The composition of the boundary region of MnS inclusions in stainless steel and its relevance in triggering pitting corrosion

Schmuki, Patrik; Hildebrand, H.; Friedrich, A.; Virtanen, Sannakaisa

doi:10.1016/j.corsci.2004.05.023

Cited by 189 publications

(92 citation statements)

References 25 publications

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“…Experimental observations indicate in many cases that corrosion pits initiate at the inclusion/matrix boundaries. Moreover, the highest electrochemical reactivity of the inclusion/matrix in comparison to the steel matrix and the inclusion itself has been reported [6,7]. The shape, composition and distribution of inclusions have significant effects on the corrosion resistance, too.…”

Section: Introductionmentioning

confidence: 99%

“…Park et al [6] observed inclusions such as MnS, AlN, Al 2 O 3 , MnAl 2 O 4 and other complex inclusions in Mn-Al steels. Previous studies [7][8][9] demonstrated that non-metallic inclusions, especially sulfide inclusions affect the corrosion resistance of steel by providing pitting sites. Presence of MnS inclusions drastically increases corrosion current density and shifts corrosion potential to more negative values.…”

Section: Introductionmentioning

confidence: 99%

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Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

Grajcar

Grzegorczyk

Kozłowska

2016

Archives of Metallurgy and Materials

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CorrosIon rEsIstanCE and pIttIng bEhavIour of low-Carbon hIgh-Mn stEEls In ChlorIdE solutIonCorrosion resistance of the X4MnSiAlNbTi27-4-2 and X6MnSiAlNbTi26-3-3 type austenitic steels, after hot deformation as well as after cold rolling, were evaluated in 3.5% NaCl solution using potentiodynamic polarization tests. A type of nonmetallic inclusions and their pitting corrosion behaviour were investigated. Additionally, the effect of cold deformation on the corrosion resistance of high-Mn steels was studied. The SEM micrographs revealed that corrosion damage formed in both investigated steels is characterized by various shapes and an irregular distribution at the metallic matrix, independently on the steel state (thermomechanically treated or cold worked). Corrosion pits are generated both in grain interiors, grain boundaries and along the deformation bands. Moreover, corrosion damage is stronger in cold deformed steels in comparison to the thermomechanically treated specimens. EDS analysis revealed that corrosion pits preferentially nucleated on MnS and AlN inclusions or complex oxysulphides. The morphology of corrosion damage in 3.5% NaCl supports the data registered in potentiodynamic tests.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

Grajcar

Grzegorczyk

Kozłowska

2016

Archives of Metallurgy and Materials

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“…Many researchers have studied the pitting processes, with most of them acknowledging that non-metallic inclusions induced pitting corrosion [9][10][11][12]. Schmuki et al [13] observed the inclusions in high sulfur stainless steel and found that the surroundings of the inclusions were preferentially dissolved and pitting corrosion occurred at the inclusions or their surroundings. Chiba et al observed that the metastable and stable pits were initiated at the MnS/steel boundaries [14].…”

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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“…In the case of commercial steels, it is inevitable that they contain nonmetallic inclusions. Because non-metallic inclusions readily act as pit initiation sites on steels in chloride [7][8][9][10][11][12][13][14][15][16] and decrease their pitting potential, to strike a balance between the mechanical properties and the pitting corrosion resistance, it is necessary to investigate the effect of the tempering time on the pitting corrosion resistance at inclusions. In this work, micro-scale polarization curves for small electrodes including only one MnS inclusion were measured.…”

Section: Journal Of the Electrochemical Societymentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14][15][16] For example, SzklarskaSmialowska 7 and Wranglén 8 reported that sulfide inclusions become the initiation sites for pitting in steels. Avci et al demonstrated that pits are initiated in the immediate surroundings of MnS inclusions in carbon steels.…”

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confidence: 99%

Improving Pitting Corrosion Resistance at Inclusions and Ductility of a Martensitic Medium-Carbon Steel: Effectiveness of Short-Time Tempering

Kadowaki

Muto

Sugawara

et al. 2018

J. Electrochem. Soc.

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The optimal tempering conditions for a martensitic medium-carbon steel (0.47 mass% C) were investigated in terms of balancing ductility and pitting corrosion resistance. By tempering the as-quenched martensite, its Vickers hardness drastically decreased within 0.1 h, suggesting that ductility was sufficiently recovered by short-time tempering. Based on the results of micro-scale polarization in boric-borate buffer solutions with NaCl (pH 8.0), stable pits were initiated at non-metallic inclusions in the specimens tempered for at least 1 h; however, no stable pit was generated on the 0.1 h tempered and as-quenched specimens. Short-time tempering of martensite was suggested to be a feasible approach to striking an optimal balance between facilitating pitting corrosion resistance and achieving the desired mechanical properties of martensitic carbon steels. To reduce the weight of automobiles and other transportation vehicles, ultra-high strength steels with excellent ductility are necessary. It is desirable that excellent mechanical properties be attained without deteriorating the corrosion resistance. Even if organic or inorganic coatings are used in the actual applications of the steels, bare steel surfaces are exposed at cut edges, scratched surfaces, and other damaged areas of the coatings. Therefore, high corrosion resistance remains a fundamental requirement for ultra-high strength steels.A martensitic structure with fine grains is favored for strengthening steels, and interstitial carbon imparts high strength to martensite. The martensitic structure is formed during shear-dominated transformation via quenching.1 In the phase transformation from austenite to martensite in carbon steels, interstitial carbon atoms in the fcc (facecentered cubic) crystal structure of austenite remain as supersaturated carbon in the bct (body-centered tetragonal) martensitic structure. 1-5Supersaturation of interstitial carbon, a fine structure, and a high dislocation density are introduced by this transformation. 5 To optimize the balance between ductility and strength, the as-quenched martensite is subjected to tempering because the ductility of as-quenched martensitic steels is relatively low.1 During this process, the strength of the steel decreases and the ductility recovers, supplying an optimum balance of strength and ductility. In the case of carbon steel, precipitation of carbides also occurs during tempering. As a result, the concentration of interstitial carbon in martensite decreases, which is associated with changes in both the chemical and mechanical properties. Kadowaki et al. demonstrated that the pitting corrosion resistance of as-quenched martensite (0.47 mass% C) is higher than that of low-carbon martensite prepared by quenching after decarburization treatment.6 Despite the optimum balance between strength and ductility achieved by quenching and tempering treatments, the pitting corrosion resistance decreased during tempering. This seems to be because of the decrease of the interstitial carbon concentration. An...

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The composition of the boundary region of MnS inclusions in stainless steel and its relevance in triggering pitting corrosion

Cited by 189 publications

References 25 publications

Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

Pitting Corrosion of Steel Induced by Al2O3 Inclusions

Improving Pitting Corrosion Resistance at Inclusions and Ductility of a Martensitic Medium-Carbon Steel: Effectiveness of Short-Time Tempering

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