Mechanism of (Mg,Al,Ca)-oxide inclusion-induced pitting corrosion in 316L stainless steel exposed to sulphur environments containing chloride ion

Zheng, Shuqi; Li, Chunyu; Qi, Yi; Chen, Liqiang; Chen, Changfeng

doi:10.1016/j.corsci.2012.09.044

Cited by 202 publications

(68 citation statements)

References 51 publications

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“…Large oxides preferentially aligned to the rolling direction were found in the wrought material (2-4 μm diameters, Figure 3) which could be sites for pit initiation. [16][17][18][19] Oxides, enriched in Si and possibly Mn, were observed in the SLM 304L material ( Figure 5); however, these were of a much finer size scale (5-20 nm diameters). In the cellular regions, oxides precipitated preferentially at cell interfaces, as observed in Figure 5, whereas in the non-cellular regions, oxides precipitated throughout the material.…”

Section: Discussionmentioning

confidence: 99%

“…Preferential initiation of pits has been observed at oxide particles (Mg, Al, Ca-oxides with about 2-3 μm diameters) in 316L SS exposed to NaCl solutions. 18 The authors attributed the pit initiation to the lower potentials of the oxide particles as compared to the matrix. 18 The influence of inclusions on pitting corrosion has also been related to the size of the inclusions, where spherical sulfide inclusions smaller than d ≈ 280 to 1080 nm in 304L exposed to chloride solutions were not deleterious to the corrosion resistance.…”

Section: Discussionmentioning

confidence: 99%

“…18 The authors attributed the pit initiation to the lower potentials of the oxide particles as compared to the matrix. 18 The influence of inclusions on pitting corrosion has also been related to the size of the inclusions, where spherical sulfide inclusions smaller than d ≈ 280 to 1080 nm in 304L exposed to chloride solutions were not deleterious to the corrosion resistance. 16 The increased pitting potentials observed in the polished AM materials could be a result of the reduction in the size of the oxides present in the material as compared to the wrought 304L tested here.…”

Section: Discussionmentioning

confidence: 99%

“…3,[8][9][10][11][12][13] In conventional wrought 304L, inclusions, such as MnS or oxides, have been observed to reduce localized corrosion resistance by acting as sites for pit initiation, and could also pose an issue for SLM materials. [14][15][16][17][18][19] Regarding SLM materials, one study showed that a reduction in the size and distribution of MnS particles in 316L resultant from SLM processing actually enhanced its corrosion resistance relative to conventional wrought material. 4 However, the relationship between the porosity or inclusions in an SLM material and its pitting susceptibility is not always direct.…”

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confidence: 99%

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The Role of Microstructure and Surface Finish on the Corrosion of Selective Laser Melted 304L

Schaller

Mishra²,

Rodelas

et al. 2018

J. Electrochem. Soc.

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The corrosion behavior of selective laser melted (SLM) 304L was investigated and compared to conventional wrought 304L in aqueous chloride and acidic solutions. Through immersed electrochemical testing and exposure in acidic solutions, the SLM 304L exhibited superior pitting resistance in the polished state compared to wrought 304L. However, the surface condition of the SLM material had a great impact on its corrosion resistance, with the grit-blasted condition exhibiting severely diminished pitting resistance. Local scale, capillary micro-electrochemical and scanning electrochemical microscopy investigations, identified porosity as a contributing factor to decreased corrosion resistance. Preferential corrosion attack was not observed to be related to the characteristic underlying cellular microstructure produced through SLM processing. This study highlights the effects of SLM microstructural features on corrosion resistance, specifically the substantial influence of surface finish on SLM corrosion behavior and the need for development and optimization of processing techniques to improve surface finish. Powder bed selective laser melting (SLM) has become a desirable and widely used technique for the additive manufacturing (AM) of metal parts. While a significant amount of research has been carried out on the mechanical properties of SLM materials, little is known regarding their corrosion behavior. Of the few corrosion studies that do exist, the primary focus has been on evaluating general corrosion resistance.1,2 A few recent investigations have examined the role of processing and microstructure on the material corrosion behavior in more detail.3,4 However, there is still a need for further investigation in order to develop a full understanding of the microstructural and morphological characteristics inherent to AM materials due to the unique processing conditions and their relative contributions to the materials' corrosion behavior. Ideally, a ranking of the deleterious or advantageous properties formed in AM materials with respect to corrosion should be established. This is necessary for a variety of alloy systems in engineering relevant solutions and environments to help inform and guide future processing parameters, build designs, and materials selection.The powder bed process along with extremely high cooling rates and temperature gradients during SLM processing create microstructures and part surfaces that differ greatly from their conventional thermo-mechanically processed counterparts. Several characteristics are expected or have known effects on corrosion behavior including surface finish, porosity, inclusions (MnS, oxides, etc.), and microstructures formed through non-equilibrium cooling conditions. For example, a strong relationship between surface roughness and corrosion susceptibility has been observed in which pit initiation decreases with decreasing surface roughness in chloride solutions.5-7 Porosity, formed by entrapped gas or lack of fusion of powder particles in the SLM build, can also reduce...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

