Evaluation of Mechanical Properties and Microstructure of High-Strength Steel Walls Fabricated by Wire ARC Additive Manufacturing

This study investigates the microstructural and mechanical characteristics of a high-strength steel thin wall fabricated via wire arc additive manufacturing (WAAM). A 20-layer wall was produced using a bidirectional deposition strategy with fixed processing parameters to ensure repeatability. Microstructural analysis revealed significant spatial heterogeneity along the build direction. The bottom region exhibited the finest grain size (0.96±0.23 μm) due to the substrate heat sink effect, while the top region reveals the coarsest grain size (1.84±0.36 μm) due to slower cooling rates. XRD analysis confirmed the deposited material consists entirely of the ferrite phase. Mechanical testing showed a microhardness gradient ranging from 256±17.04 HV0.1 at the top to 288±16.78 HV0.1 at the bottom that directly correlates with grain refinement. Tensile tests revealed exceptional performance with ultimate tensile strength (UTS) exceeding 980 MPa, yield strength (YS0.2%) in range of 560–620 MPa, and elongation above 20%, meeting industrial requirements for structural applications. Fracture surface morphology confirmed a ductile micro-void coalescence mechanism, indicating high plastic deformation capability. These results demonstrate the WAAM capability to produce high-strength, structurally reliable steel components, supporting its application in large-scale manufacturing for shipbuilding, heavy engineering, and load-bearing structural systems.