High Temperature Erosion Characteristics Of GH4738 Superalloy In Marine Atmospheric Environment

Due to having excellent high-temperature resistance,Nickel-based superalloys have been the primary material for manufacturing hot-end parts of aerospace engines.However,corrosion-oxidation-wear is the main cause of damage and failure of hot-end components of aero-engines in the marine atmosphere,causing large numbers of direct economic losses and requiring higher performance aero-engine materials.Therefore,it is vital to determine the damage and failure mechanism and characteristics of the hot-end component materials under actual service conditions of the aircraft.In this paper,the experiments based on the multi-factor cyclic interaction of hightemperature oxidation-high-temperature erosion-marine chemical corrosion were conducted on the target material of superalloy GH4738.The detailed examination of OM,scanning electron microscope,X-ray diffractometer,and XPS surface analysis,hardness testing,residual stress testing,and TEM testing technologies also are performed subsequently.The influencing rules of different marine atmospheric corrosion environments and different actual service conditions on the corrosion and wear of key components of aeroengines and its microscaled corrosion and wear mechanisms and characteristics are systematically studied.The main contents are as follows:(1)Through three-factor alternating cycle tests based on marine chemical corrosionhigh temperature oxidation-high temperature erosion and two-factor alternating cycle tests based on high-temperature oxidation-high temperature erosion,the influence of the threefactor and the two-factor on the damage of GH4738 alloy was studied.Erosion rates in the three-factor alternating cycle tests,two-factor alternating cycle tests,and the original tests are analyzed.The results show that the three-factor and the two-factor erosion rates gradually decrease with the cycle,and the decreasing range is 1.2%-30%,12.6%-19.7%,respectively.The decrease in erosion rate is due to the increase in subsurface layer hardness.In addition,the presence of residual stress and the combination of the hardened layer together improve the anti-erosion performance.The reduced density of the oxide layer,the thinner thickness of the hardened layer,and the reduction of residual stress are why the erosion rate of the three factors is higher than the erosion rate of the two factors.It shows that in the cyclic test,corrosion promotes the erosion damage of the material.(2)The phase cycle tests,i.e.,conducting a high-temperature erosion test after specific cycles of marine chemical corrosion-high temperature oxidation tests,were studied.And the erosion rates of the phase cycle tests were compared with the three-factor alternating cycle tests.The results show that the thickness of the oxide layers in the phase cycle tests is 2.92?m,7.33 ?m,and 9.32 ?m,respectively.The increase in the thickness of the oxide layer can resist some of the impact energy to decrease the erosion rate of the material.The aggravation of grain boundary corrosion reduces the bonding force between the material grains,making the material is easier to remove and increasing the erosion rate of the material.The erosion rate is dominated by the thin and loose oxide layer in the first four cycles of the three-factor alternating cycle,allowing the erosion rate is higher than that of the two-factor phase cycle.A hardened layer is formed in the three-factor tests' final two cycles,which lower the erosion rate than in the phase cycle tests.It is of great practical significance to study the alternate damage mechanism of marine atmospheric corrosion,high-temperature oxidation and high-temperature erosion in the process of space shuttle's marine atmospheric environment parking and mission execution to prevent the hot end components from being damaged.