosegregation. Specifically, at a melting rate of 2.259 kg min−1, the carbon segregation index at the central axis of FWZ decreases to 4.4%, and the spatial distribution uniformity of Mo and Cr is also optimized. Microstructure analysis indicates that the local solidification time (LST) directly affects the phase transition, secondary dendrite arm spacing, and grain size of ESFW. A higher melting rate can reduce LST, decrease martensite distortion caused by macrosegregation, continuously refine grains, and alleviate the formation of banded martensite. The power law relationship between the LST and martensite size of ZG04Cr13Ni5Mo steel is also obtained.