scholarly journals Effects of Homoacetogenic Bacteria on the Corrosion Behaviour and Cathodic Protection of AISI 4135 Steel

2020 ◽  
pp. 7545-7558
Author(s):  
Xiangju Liu ◽  
Keyword(s):  
Cathodic Protection ◽  
Corrosion Behaviour ◽  
Homoacetogenic Bacteria

Corrosion Behaviour of Unprotected Weldments in Marine Environments

CORROSION ◽  
10.5006/3824 ◽  
2021 ◽  
Author(s):  
Nicholas Senior ◽  
Lawrence Parkinson ◽  
Magdalene Matchim ◽  
Jennifer Collier ◽  
Hung-Wei Liu
Keyword(s):  
Weld Metal ◽  
Cathodic Protection ◽  
Corrosion Behaviour ◽  
Coast Guard ◽  
Metal Corrosion ◽  
Corrosion Performance ◽  
Accelerated Corrosion ◽  
Potential Safety ◽  
Protection Systems ◽  
Welding Consumables

In the absence of protective measures such as paint or cathodic protection systems, steel weldments, immersed in seawater, are expected to corrode freely. This is particularly true for the ice breakers serving the Canadian Coast Guard, where, in the course of operations, paint is scoured from the vessel hulls and cathodic protection systems were not installed. However, the weldments do not corrode uniformly. In some cases, the weld itself corrodes rapidly and requires regular replacement. At the other extreme, the heat-affected zones corrode instead—a potential safety and integrity concern. The morphology of ice breaker weldment corrosion has altered over the last few decades and this has been attributed to changes in welding consumables and processes. The current study is an investigation into the corrosion characteristics of weldments with a particular focus on the compositional differences between weld metal and hull plate steels. A method has been developed for numerically describing the corrosion of weldment regions (plate steel, heat-affected zones, weld cap passes and weld re-heated zones) arising from an accelerated corrosion test. This in turn enabled the development of an equation that predicts weldment corrosion performance based entirely on material composition. This permits selection of welding consumables that are anticipated to give good corrosion performance, avoiding the extremes of rapid weld metal corrosion and preferential heat-affected zone attack.

scholarly journals Development of carbon anode for cathodic protection of mild steel in chloride environment

2018 ◽  
Vol 65 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Ayomide Osundare ◽  
Daniel Toyin Oloruntoba ◽  
Patricia Popoola
Keyword(s):  
Cast Iron ◽  
Corrosion Rate ◽  
Mild Steel ◽  
Marine Environment ◽  
Cathodic Protection ◽  
Corrosion Behaviour ◽  
Weight Percent ◽  
Content Type ◽  
Sacrificial Anodes ◽  
Grey Cast

Purpose The purpose of this paper is to develop technically efficient and economically effective sacrificial anodes that can be used for cathodic protection (CP) of pipelines in marine environment and fill the knowledge gap in the use of carbon anodes for CP. Design/methodology/approach A sacrificial anode was produced via sand casting by adding varying weight-percent of coal and ferrosilicon to a constant weight-percent of grey cast iron. The hardness of the produced anodes was evaluated using a Rockwell hardness tester. The microstructure of the anodes was observed with scanning electron microscope/energy-dispersive spectroscopy (SEM/EDS). X-ray diffraction (XRD) was used to study the phases present. A potentiostat was used to assess the corrosion behaviour of the produced anodes and mild steel in 3.5 Wt.% NaCl solution. Findings The SEM results showed that some anodes had interdendritic graphite formation, while others had pronounced graphite flakes. The EDS analysis showed carbon and iron to be the prominent elements in the anode. Anodes Bc, B2 and B5 with a corrosion rate of two order of magnitudes were observed to have similar dendritic structures. Anode B4 is the most electronegative with an Ecorr of −670.274 mV Ag/AgCl and a corrosion rate of 0.052475 mmpy. The produced anodes can be used to protect mild steel in the same environment owing to their lower Ecorr values compared to that of mild steel −540.907 mV Ag/AgCl. Originality/value Alloying has been majorly used to improve the efficiency of sacrificial anodes and to alleviate its setbacks. However, development of more technically efficient and economically effective sacrificial anodes via production of composite has not been exhaustively considered. Hence, this research focuses on the development of a carbon based anode by adding natural occurring coal and ferrosilicon to grey cast iron. The corrosion behaviour of the produced anode was evaluated and compared to that of mild steel in marine environment.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

Influence of Carbon on the Hot Corrosion Behaviour of Fe-Base Alloys

1989 ◽  
Vol 30 (9) ◽  
pp. 707-716 ◽  
Author(s):  
A. U. Malik ◽  
M. Ishaq ◽  
Sharif Ahmad ◽  
Sultan Ahmad
Keyword(s):  
Hot Corrosion ◽  
Corrosion Behaviour
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