Analysis of prolonged marine exposure on properties of AH36 steel

Corrosive marine environment has negative impact on welded steel structures, so it is necessary to investigate the effect of sea exposure on such materials. This research investigates the change of mechanical properties and surface condition of AH36 shipbuilding steel butt-welded specimens exposed to natural marine environment for prolonged periods (6, 12 and 24 months). Contrary to accelerated tests in simulated laboratory environment, this approach is rarely used. Engineering stress-strain diagrams are obtained using standardized procedures for uniaxial tensile tests, giving insight into the change of material strength due to length of exposure and type of corrosive environment (water, sea water, sea waves). Using impact tests, values of measured Charpy impact energy are given. Additionally, relative mass change over time is given along with calculated corrosion rates. Corroded surface is microscopically inspected and comparison, based on number and dimensions of corrosion pits in the observed area, is given.