Study Of Corrosion-Friction Behavior Of EH36 In Simulated Polar Marine Working Conditions

Since the 21st century,international competition for marine resources has expanded from coastal areas to the deep sea and polar regions.As global warming intensifies,the rate of Arctic ice melt is accelerating and the "Golden Waterway" of the Arctic Ocean is expected to be fully opened within the next decade.As the sea ice continues to melt,the commercial potential for oil and gas resources and shipping routes in the Arctic is beginning to emerge.As the demand for polar development and applications increases,existing development technologies are no longer adequate.Marine cryogenic steels are widely used in shipbuilding and marine engineering in the Arctic environment,but their friction-corrosion behavior in the polar environment is still relatively little studied.In this paper,the friction-corrosion behavior of EH36 steel under polar marine conditions is investigated with the low-temperature high-strength marine plate steel EH36 as the research object.The initial corrosion behavior of EH36 steel under simulated polar marine conditions and the friction and wear behavior of two friction subsets with EH36 steel substrate and pre-corroded surface at different ambient temperatures are investigated by weightlessness method,scanning electron microscope and energy spectrum analysis,X-ray diffraction analysis,electrochemical test,white light interference morphology observation,friction coefficient measurement and wear volume calculation.The corrosion rate of EH36 steel was found to be 1.65 g·m-2·h-1 for 240 h of corrosion in a simulated polar marine atmosphere,and 1.75 g·m-2·h-1 with the addition of UV light.UV light facilitated the corrosion process of EH36 steel.The main corrosion products produced in this environment were β-FeOOH and Fe3O4.small amounts of γ-FeOOH and protective α-FeOOH began to appear after 240 h.The corrosion kinetics followed the empirical equation D=Atn,with corrosion still in an accelerated phase after 240 h.The corrosion weight loss of EH36 steel·under a mixture of NaCl and NaHSO3 corrosive media was greater than that under a single media.In this experimental environment,the effect of NaCl and NaHSO3 mixture on corrosion weight loss is:1:1>3:1>5:1>NaCl alone>NaHSO3 alone.the main components of the rust layer after corrosion with NaHSO3 and NaCl mixture are Fe3O4 with γ-FeOOH and α-FeOOH.the presence of SO2 makes the corrosion process easy to produce α-FeOOH.The content of α-FeOOH in NaHSO3 media increased with the corrosion time.After 240 h of corrosion,a mixture of NaCl and NaHSO3 had a greater effect on the corrosion pit depth of EH36 steel than NaHSO3 alone.the presence of Cl-caused the corrosion pits to be characterized by localized corrosion,whereas SO2 caused a uniform corrosion pattern on the sample surface.The friction and wear experiments were conducted using a ball-disk reciprocating wear test.Two friction subsets consisting of EH36 steel samples and two pre-corroded steel samples with Si3N4 ceramic balls and diamond grinding heads,respectively,were used.The experimental results showed that the average friction coefficient of the EH36 steel sample under the ceramic ball grinding head was the largest,and the average friction coefficient of both pre-corroded samples was smaller than that of the EH36 steel sample.The friction coefficient curve of EH36 steel sample with ceramic ball grinding head has a process of rising from the initial state to the stable value,and the time required to reach the stable value increases as the temperature of the experimental environment decreases.The friction curves of the three samples with diamond friction subsets were highly overlapping,and the average friction coefficient was stable.The depth of the abrasion marks of the diamond grinding head is much larger than that of the ceramic ball,and the shape of the abrasion marks is "bamboo knot".The wear mechanism of Si3N4 ceramic balls at room temperature is mainly adhesive wear and surface fatigue wear,while abrasive wear and plastic deformation also exist.In low temperature environment,the ceramic ball friction sub will be affected by the low temperature brittleness,the abrasive chips are "turtle back" fragment change,the wear mechanism for the abrasive wear and oxidation wear together.Diamond friction with the ambient temperature decreases the surface abrasive chips appear loose "curl"phenomenon.The results of this study are of great theoretical and practical significance for solving the corrosion-friction problems of marine engineering steels in polar marine condition.Meanwhile,it provides a useful reference for further in-depth study of corrosion-friction problems of marine engineering materials in polar marine condition.