Why is weld corrosion defined as the phenomenon of corrosive degradation of the weld metal?
Thread Content
The vast majority of welded structures are made by welding rolled steel, or aluminum and titanium. The welds have a cast-like structure, and there is also macroscopic and microscopic segregation (the uneven distribution of various elements in an alloy during crystallization is known as segregation). During the primary crystallization of the welding pool, due to the rapid cooling rate, the chemical composition in the already solidified weld metal does not have enough time to diffuse, resulting in uneven distribution and segregation). In many application environments, especially harsh corrosive conditions such as those in the marine and chemical industries, the welds may have lower resistance to uniform corrosion than the base material, leading to premature corrosion; in addition, segregation can also cause localized corruptions such as pitting in the weld metal.
Weld corrosion occurs because, during the welding process, the weld metal undergoes rapid cooling and crystallization, resulting in uneven composition; this makes it prone to corrosion in harsh environments before the base material. Especially in marine or chemical environments, this segregation phenomenon can lead to localized corrosion at the weld area, such as pitting. .
Weld rust removal may not be done properly, and paint spraying is inadequate.