Passivation performance of Nb microalloyed rebar in concrete carbonation environments with different pH.

In this study, XPS sputtering depth, SEM and electrochemical tests (CV, EIS, M-S, i-t, DPP) were used to study the structural composition and formation mechanism of surface passive film of Nb microalloyed rebar in SCPS with different pH. The results showed that after passivation for 10 d in SCPS with different pH, compared with CS rebar, the stability and compactness of surface passive film of 34Nb rebar gradually increased with the decreases of pH. Firstly, with the decreases of pH, the outer layer of surface passive film of 34Nb rebar was composed of Fe oxides and Fe hydroxides, and the inner layer was composed of Fe oxides and Nb oxides, thus increasing the mass ratio of Fe/Fe and NbO/(NbO + NbO).

Effect of Ce on structural evolution and corrosion resistance of HRB500E rebar corrosion layer.

HRB500E rebar is a low-alloy high-strength steel with excellent mechanical properties and good plasticity but suffers from deficient corrosion resistance. This can be solved by adding trace elements, including rare earth elements. Herein, the corrosion-resistant behavior of rebar was evaluated by weightlessness testing and electrochemical measurements, and the effects of Ce on the structural evolution of the corrosion product layer were investigated by scanning electron microscopy (SEM), Electron Probe X-ray Micro-Analyzer (EPMA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS).

Effect of Controlling Nb Content and Cooling Rate on the Microstructure, Precipitation Phases, and Mechanical Properties of Rebar.

Seismic anti-seismic rebar, as materials for supporting structures in large buildings, need to have excellent mechanical properties. By increasing the Nb content and controlling the cooling rate, the microstructure and precipitation behavior of the steel are adjusted to develop seismic anti-seismic rebar with excellent mechanical properties. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and a universal tensile testing machine were used to characterize the microstructure, precipitation phases, and mechanical properties of the experimental steels.

Influence of V on the Microstructure and Precipitation Behavior of High-Carbon Hardline Steel during Continuous Cooling.

High-carbon hardline steels are primarily used for the manufacture of tire beads for both automobiles and aircraft, and vanadium (V) microalloying is an important means of adjusting the microstructure of high-carbon hardline steels. Using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM), the microstructure and precipitation phases of continuous cooled high-carbon steels were characterized, and the vanadium content, carbon diffusion coefficient, and critical precipitation temperature were calculated. The results showed that as the V content increased to 0.