In 2021, the Steel Construction Institute (SCI) began a research project to investigate the structural performance of laser welded profiles in comparison with extruded/hot rolled austenitic stainless steel sections.
Rationale
Prior research on stainless steel structural members has mostly focused on fabricated or conventionally welded sections. There has been very little structural tests on extruded or hot rolled sections and the ones completed, mostly focused on stainless steel angles. With stainless steel structural shapes like beams, channels, tees, and HSS increasing in popularity, more information was needed to assist with designs involving these profiles.
One of the disadvantages of fabricated shapes built by traditional welding is that the high heat input from traditional welding causes residual stresses that reach a high proportion of the yield strength. This causes a negative impact of the buckling strength of the section. Fortunately, the automated laser welding process can control and reduce the amount of heat applied to the section creating significantly lower residual stresses and superior structural performance over conventionally welded shapes.
For this project, The SCI collaborated with the Czech Technical University in Prague. The goal of the experiments was to assess the structural performance of austenitic stainless steel laser welded and extruded/hot rolled sections of equivalent sizes.
Material and Testing
The testing included laser welded and extruded I-Beams (S5x10) and laser welded and hot rolled channels (UAP120x60). Specific factors that affect the structural performance of sections were measured including: material properties, cross-sectional geometries, residual stresses, and geometric imperfections. Column tests were also performed to determine and compare the strengths achieved by laser welded and extruded/hot rolled sections.
Discussion
The outcome of the experimental campaign highlighted that residual stresses and geometric imperfections are very similar in laser welded and extruded/hot rolled profiles. Consequently, the laser welded and extruded/hot rolled sections exhibit similar buckling responses. This was confirmed with the findings from the column testing which showed that the structural response of the laser welded I-beam was superior to the equivalent extruded section. In addition, the residual stresses in the laser welded I-beams were well below that of the conventionally welded I-beams and geometric imperfections were well below the maximum allowable fabrication tolerances.
Conclusion
This study demonstrates with objective evidences that the structural performance of austenitic stainless steel laser welded sections is equivalent to that of extruded/hot rolled sections. This outcome is of great interest for engineers, architects and designers who design with structural stainless steel. As the only domestic producer of laser welded stainless and carbon steel profiles, Stainless Structurals is excited to share this news with our customers. Please visit our “Resources” page for a summary of this experiment as well as other useful tools such as section properties, Revit files, design tables and more. Contact our team today for more information on how laser welded profiles are the perfect solution for your next project.
