Search

Carbon steels are widely used in the process of oil production and therefore exposed to the constant action of the electrolytes, rich in dissolved gases, salts and organic acids. This results in significant corrosion failure, high costs and a negative environmental impact. The most common method of corrosion protection is the use of corrosion inhibitors, which is limited by economic and environmental requirements. The aim of this work was to investigate the effect of olive leaf extract as non-toxic, cost-effective corrosion inhibitor and the possibility of its application in the protection of J55 carbon steel used in tubing manufacturing in the oil industry. Electrochemical tests were performed after the steel was exposed to simulated realistic conditions. These conditions were as follows: chloride-carbonate solution saturated with CO2, stirred using a magnetic stirrer at 300 r min-1 speed at 35 °C temperature. The concentrations of 50 to 300 mg L-1 extract were added. Linear polarization in Eoc ± 250 mV potential field and the Tafel extrapolation method in the presence of the extract determined that the extract acts as a mixed type corrosion inhibitor with the predominant influence on the anodic process. Linear polarization resistance monitoring over a period of 24 hours has proven that the extract provides high protection from corrosion. Recorded electrochemical impedance spectra in the presence of the extract show the existence of the second time constant in the field of high frequency, indicating the presence of the inhibitor film on the surface of tested steels. This is further confirmed by the recording in FTIR spectra. All testing methods prove the extract’s high inhibitor efficiency against corrosion of J55 carbon steel in tested conditions.

This paper reports the structural and electrochemical behaviour of (Ti(C, N)) and titanium diboride (TiB2) coatings prepared by PA CVD- Plasma Asisted Chemical Vapour Depositon process. Ttitanium carbonitride and titanium diboride are widely used as reinforcing materials in applications demanding high corrosion and wear resistance. The microstructure of both layers consists of primary titanium particles surrounded by a eutectic matrix, containing ferrite, eutectic boride, and titanium carbonitrides. The electrochemical characterisation was performed using electrochemical methods for analysing corrosion surface ; surface morphology was characterised by using a high-resolution scanning electron microscope (SEM). The results showed a susceptible to pitting corrosion and increased corrosion rate in 3.5% NaCl solution.

Shopprimers provide a temporary protection to the mild steel metal construction exposed to corrosion of the environment during the phase of assembly. Unprotected parts of construction within this time period can corrode and produce a rising cost of surface preparation and building of the entire structure. In this paper different types of shopprimers are described with special attention given to their anti-corrosive properties during exploitation. Solvent and water based epoxy shopprimers as well as zinc-silicate shopprimer were tested for their corrosion resistance and influence on the weld quality. Welding over shopprimer can cause defects in a welding joint and lead to unpredicted additional production costs. In order to define the influence of the thickness and the type of shopprimer on the weld quality and corrosion resistance, specimens were submitted to radiographic and metallographic testing as well as accelerated corrosion study. The samples were prepared by Flux-Cored Arc Welding (FCAW).

In dieser Arbeit werden die Wasserstoffversprödungsneigung hochfester Stähle und die Wirkung von Mikrolegierungselementen auf die Versprödungsneigung und auf die Wasserstoffdiffusion untersucht. Korrelationen zwischen den Ergebnissen aus mechanischen Versuchen und Wasserstoffdiffusionsmessungen liefern Erklärungen für die unterschiedliche Versprödungsanfälligkeit von Stählen. Mikrolegieren verändert das Versprödungsverhalten von Stählen sowie die Ausbildung von Wasserstofffallen in den Gefügen. In this work the hydrogen embrittlement (HE) susceptibility of high strength steel grades is investigated as well as the impact of microalloying elements on hydrogen diffusion and HE-susceptibility. Correlating results of various mechanical tests and hydrogen diffusion measurements provide explanations for the varying HE-susceptibility of the grades. Microalloying seems to influence the HE-sensitivity of these grades as well as the formation of hydrogen traps in the microstructures.