Untersuchung der Lochfraßkorrosion an chemisch beständigen austenitischen Stählen

Brauns, E.; Schwenk, W.

doi:10.1002/srin.196103233

Cited by 56 publications

(8 citation statements)

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“…Both potential-and current-controlled electrochemical techniques have been utilized to study the pitting mechanism in aluminum alloys (5,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30); however, controversy still exists among researchers as to which electrochemical method accurately assesses the pitting corrosion mechanism. Characteristic potentials determined from these methods are Ep, the breakdown or pitting potential, and E,rot, the protection or repassivation potential.…”

Section: Introductionmentioning

confidence: 99%

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Aylor

Moran

1985

J. Electrochem. Soc.

149

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This paper examines the effect of graphite and silicon carbide reinforcements on the pitting behavior of graphite/aluminum (Gr/Al) and silicon carbide/aluminum (SiC/A1) metal matrix composites. Electrochemical corrosion tests were performed on both Gr/A1 and SiC/A1 composite specimens. Identical tests were completed on powder metallurgy processed aluminum and wrought aluminum of the same composition. The electrochemical behavior of the SiC/A1 composites was essentially identical to that of the powder processed and wrought aluminum alloys; however, the pitting attack on the SiC/Al composites was distributed more uniformly across the surface, and the pits penetrated to significantly less depths. The presence of graphite in the Gr/A1 composites did not cause an electropositive shift in corrosion potential as anticipated, but caused a substantial decrease in resistance to passive film breakdown. This effect is the predominant reason for the poor performance of Gr/At composites in marine environments.Interest in implementation of metal matrix composites (MMC) in marine applications is rapidly expanding due to the materials' higher strength and modulus than that which can be attained by conventional alloying. Utilization of MMC in marine environments requires adequate corrosion resistance. To date, composites considered for marine application are typically aluminum-based, specifically 5000 series or 6061 Al, with reinforcements of graphite (Gr) and silicon carbide (SIC). It has been reported tl~at aluminum alloys suffer localized attack by pitting in chloride environments (1, 2). A reinforcement of Gr or SiC added to the aluminum matrix could potentially decrease the corrosion resistance as compared to an unreinforced alloy due to the structure of the composite. Continuous graphite/aluminum (Gr/A]) composites typically consist of Gr/Al wires (graphite multifilament tows infiltrated with aluminum) diffusion bonded between aluminum foils. This composite configuration could promote wicking of the electrolyte (thereby increasing the corrosion rate) at the foil-to-wire and wire-to-wire interfaces once pitting corrosion progresses through the aluminum foils. The structure of the discontinuous silicon carbide/aluminum (SiC/A1) composites, that of silicon carbide whiskers or particles blended into a powder aluminum matrix could increase the probability of pitting/crevice corrosion at exposed SiC-A1 interfaces in the composite. Dull et al. (3,4) studied the Gr/A1 system in 3.5% NaC1.They concluded that the corrosion rate was slightly higher for Gr/AI relative to 6061 aluminum alloy controls. The explanation for this increased corrosion rate was galvanic corrosion at the graphite fiber-aluminum interface.Trzaskoma et al. (5) studied the SiC/A1 system in 0.1N NaC1. They concluded that the SiC whiskers did not influence the susceptibility of 6061 aluminum to pit initiation, but promoted the development of a smaller size pit morphology relative to 6061 aluminum controls.In this research, both SiC/A1 and Gr/A1 composites were evalua...

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Section: Introductionmentioning

confidence: 99%

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Aylor

Moran

1985

J. Electrochem. Soc.

149

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“…Very little follow up to this work took place, save for the work of Mahla and Neilson (3) in 1947, until the last five or six years during which a considerable amount has appeared in the literature (4)(5)(6)(7)(8)(9).…”

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confidence: 99%

A Contribution to the Applicability of Critical Pitting Potentials

Leckie¹

1970

J. Electrochem. Soc.

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“…This upper limit of the pitting corrosion range should not be confused with the pitting inhibition potential described in ref. [10], as this is based on displacement adsorption of the chloride by nitrate, and therefore exists only in a chloride solution containing nitrate. The existence of this upper limit of the pitting range, previously found in stainless steels 1.4529 (Cronifer 1925 hMo) and 1.4562 (Nicrofer 3127 hMo) and in NiCrMo alloys 2.4856 (Nicrofer 6020 hMo), 2.4819 (Nicrofer 5716 hMoW) and 2.4605 (Nicrofer 5923 hMo) results in a test potential of 0.2V SCE for the CaCl 2 test, attained in a test conducted over 6 h.…”

Section: Development Of the Calcium Chloride Testmentioning

confidence: 99%

Determination of critical pitting temperatures by calcium chloride test, results of round‐robin test

Werner

Rommerskirchen²

2007

Materials & Corrosion

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At the Institute for Corrosion Protection (Institut für Korrosionsschutz) in Dresden, the CaCl2 test was developed to test high‐alloyed CrNiMo steels and NiCrMo alloys and was applied for pitting and crevice corrosion resistance tests of those materials and their weldments. This test was carried out as a potentiostatic test at 0.2VSCE in a solution of 4.5 mol/l CaCl2 with an initial pH value of 3.2. Investigations on the influence of filler material, heat treatment and varying heat inputs per unit length of the welds confirm the applicability of the test. With reference to the results from a round‐robin test carried out by a study group of the GfKORR working committee Corrosion Protection of Iron and Steel (Korrosionsschutz von Eisen und Stahl) on material grade 2.4605 (alloy 59) and its weldments, the study group concludes that, in research projects, the CaCl2 test is a good test to characterise the localised corrosion behaviour of welded joints of high‐alloyed CrNiMo steels and NiCrMo alloys. However, to use it as quality assurance test would be too complex and susceptible to individual measuring differences.

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Untersuchung der Lochfraßkorrosion an chemisch beständigen austenitischen Stählen

Cited by 56 publications

References 0 publications

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

A Contribution to the Applicability of Critical Pitting Potentials

Determination of critical pitting temperatures by calcium chloride test, results of round‐robin test

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