Abstract
In order to protect low-alloy steel from corrosion in outdoor applications, it is common practice to use surface treatments e.g. painting or galvanization. The costs of these specific treatments and further maintenance can be reduced by exploiting weathering steel, the so-called CORTEN steel. The rust of this material forms a protective layer, adherent and self-regenerative, capable to stop the oxidation of the raw material. This characteristic, called self-passivation, is achieved by adding Cu, Cr and P in the alloy. Furthermore, its natural rust-color inspired architects, artists and civil engineers that start using CORTEN for bridges, building facades, artworks etc.. The harmony of CORTEN with natural environments boosts its application for guardrails (safety barriers) along the highway and alpine roads of the South-Tyrolean region. These components, in addition to aesthetic characteristics, have to fulfill safety requirements, especially during crash events. During an impact, the main goal of guardrails is to absorb and dissipate energy. Large deformations take place. Therefore, the most important mechanical characteristic for guardrails’ materials is the tenacity related to the ductile behavior. However, despite CORTEN guardrails are homologated through experimental tests, in some specific conditions the passivation process could fail. Therefore, its energy absorption capabilities can be jeopardized by corrosion. In order to verify and/or optimize specific guardrails’ geometries for safety applications, it is important to be able to model the ductile behavior and fracture locus of CORTEN within finite elements.
The goal of this paper is to characterize the ductile behavior of CORTEN through experimental quasi-static tests with different geometries, thus different level of triaxiality. The test configurations were numerically reproduced, to retrieve the actual stress state, quantify the plastic strain at failure and calibrate a ductile damage model.