Effect of Molybdenum on the Corrosion of Low Alloy Steels in Synthetic Seawater

Shin, Seungwook; Song, Sol-Ji; Shin, Young-Woong; Kim, Jung-Gu; Park, Byung-Joon; Suh, Yong-Chan

doi:10.2320/matertrans.m2016222

Cited by 10 publications

(4 citation statements)

References 55 publications

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“…8 . It is also worth noting that Mo addition improves the resistance to corrosive environment other than HE 30 , 31 . In conclusion, Mo carbide was the ideal alloying element for enhancing HE resistance for applications in corrosive environments.…”

Section: Discussionmentioning

confidence: 99%

Comparative study on the effects of Cr, V, and Mo carbides for hydrogen-embrittlement resistance of tempered martensitic steel

Lee

Mun

et al. 2019

Sci Rep

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In this study, the ideal alloying element (among Cr, V, and Mo carbides) to enhance the resistance to hydrogen embrittlement (HE) in a tempered martensitic steel was investigated. Four types of steels were designed to contain cementites, Cr-rich M7C3 carbides, V carbides, and Mo carbides, respectively. These steels were tailored to possess a comparable tensile strength (~1.6 GPa). The HE resistances of these steels were evaluated through the slow strain rate test and cyclic corrosion test. The results showed an enhanced HE resistance, characterized by a high notch fracture strength after hydrogen charging, in the samples containing V carbides and Mo carbides. In particular, Mo carbide was regarded as the most ideal alloying element for HE resistance because of the high resistivity parameter, inhibited hydrogen penetration, and suppressed strength loss by internal hydrogen.

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Section: Discussionmentioning

confidence: 99%

Comparative study on the effects of Cr, V, and Mo carbides for hydrogen-embrittlement resistance of tempered martensitic steel

Lee

Mun

et al. 2019

Sci Rep

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“…Because the derived values of n were less than 1 (see Table 3 ), this system at the interface deviated from an ideal capacitance, and the depression angle (α) can be quantified as follows [ 23 , 24 ].

…”

Section: Resultsmentioning

confidence: 99%

“…Considering that the increase in α (derived from n scale ) could be ascribed to the heterogeneity of the surface by increasing the surface roughness and forming the porous layers [ 24 , 25 ], a much smaller α (APIX70: 0.116, 9Ni: 0.088, and 24Mn3Cr: 0.076) for the 24Mn3Cr sample with a prolonged immersion time could also suggest that the sample may have had surface inhibiting properties with a comparatively higher level of homogeneity and a smaller level of porosity. An interesting point which is different from the measurements in a neutral condition reported previously [ 1 ] is that a longer incubation time was required to ensure the comparatively higher corrosion resistance of the 24Mn3Cr sample in an acidic environment.…”

Section: Resultsmentioning

confidence: 99%

Long-Term Corrosion Behavior of Strong and Ductile High Mn-Low Cr Steel in Acidic Aqueous Environments

et al. 2022

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To expand the industrial applicability of strong and ductile high Mn-Low Cr steel, a deeper understanding and mechanistic interpretation of long-term corrosion behavior under harsher environmental conditions are needed. From this perspective, the long-term corrosion behaviors of 24Mn3Cr steel under acidic aqueous conditions were examined through a comparison with conventional ferritic steels using the electrochemical measurements (linear polarization resistance and impedance), and immersion test followed by the metallographic observation of corrosion morphologies. In contrast to conventional ferritic steels, 24Mn3Cr steel, which had the lowest corrosion resistance at the early immersion stages (i.e., the highest corrosion current density (icorr) and lowest polarization resistance (Rp)), showed a gradual increase in corrosion resistance with prolonged immersion. Owing to the slow formation kinetics of (Fe,Cr)-enriched oxide scale, a longer incubation time for ensuring a comparatively higher corrosion resistance is required. On the other hand, conventional ferritic steels had an oxide scale with less densification and a lower elemental enrichment level that did not provide an effective anti-corrosion function. From the results, this study can provide significant insight into the industrial applicability of the high Mn-low Cr steel by providing the mechanistic interpretation of corrosion behaviors in acidic aqueous environments.

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“…XPF800's microstructure is fine-grained, single-phase ferrite with a dispersion of very fine vanadium and molybdenum carbides. Molybdenum, whilst forming carbides that contribute substantially to precipitation hardening in this steel, has also been shown to form MoO4 2oxides within the rust layer for low-alloy steels of very similar composition immersed in NaCl electrolyte, which are capable of resisting aggressive chloride ions [234], as should also be the case for XPF1000. Where passivity is a consideration, grain refinement (XPF1000 has a smaller grain size than XPF800) is thought to provide a more protective film [235], however grain (or phase) boundaries tend to have higher energy (and electron activity) than occurs within grains, increasing the overall reactivity of the surface [236].…”

Section: Open Circuit Potentialmentioning

confidence: 63%

Hydrogen Embrittlement of Automotive Ultra-High-Strength Steels: Mechanism and Minimisation

Lelliott¹

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Automotive manufacturers are increasingly using ultra-high-strength steels in vehicle components to facilitate mass reduction via downgauging. Unfortunately, as the strength of steels increases, so does susceptibility to ‘hydrogen embrittlement’, a process in which ductility is significantly impaired by ingress of hydrogen. Mechanisms and environmental conditions by which this degradation occurs are not fully understood. In this work, 2 fully-ferritic, 2 fully-martensitic boron, and 2 ferrite-martensite dual-phase, ultra-high-strength steels, were assessed for susceptibility to hydrogen embrittlement via 3 key characteristics: firstly, with particular regard to hydrogen evolution under corrosion conditions, through well-established open circuit potential and potentiodynamic polarisation experiments. Exacerbation of hydrogen evolution through galvanic corrosion of a zinc coating was assessed by scanning vibrating electrode technique (SVET), and an attempt made to quantify increased risk of hydrogen evolution during crevice corrosion through a novel time-lapse photography experiment. Secondly, hydrogen diffusivity was assessed via permeation experiments. Finally, degradation in mechanical properties due to diffusing hydrogen was evaluated through slow strain rate tests (SSRT), whereby susceptibility to embrittlement was equated to reduction in ductility of hydrogen-charged test specimens. The fully-ferritic steels showed the greatest resistance to mechanical degradation, attributed to micro-alloy nano-precipitates within their microstructure acting as ‘traps’, leading to lower diffusivity compared to dual-phase steels of equivalent strength. Indeed, lower diffusivity showed a strong correlation with lower levels of embrittlement across all steels. 1000 MPa dual-phase steel showed the greatest degradation in mechanical properties, with fully-martensitic boron steels also found to be particularly susceptible. 1000 MPa dual-phase steel also showed the largest increase in hydrogen evolution reaction in response to polarisation, thought to result from the inherent potential difference between ferrite and martensite phases. Galvanic corrosion of a damaged zinc coating was found to polarise the exposed steel substrate, triggering sufficient hydrogen evolution to reach critical concentrations for embrittlement.

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Effect of Molybdenum on the Corrosion of Low Alloy Steels in Synthetic Seawater

Cited by 10 publications

References 55 publications

Comparative study on the effects of Cr, V, and Mo carbides for hydrogen-embrittlement resistance of tempered martensitic steel

Comparative study on the effects of Cr, V, and Mo carbides for hydrogen-embrittlement resistance of tempered martensitic steel

Long-Term Corrosion Behavior of Strong and Ductile High Mn-Low Cr Steel in Acidic Aqueous Environments

Hydrogen Embrittlement of Automotive Ultra-High-Strength Steels: Mechanism and Minimisation

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