Abstract:
Fire-Resistant Steels (FRS) are widely used to ensure building stability during fire incidents, enabling safe evacuation. In this study, a FRS alloyed with Nb, Mo, B, and Ti was cast, thermomechanically processed, and aircooled to achieve the “as received” condition. The yield strength (YS) was evaluated through tensile tests at room temperature (YS RT) and at 600 ◦C (YS 600 ◦C), along with a constant pre-load test at high temperatures. A FireSimulation (FS) test was subsequently conducted using a quenching dilatometer. Thermodynamic analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Atom Probe Tomography (APT) were used to characterize the samples. The tensile tests revealed a YS ratio YS(600◦ C) YS RT of 0.76, exceeding the requirement set by the Japanese Code. TEM analysis identified (Nb, Ti, Mo)C precipitates ≈ 20 nm in the asreceived condition, consistent with thermodynamic predictions. After the fire simulation test, additional (Nb, Ti)C carbides ≈ 10 nm were observed. APT revealed that Nb and C atoms were aligned along dislocations or subgrain structures under simulated fire condition, whereas these atoms were sparsely distributed in the asreceived condition. The formation of NbC nanoprecipitates, influenced by the presence of Mo, Ti, and B atoms, provides valuable insights into the enhancement of fire-resistant material.
Referência:
BAURI, L.F.; FERREIRA, A.M.; ARIZA-ECHEVERRI, E.A.; CARVALHO, Felipe Moreno Siqueira Borges de; HOMES, P.M.C.F.; SONKUSARE, R.; LU, Y.; TSCHIPTSCHIN, A.P.; GOLDENSTEIN, H. New fire-resistant steel alloyed with Nb-Mo-B-Ti: mechanical properties and characterizaton via SEM, TEM, and APT. Materials Characterization, v.225, 115104, 9p., 2025.
Acesso ao artigo no site do Periódico:
https://www.sciencedirect.com/science/article/abs/pii/S1044580325003936
