Study On The Axial Compression Performance Of Stainless Steel Circular Tubular Columns Fabricated By Wire And Arc Additive Manufacturing

Wire and arc additive manufacturing(WAAM)offers advantages such as high deposition rates,low manufacturing costs,and minimal limitations in forming size,making it suitable for the construction of large-scale metal components in the field of construction.However,WAAM technology is still in its infancy in construction industry,with challenges such as material properties,structural performance,geometric accuracy,quality assurance,and standardization.This study investigated the fundamental mechanical properties and microstructures of WAAM 316 L austenitic stainless steel and the axial compression performance of WAAM stainless steel circular tubular stub columns and long columns.Cold metal transfer WAAM was employed to prepare 316 L austenitic stainless steel deposition plates with different deposition paths.Tensile specimens were prepared from the plates along different sampling directions,and tensile tests,metallographic tests,and fracture scanning electron microscope(SEM)tests were conducted.The results showed that the material had acceptable strength but lower-than-standard ductility,and exhibited apparent anisotropy.Deposition paths had a certain impact on the material properties.Metallographic tests demonstrated a typical austenite microstructure.The size of the crystals,which affected mechanical properties,was influenced by the deposition paths.Fracture SEM tests revealed a dimple fracture morphology,indicating a ductile fracture mechanism.The mechanical properties were correlated with the fracture morphology.Solution heat treatment increased the material’s ductility but reduced its strength.A set of circular tubular stub columns and a set of circular tubular long columns with different cross-sectional dimensions,wall thicknesses,and heights were fabricated using WAAM technology.Geometric measurements were performed using 3D laser scanning to determine the basic geometric parameters and geometric imperfection.Axial compression tests were conducted to obtain load-end shortening curves for stub columns and load-deflection curves for long columns.Failure modes,load bearing capacity,and influencing factors were analyzed.Finite element models were established and validated for stub columns and long columns.Experimental data was expanded through numerical simulations to cover a broader range of local and overall slenderness ratios.Finally,the experimental and simulation results were compared against the strength predictions of current design specifications.The results indicated that,compared to conventionally built steel tubular columns,the WAAM components exhibited larger geometric irregularity and geometric imperfections.In axial compression tests,all WAAM circular tubular stub columns experienced local buckling,while long columns experienced overall(or local-overall interactive)buckling.The load bearing capacity of WAAM circular tubular stub columns generally decreased with increasing local slenderness and local geometric imperfection,while that of long columns decreased with increasing overall slenderness and overall geometric imperfection.The established finite element model could effectively simulate the axial compression performance of WAAM circular tubular columns.Current design codes were not fully applicable to WAAM components.Compared to European and American codes for steel structure design,the Chinese code had higher strength prediction for load bearing capacity.The load bearing capacity obtained from experiments and simulations did not fully meet the strength prediction specified by the Chinese code.In summary,this study provided valuable information for the application of WAAM technology in the field of construction,clarified key issues in material properties,geometric accuracy,axial compression performance,and design code applicability.This study laid a foundation for further research and code development.