Abstract: In the present study, two TRIP-assisted steels were designated as A (having no Cr and Cu content) and B (having higher Ni, Cr and Cu content) heat treated under different conditions, and the correlation between its heat treatment, microstructure and properties were investigated. Micro structural examination was carried out by optical microscope and scanning electron microscope after electrolytic etching. Non-destructive electrochemical and ultrasonic testing on two TRIP-assisted steels was used to find out corrosion and mechanical properties of different alter microstructure phase’s steels. Furthermore, micro structural studies accompanied by the evaluation of mechanical properties revealed that steels having martensite phases with higher corrosive and hardness value were less sound velocity and also steel’s microstructure having finer grains that was more grain boundary was less corrosion resistance. Steel containing more Cu, Ni and Cr was less corrosive compared to other steels having same processing or microstructure.
Abstract: In situ observation of absorption spectral change of
heptil viologen cation radical (HV+.) was performed by slab optical
waveguide (SOWG) spectroscopy utilizing indium-tin-oxide (ITO)
electrodes. Synchronizing with electrochemical techniques, we
observed the adsorption process of HV+.on the ITO electrode. In this
study, we carried out the ITO-SOWG observations using KBr aqueous
solution containing different concentration of HV to investigate the
concentration dependent spectral change. A few specific absorption
bands, which indicated HV+.existed as both monomer and dimer on
ITO electrode surface with a monolayer or a few layers deposition,
were observed in UV-visible region. The change in the peak position
of the absorption spectra from adsorption species of HV+. were
correlated with the concentration of HV as well as the electrode
potential.
Abstract: The aim of this paper is to compare the effectiveness and electrochemical behavior of typical oilfield corrosion inhibitors with previous oilfield corrosion inhibitors under the same electrochemical techniques to control preferential weld corrosion of X65 pipeline steel in artificial seawater saturated with carbon dioxide at a pressure of one bar. A secondary aim is to investigate the conditions under which current reversal takes place. A flow channel apparatus was used in the laboratory to simulate the actual condition that occurs in marine pipelines. Different samples from the parent metal, the weld metal and the heat affected zone in the pipeline steel were galvanically coupled. The galvanic currents flowing between the weld regions were recorded using zero-resistance ammeters and tested under static and flowing conditions in both inhibited and uninhibited media. The results show that a current reversal took place when 30ppm of both green oilfield inhibitors were present, resulting in accelerated weld corrosion.