Fracture behavior of high-strength bolts and connections in the whole process of fire

High-strength bolts have been widely used in steel bolted connections, and fire-induced high temperatures will affect its basic mechanical properties and fracture behavior, leading to failure of the connection and even collapse of the overall structure. Tensile experiments are conducted on Grade 10.9 high-strength bolts to investigate the effect of stress triaxiality and heating history on their mechanical and fracture properties in the whole process of fire. The true stress-strain curves are obtained to determine the material properties. The SMCS fracture model is calibrated based on test results, and parametric studies are conducted on fracture performance of T-stub connections in fire. The experimental results show that the SMCS model can effectively predict the fracture behavior of Grade 10.9 high-strength bolts for a stress triaxiality range of 0.3 to 1.2. There are three failure modes of T-stub connections under different temperature histories: yield fracture of flange plate, simultaneous yield fracture of flange plate and bolt, and yield fracture of bolt.</p

Creep behavior of Grade 10.9 high-strength bolts under and after fire

As an important component in steel connections, high-strength bolts have a high stress level and may experience creep deformation at high temperatures. This will lead to great deformation and even failure of steel connections, thus affecting progressive collapse resistance of steel structures. This paper experimentally and numerically investigates the creep behavior of 10.9 high-strength bolts under and after fire. The creep strain-time curves at different temperatures and stress levels were obtained using DIC measurement systems. The micromorphology and failure mechanism of high-strength bolts is examined by SEM. The Field & Field creep model is calibrated against test results, and parametric studies are conducted on T-stub connections. The experimental results show that the creep deformation of high-strength bolts is significant at high temperatures, and the creep strain is positively correlated with temperatures and stress ratios. The numerical results show that the Field & Field model is suitable for characterizing the creep behavior of high-strength bolts under fire situation. The fire resistance of T-stub connections is significantly affected by creep-related parameters. It is necessary to consider the effect of creep for predicting the behavior of high-strength bolts and steel connections, ensuring a safe design.</p

Mapping the Knowledge Domain of Corrosion Inhibition Studies of Ionic Liquids

Ionic liquids have received much attention in metal corrosion inhibition due to their unique properties of nontoxicity, low contamination, and high efficiency in corrosion inhibition. To fully understand the current status and latest progress of research in corrosion inhibition, we analyzed the literature using a systematic bibliometric method and visualization technology. The relevant studies specifically included co-occurrence analysis, cluster analysis, cocitation analysis, and keyword burst detection analysis. The results show that Asian countries, led by China, constitute the central research force in this ionic liquid corrosion inhibition field. Materials science, applied physics, and applied chemistry were the core disciplines in this research field, and the Journal of Molecular Liquids, Corrosion Science, Electrochim Acta, and Industrial & Engineering Chemistry Research were the core journals. The hot research topics in this field had been roughly divided into five timelines, representing five research topics: ionic liquid, solution, corrosion resistance, corrosion inhibitor, and film. The ionic liquid corrosion inhibition field has many research directions and a wide range of frontier branches. Among them, electrochemistry, molecular simulation, and electrolyte solutions have become the frontier of ionic liquid corrosion inhibition research