Study On Welding Structure Stress Corrosion Fatigue Properties Of2205Duplex Stainless Steel

It is a complex trade activity of ocean transportation of liquid chemicals. It isnecessary to ensure the safety and have certain economic benefits in the transportprocess, so it is particularly important for the manufacturing of the liquid chemical ships.There are two important links in the manufacturing process of chemical ships, the firstis the material selection of manufacturing ships, and the second is a large number ofwelding processes used in manufacturing process. The stainless steel is more and moreselected to manufacture the liquid chemicals ships after efforts of several generations.This is because that there is a layer of natural passivation film on the surface of thestainless steel, which can protect stainless steel from corrosion. However, engineeringapplications confirmed that the passivation layer can be partial destroyed by a halogenion (such as chloride ion) and the generation of new protective film is impeded, so thestructure is cracked by the corrosion. The stress corrosion cracking of the generalstainless steel is solved in halogen ion environment by the birth of the duplex stainlesssteel, and the2205duplex stainless steel (DSS) is the most representative. Theautogenous passivation layer and the proportion organization of each phase in thematerial will be destroyed by welding process, and the material of corrosion resistancecan be reduced, so it is significant to study the corrosion resistance of the weldedstructure.The smelting technology of duplex stainless steel is mastered in some westerndeveloped countries; the ordinary duplex stainless steel can be only produced in china.Pay attention to the marine resources in recent years, the strong demand of the duplexstainless steel lead to the research of smelting technology is more active in the majorsteel factory. The smelting technology of some super duplex stainless steel have be gotin some large steel factory, at the same time, domestic steel products is in favor used inengineering due to the prices advantages of domestic steel. The2205DSS produced byTAIYUAN IRON&STEEL(GROUP) CO., LTD is the first time used to manufacturethe cabin of the chemical ship by state-owned enterprises East Sichuan ShipManufactured CO., LTD in2007in china. Because it is the first time that this material isextensive use in the domestic ocean vessels, the lack of experience in reality, part of the chemical ship has obvious corrosion damage after6years service.In this paper, the study objects are the2205DSS used by East Sichuan ShipManufactured CO., LTD to manufacture chemical ship and its welded structure. Thecorrosion resistance of duplex stainless steel welded structure in a variety ofenvironments is discussed. The corrosion rate of the welded structure in acid and alkali,and stress corrosion in simulated seawater (3.5%sodium chloride solution) fatigue arealso researched by experiment and they are processed by use of numerical analysis ofexperimental data. Then the Zeiss LEO1530VP scanning electron microscope is usedmicroscopic analysis the surface of the corrosion and stress corrosion fatigue fracture.The2205duplex stainless steel welded structure in the life of the project is applicationforecasts by miner theory. All of Experimental conclusion of the study will provide atheoretical basis for the safety monitoring of chemicals ship which is manufactured by2205DSS.