Corrosion properties of stainless steel in the marine environment

Morska je voda vjerojatno najrasprostranjeniji kemijski spoj na svijetu, ali je istovremeno i s korozijskog stajališta ona može biti vrlo agresivna. Zbog toga je primjena metala u morskim uvjetima vrlo zahtjevna. Nehrđajući čelik pokazao se kao najbolji materijal u morskoj atmosferi. Ima sjajna mehanička svojstva i vrlo dobru otpornost na koroziju. Mnogo je područja primjene nehrđajućeg čelika u uvjetima morske atmosfere, posebice u naftnoj i plinskoj industriji te brodogradnji, gdje je metal najčešće izložen slanoj morskoj vodi ili drugim korozivnim medijima. Iako je nehrđajući čelik idealan materijal za primjenu u morskoj vodi, ipak ima određenih ograničenja. Otpornost na koroziju ovisi o legirnim elementima, temperaturi, brzini protoka vode, otopljenom kisiku, udjelu klorida i morskim organizmima. Ovaj rad opisuje svojstva i postojanost nehrđajućeg čelika u morskom okolišu i kako se njegova upotreba može poboljšati. U eksperimentalnom dijelu rada provedena su elektrokemijske korozijska ispitivanja različitih vrsta nehrđajućih čelika u kloridnom mediju te su analizirani rezultati i izvedeni zaključci.Seawater is probably the most widely available chemical compound in the world, but most people are not aware that it can be very aggressive from the corrosion point of view. Because of that, marine applications are very demanding. Stainless steel has proven to be the best material in marine environment. It has great mechanical properties, and is really resistant to corrosion. There are many applications of stainless steel, especially within the oil and gas industry and shipbuilding, in which metal is most often exposed to saltwater or other corrosive environments. Although, stainless steel is the ideal material for marine applications, it still has some limitations. It`s corrosion resistance depends on alloyed materials, temperature, flow rate, dissolved oxygen, chlorine content and marine organisms. This thesis describes the performance of stainless steel in marine environment and how the performance can be improved. In the experimental part of the thesis electrochemical tests were carried out with various types of stainless steel in chloride medium and the results from these test were analyzed and some conclusions have been reached