The Role of Microstructure and Surface Finish on the Corrosion of Selective Laser Melted 304L

Schaller

Mishra²,

Rodelas

et al. 2018

J. Electrochem. Soc.

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show abstract

“…Chiba et al observed that the metastable and stable pits were initiated at the MnS/steel boundaries [14]. Zheng et al [15] observed two types of inclusions in 316L stainless steel made of composite oxide inclusions of Ca, Mg, and Al, and alumina inclusions, respectively. Furthermore, they indicated that these two types of inclusions could trigger pitting corrosion in Cl − solution.…”

Section: Introductionmentioning

confidence: 99%

Pitting Corrosion of Steel Induced by Al2O3 Inclusions

Liu

Yang

Zhao

et al. 2017

Metals

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Abstract:To study the effect of Al 2 O 3 inclusions on pitting corrosion in steel, our researchers utilized industrial pure iron as the raw material with the addition of a proper amount of pure aluminum powder to form Al 2 O 3 inclusions. Corrosion experiments were performed by exposing the samples to a 6% FeCl 3 solution at room temperature (25 • C) for different lengths of time. Microscopic corrosion morphology was observed by scanning electron microscope (SEM), and the size change of the inclusions was quantitatively analyzed with Image Pro Plus. The experimental results showed that pitting corrosion arose preferentially around the Al 2 O 3 inclusions, and that pitting corrosion initiated at the junction of the Al 2 O 3 inclusions. The steel matrix dissolved and micro-cracks occurred as the Al 2 O 3 inclusions that were buried shallowly below the surface of the steel matrix promoted corrosion of the steel matrix. As corrosion progressed, the shallowly buried Al 2 O 3 inclusions began to appear on the surface, and the small, shallow inclusions fell off and formed micro pits. Furthermore, the clustered distribution of alumina inclusions had a greater effect on pitting initiation than the alumina inclusions distributed alone.

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Improvement on the pitting corrosion resistance of 304 stainless steel via duplex passivation treatment

Hou

Zhao

Cao

et al. 2019

Materials & Corrosion

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A remarkable improvement in the pitting corrosion resistance of 304 stainless steel was attempted using a novel duplex passivation treatment method. First, chemical passivation in nitric acid followed electrochemical passivation via potential polarization of step cycling in sodium nitrate electrolyte. Compared with traditional chemical passivation, breakdown potential was increased from 0.31 V SCE to positive than 0.9 V SCE at 70°C in a solution bearing 0.6 M [Cl − ] concentration. The critical pitting temperature was enhanced from 21.5°C to above 70°C in a solution with 6 M [Cl − ] concentration. Impedance analysis and X-ray photoelectron spectroscopy results show that a more compact passive film with a higher ratio of chromium oxide on iron oxide was achieved by electrochemical passivation compared with chemical passivation. Morphology observation suggested that the potential polarization of step cycling slightly increased the dissolution of inclusions after being subjected to chemical passivation. The probable reason for the improvement on pitting resistance is discussed in detail based on inclusion dissolution and the protectiveness in passive film. K E Y W O R D Schemical passivation, electrochemical passivation, pitting corrosion, sodium nitrate, stainless steel

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Mechanism of (Mg,Al,Ca)-oxide inclusion-induced pitting corrosion in 316L stainless steel exposed to sulphur environments containing chloride ion

Cited by 202 publications

References 51 publications

The Role of Microstructure and Surface Finish on the Corrosion of Selective Laser Melted 304L

The Role of Microstructure and Surface Finish on the Corrosion of Selective Laser Melted 304L

Pitting Corrosion of Steel Induced by Al2O3 Inclusions

Improvement on the pitting corrosion resistance of 304 stainless steel via duplex passivation treatment

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