Investigation on the nickel content design and the corrosion resistance of low alloy steel welded joint in tropical marine atmosphere environment

Abstract

In this study, three kinds of welding materials (WMs) with different Ni contents were designed for low alloy steel welded joints made by CO2 gas‐shielded welding technique. The corrosion resistance of welded joint was studied through the atmosphere exposure test in Trat, Thailand. Results show that there was a hardening in the heat‐affected zone after welding, and the average hardness slightly increased with the increase of Ni in WM. The electrochemical activity at the fusion line zone enhanced with the addition of Ni in WM, indicating a more obvious local galvanic corrosion effect there. Ni promoted the generation of NiFe2O4 and the transformation from γ‐FeOOH to α‐FeOOH, which increased the impedance modulus of the rust film on WM. More important, the corrosion performance assessment illustrated that the addition of Ni in WM hardly had an effect on the corrosion step values after half a year test, which confirmed that there is no need to add excessive content of Ni.

Attempt to Optimize the Corrosion Resistance of HRB400 Steel Rebar with Cr and RE

“…The spectrum of Cr 2p3/2 is composed of Cr 2 O 3 (574.8 ± 0.1 eV) and Cr(OH) 3 (577.4 ± 0.1 eV). In general, the higher the valence state of the metal element, the more difficult it is to continue to oxidize it [20,21]. The results show that Cr and Fe exist in the form of Cr 3+ , Fe 2+ , and Fe 3+ in the passive film, respectively, which indicates the critical roles of Cr 3+ and Fe 3+ on the protectiveness of the passive film.…”

“…To obtain the phase composition of the three steel rebars after the dry/wet cyclic tests, the XRD results of 7 and 15 days are presented in Figure 13. In both corrosion cycles, the crystalline phase of the rust layer consisted of α-FeOOH, γ-FeOOH, and Fe3O4 [20,21]. There was not a significant difference in the physical phase, which should be related to the low addition of alloying elements, while the intensity of the α-FeOOH increased with the addition of Cr and RE, which indicates that Cr and RE promoted the formation of α-FeOOH.…”

“…In addition, with the decrease of the pearlite in the RE, the band-like structure in the steel rebar also significantly decreased. The previous study indicated that the RE element could reduce the activity of carbon in ferrite and increase the ability of ferrite to dissolve carbon, thereby changing the relative content of ferrite and pearlite [20,21]. Eventually, it could improve the comprehensive properties of steel rebars such as strength and plasticity.…”

“…Materials 2022, 15, x FOR PEER REVIEW 3 of 18 time of 50 min was allowed prior to the EIS measurement. EIS measurements were performed over the frequency range from 100 kHz to 10 mHz with a 10 mV sinusoidal amplitude at open-circuit potential (OCP), and the data were fitted with ZSimpWin 3.3 software [20,21]. All tests were conducted in the Ca(OH)2 + 1 wt.% NaCl solution.…”

Galvanic Corrosion and Fatigue Behavior of a SM480C Welded Joint Steel in a Sea-Crossing Suspension Bridge

“…Fe(OH) 2 can further react to form other oxy-hydroxides, such as α-FeOOH, γ-FeOOH, and δ-FeOOH [28,29].…”