Abstract
Some marine and offshore structure elements exploited in the water cannot be brought to the surface of the water as this will generate high costs, and for this reason, they require in-situ repairs. One of the repair techniques used in underwater pad welding conditions is a wet welding method. This paper presents an investigation of the abrasive wear resistance of coatings made in wet welding conditions with the use of two grades of covered electrodes—an electrode for underwater welding and a commercial general use electrode. Both electrodes were also used for manufacturing coatings in the air, which has been also tested. The Vickers HV10 hardness measurements are performed to demonstrate the correlation in abrasive wear resistance and the hardness of each specimen. The microscopic testing was performed. For both filler materials, the coatings prepared in a water environment are characterized by higher resistance to metal–mineral abrasion than coatings prepared in an air environment—0.61 vs. 0.44 for commercial usage electrode and 0.67 vs. 0.60 for underwater welding. We also proved that in the water, the abrasive wear was greater for specimens welded by the general use electrode, which results in a higher hardness of the layer surface. In the air welding conditions, the layer welded by the electrode for use in the water was characterized by a lower hardness and higher resistance to metal–mineral abrasion. The microstructure of the prepared layers is different for both the environment and both electrodes, which results in abrasive wear resistance.
Highlights
The number of offshore structures that are operated in changing and harsh conditions increases each year [1]
The second disadvantage associated with welding underwater is the high susceptibility of steel to form brittle structures in the heat-affected zone (HAZ), which causes high values of residual stress [35]
These factors, including a high cooling rate, are responsible for the cold cracking of high-strength low-alloy steel (HSLA) joints made in underwater conditions [35,36]
Summary
The number of offshore structures that are operated in changing and harsh conditions increases each year [1]. Apart from typical damage in the form of cracks, these phenomena can cause a reduction in the cross-section of the elements These factors make it necessary to use protective coatings on the steel surfaces, which improve the corrosion and wear resistance [6,7]. The second disadvantage associated with welding underwater is the high susceptibility of steel to form brittle structures in the heat-affected zone (HAZ), which causes high values of residual stress [35] These factors, including a high cooling rate, are responsible for the cold cracking of high-strength low-alloy steel (HSLA) joints made in underwater conditions [35,36]. As the results of wear tests of the underwater welded joints properties are extremely rarely reported, in this study, underwater manual metal arc coating deposition on HSLA S355G10+N steel was carried out. To the best of the author’s knowledge, in the literature, there are no researches published that provide a detailed discussion on the problem of abrasive wear resistance of coatings manufactured in the water environment
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