Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (21) (entfernen)
Schlagworte
- Corrosion (7)
- Atmospheric corrosion (4)
- Stainless steel (4)
- Korrosion (3)
- Chromate (2)
- Concrete (2)
- Corrosion protection (2)
- Electrochemical tests (2)
- Grease (2)
- Hydrogen evolution (2)
- Hydrogen-induced stress corrosion cracking (2)
- Prestressed systems (2)
- Prestressing steel (2)
- Reinforcement (2)
- Reinforcing steel (2)
- Wax (2)
- Aluminium (1)
- Betonstahl (1)
- Cathodic protection (1)
- Cement (1)
- Chlorid-induced corrosion (1)
- Chloride (1)
- Civil engineering (1)
- Concrete parameters (1)
- Corrosion resistance (1)
- Corrosion testing (1)
- Dauerhaftigkeit (1)
- Duplex stainless steels (1)
- EPR test (1)
- Electrochemical measurements (1)
- Exposure tests (1)
- Failure (1)
- Free weathering (1)
- Galvanic corrosion (1)
- Galvanized construction elements (1)
- Galvanized elements (1)
- Galvanized rebar (1)
- Galvanized steel (1)
- Grinding (1)
- Indoor swimming pools (1)
- Intercrystalline corrosion (1)
- KorroPad (1)
- Marine atmosphere (1)
- Maritime Atmosphäre (1)
- Maritime atmosphere (1)
- Monitoring (1)
- Nichtrostender Stahl (1)
- Passive layer (1)
- Pitting corrosion (1)
- Polarization (1)
- Potential mapping (1)
- Potentialfeldmessung (1)
- Prestressed concrete (1)
- Pull-out tests (1)
- Rebar (1)
- Salinization (1)
- Self-corrosion (1)
- Sprayed zinc layer (1)
- Stainless steels (1)
- Steel reinforcement (1)
- Surface finish (1)
- Surface protection system (1)
- Versalzung (1)
- Verzinkt (1)
- Werkstoffauswahl (1)
- X-ray tomography (1)
- Zinc (1)
Organisationseinheit der BAM
Systematic laboratory and field exposure tests allow to compare nine different stainless steels (three ferritic, three austenitic, and three duplex grades) for civil engineering applications. The influence of surface finish was also taken into account by choosing five different industry-specific features. The three duplex stainless steels revealed excellent corrosion resistance under most of the test conditions. Especially for applications in civil engineering the lean duplex steels offer distinct advantages. The manganese-alloyed 1.4376 and the ferritic steel 1.4509 cannot be recommended as alternative materials as they did not perform satisfactorily.
Due to the large number of stainless steels with different chemical composition and different microstructure the selection of the suitable material represents a huge challenge. In order to facilitate the appropriate grade selection, in the current European standard EN 1993-1-4 a procedure is defined based on the use of a look-up table considering the key variables that influence the selection of stainless steels. The table uses descriptions that competent designers should be able to readily understand or define without prior knowledge. The output from the look-up table is used to select alloys based on a Corrosion Resistance Class (CRC) from I to V. The advantage of this approach is that the designer simply specifies the relevant CRC and does not need to consider in detail which of the many (very similar) alloys to specify.
Risk of stress corrosion cracking of prestressing steels in contact with galvanized components
(2010)
Nine different stainless steel alloys were exposed for 5 years under marine environment and their corrosion behaviour was compared and assessed. The investigation of four different surface finishes for all alloys tested further enabled to consider industry-specific features of the surface finish for the material comparison. The results of the exposure tests yield conclusions regarding the influence of alloy composition, surface finish and exposure duration under marine environment. The three duplex stainless steels revealed excellent corrosion resistance even in case of crevices during the 5 years of exposure under the given exposure conditions. Also the molybdenum-alloyed ferritic steel 1.4521 showed good corrosion resistance comparable to the classical austenitic materials 1.4301 and 1.4404.
The presented investigations have proved the principal suitability of the KorroPad method to assess the passive layer stability of stainless steels. The electrochemical mode of action could be described in detail and limitations of the applicability have been demonstrated. The influence of different surface finishes has been investigated and verified by known methods for describing corrosion resistances. As a result, the increased corrosion susceptibility of two ground surfaces has been detected, but also the corrosion resistance of further surface finishes could be confirmed.
About the long-term protection behaviour of corrosion protection materials (filling materials) for prestressed systems under critical environmental conditions is only little known. The corrosion protection effect is usually based on theoretical considerations and is proven by short-term tests. The selection of the different products is mainly made according to economical or workability criteria. In a research project the barrier effect of different commercial corrosion protection materials (waxes as well as oil-based greases) against water, their tendency for undercutting as well as their additional corrosion protection effect were investigated. The exposure tests were carried out with non-stressed as well as stressed prestressing steel specimens which were subjected to critical conditions (condensed water, artificial soil solution, direct soil contact). Parallel to these long-term exposure tests the applicability of different electrochemical techniques and their significance with respect to testing the corrosion protection ability and water absorption was evaluated. Within the project a suitable method for simple testing the performance of corrosion protection materials under real conditions was developed. By means of a small compact cell submicroscopical reactions of the used sensors could be measured. The high sensitivity of this measuring technique enables the detection of degradation processes at thin protection layers.
Investigations of corrosion on small cathodes in reinforced concrete - observations and suggestions
(2009)
Corrosion of steel reinforcement in concrete exposed to chloride containing environments is a serious
problem in civil engineering practice. The standards and guidelines contain only minimum
requirements regarding concrete quality and concrete cover. In very critical cases, for example the
ingress of chlorides, the application of different coatings is currently the only possibility to protect the
reinforced concrete structures. In this case the modelling of reinforcement corrosion would be more
practical. One sub-project of a DFG-research project (FOR 537) is currently performed at the Federal
Institute for Materials Research and Testing (BAM). Aim of the sub-project is the description of
corrosion propagation and the characterization of the corrosion on specimens with small cathodes by
electrochemical parameters. The electrochemical parameters are determined by suitable
electrochemical measurements, considering concrete parameters as well as different environmental
conditions.
The salinization and contamination of metal surfaces by chloride-containing aerosols is of great importance with regard to corrosion phenomena of damaged coated metal surfaces and stainless steels in the maritime sector and in offshore applications. Detailed questions have to be answered to clarify whether and to what extent salinization of the surface has an influence on the adhesion and durability of coatings in repairing applications and on pitting occurrence on stainless steels under atmospheric conditions. The questions arise which degree of salinization is reached after which period of time and how a defined and reproducible salinization can be simulated in the laboratory for further systematic investigations. The article is dedicated to these questions. Results of a field trial on the Island of Heligoland are presented and a simple procedure for a defined loading of metal surfaces with chlorides at a laboratory scale using a design of experiments (DoE) approach is introduced.
The corrosion resistance of aluminium surfaces is closely linked to the surfacecstate after a grinding process. For years, iron‐containing abrasive materials were suspected to lead to increased corrosion susceptibility after processing of aluminium surfaces. To prove a possible correlation between the iron content of an abrasive and the corrosion behaviour of aluminium components, scientific investigations and experimentally practical corrosion tests are necessary.
For the current investigation, specimens of a technical Al‐Si alloy from the same batch were used. The test specimens were mechanically ground with various resin‐bonded model abrasives containing different iron contents. The performed corrosion tests did not reveal a negative influence of the different iron‐containing abrasives on the corrosion behaviour of the Al–Si alloy.
However, the most sensitive measuring method (electrochemical noise)
showed differences in the surface activity depending on the type of abrasive.