Effect of Mn Content on Microstructure and Mechanical Properties of Weld Metal During High Heat Input Welding Processes

摘要

To elucidate the effect of Mn content on the microstructure and mechanical properties of weld metal, flux-cored wires with three different Mn contents were prepared to conduct high heat input welding experiments. Complex inclusions and Mn-depleted zones were observed in the weld metal with heat input of 85 kJ/cm. The study indicated that complex inclusions enabled nucleation of acicular ferrite with interlocking structure, leading to enhanced impact toughness. With decrease in Mn content, the number of complex inclusions with Mn-depleted zone and the volume fraction of acicular ferrite were both decreased. Additionally, the impact toughness of weld metal was significantly degraded with lower Mn content present in martensite-austenite (M-A) constituent and bainite.