Marine environment behaves as electrolyte, thus having impact on shipbuilding metals causing corrosion and fouling which increases the ships resistance in navigation. Effects of corrosion cause damage of a steel which can reduce its ability of safety working load, leading to breakdown whereby endangering ships safety at sea. Corrosion is a chemical process of material wear and tear; chemical reaction takes place between metal and environment where the product of the reaction is rust. In this research effort was made to determine the effects of marine environment on the shipbuilding steel AH36 characteristics. Specimens of the steel were welded with MIG (Metal Inert Gas) and MMA (Manual Metal Arc) welding techniques and were exposed to marine environment for a period of three months. In addition, different tests are done to determine changes that have occurred in weld and material due to exposure to marine environment. One mode of determining changes is done by measuring the weight residuals of specimens, other tests used in research are: radiographic and penetrant testing to determine weld quality and micro analysis of material structure. Results from the tests are compared to the results of identical specimens exposed to fresh water and air. Results of each specimen are compared before and after being exposed to different environment, besides that into account was taken quality of weld made by amateur and professional welders. Research shows quality deterioration of shipbuilding steels in case when the material is not covered with protection layer of paint or any other protection against corrosion and at the end it gives a comparison between different environment factors which have influence on corrosion of metal.