Investigation on Fracture Behavior of Electroslag Welding Joint with High-Performance Steel

This study aimed to investigate fracture behavior of electroslag welding (ESW) joint with 590-N/mm² class steel using numerical analysis, covering a range of material scales in the structural level. The extended Mohr–Coulomb (EMC) fracture criterion was employed for finite element analysis (FEA). Uniaxial tensile test and three-point bending test were conducted to analyze the fracture behavior from the material scale and calibrate the fracture criterion. The test specimens consisted of the base metal, heat-affected-zone metal, and welding metal obtained from an ESW joint with a 590 N/mm² class steel. Subsequently, FEA was conducted for a biaxial tensile test to investigate fracture behavior at a structural scale and verify the feasibility and accuracy of the calibrated fracture criterion. The comparison between the results from the FEA and test suggests that the FEA based on the EMC fracture criterion can accurately predict fracture behavior but tends to overestimate the bearing capacity. Thereafter, the effect of axial force on column was quantitatively investigated. The results suggest that the existence of tensile axial force at column decreases the ductility of ESW joint and shifts the fracture locus from the welding metal to heat-affected zone. However, the force has minimal influence on the pop-in load. Finally, the feasibility of applying the current Japanese specifications designated for the 490 N/mm² class steel for the 590 N/mm² class steel was examined. The results indicate that the provision can serve as a safe and reliable guideline for the 590 N/mm² class steel as well.